dual-phase, +0.6v to +3.3v output parallelable, average

32
General Description The MAX5065/MAX5067 dual-phase, PWM controllers provide high-output-current capability in a compact package with a minimum number of external compo- nents. The MAX5065/MAX5067 utilize a dual-phase, average-current-mode control that enables optimal use of low R DS(ON) MOSFETs, eliminating the need for exter- nal heatsinks even when delivering high output currents. Differential sensing enables accurate control of the out- put voltage, while adaptive voltage positioning provides optimum transient response. An internal regulator enables operation with input voltage ranges of +4.75V to +5.5V or +8V to +28V. The high switching frequency, up to 500kHz per phase, and dual-phase operation allow the use of low-output inductor values and input capacitor values. This accommodates the use of PC board- embedded planar magnetics achieving superior reliabili- ty, current sharing, thermal management, compact size, and low system cost. The MAX5065/MAX5067 also feature a clock input (CLKIN) for synchronization to an external clock, and a clock output (CLKOUT) with programmable phase delay (relative to CLKIN) for paralleling multiple phases. The MAX5065/MAX5067 also limit the reverse current if the bus voltage becomes higher than the regulated output voltage. These devices are specifically designed to limit current sinking when multiple power-supply modules are paralleled. The MAX5065 offers an adjustable +0.6V to +3.3V output voltage. The MAX5067 output voltage is adjustable from +0.8V to +3.3V and features an overvolt- age protection and a power-good output signal. The MAX5065/MAX5067 operate over the extended temperature range (-40°C to +85°C). The MAX5065 is available in a 28-pin SSOP package. The MAX5067 is available in a 44-pin thin QFN package. Refer to the MAX5037A data sheet for a VRM 9.0/VRM 9.1-compati- ble, VID-controlled output voltage controller in a 44-pin QFN package. Applications Servers and Workstations Point-of-Load High-Current/High-Density Telecom DC-DC Regulators Networking Systems Large-Memory Arrays RAID Systems High-End Desktop Computers Features +4.75V to +5.5V or +8V to +28V Input Voltage Range Adjustable V OUT +0.6V to +3.3V (MAX5065) +0.8V to +3.3V (MAX5067) Up to 60A Output Current Internal Voltage Regulator for a +12V or +24V Power Bus Programmable Adaptive Output Voltage Positioning True Differential Remote Output Sensing Out-of-Phase Controllers Reduce Input Capacitance Requirement and Distribute Power Dissipation Average-Current-Mode Control Superior Current Sharing Between Individual Phases and Paralleled Modules Accurate Current Limit Eliminates MOSFET and Inductor Derating Limits Reverse-Current Sinking in Paralleled Modules Integrated 4A Gate Drivers Selectable Fixed Frequency 250kHz or 500kHz Per Phase (Up to 1MHz for Two Phases) External Frequency Synchronization from 125kHz to 600kHz Internal PLL with Clock Output for Paralleling Multiple DC-DC Converters Thermal Protection 28-Pin SSOP Package (MAX5065) 44-Pin Thin QFN Package (MAX5067) MAX5065/MAX5067 Dual-Phase, +0.6V to +3.3V Output Parallelable, Average-Current-Mode Controllers ________________________________________________________________Maxim Integrated Products 1 19-3035; Rev 1; 11/03 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. Ordering Information PART TEMP RANGE PIN-PACKAGE MAX5065EAI -40°C to +85°C 28 SSOP MAX5067ETH -40°C to +85°C 44 Thin QFN Selector Guide and Pin Configurations appear at end of data sheet.

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General DescriptionThe MAX5065/MAX5067 dual-phase, PWM controllersprovide high-output-current capability in a compactpackage with a minimum number of external compo-nents. The MAX5065/MAX5067 utilize a dual-phase,average-current-mode control that enables optimal useof low RDS(ON) MOSFETs, eliminating the need for exter-nal heatsinks even when delivering high output currents.

Differential sensing enables accurate control of the out-put voltage, while adaptive voltage positioning providesoptimum transient response. An internal regulatorenables operation with input voltage ranges of +4.75V to+5.5V or +8V to +28V. The high switching frequency, upto 500kHz per phase, and dual-phase operation allowthe use of low-output inductor values and input capacitorvalues. This accommodates the use of PC board-embedded planar magnetics achieving superior reliabili-ty, current sharing, thermal management, compact size,and low system cost.

The MAX5065/MAX5067 also feature a clock input(CLKIN) for synchronization to an external clock, and aclock output (CLKOUT) with programmable phase delay(relative to CLKIN) for paralleling multiple phases. TheMAX5065/MAX5067 also limit the reverse current if thebus voltage becomes higher than the regulated outputvoltage. These devices are specifically designed to limitcurrent sinking when multiple power-supply modules areparalleled. The MAX5065 offers an adjustable +0.6V to+3.3V output voltage. The MAX5067 output voltage isadjustable from +0.8V to +3.3V and features an overvolt-age protection and a power-good output signal.

The MAX5065/MAX5067 operate over the extendedtemperature range (-40°C to +85°C). The MAX5065 isavailable in a 28-pin SSOP package. The MAX5067 isavailable in a 44-pin thin QFN package. Refer to theMAX5037A data sheet for a VRM 9.0/VRM 9.1-compati-ble, VID-controlled output voltage controller in a 44-pinQFN package.

ApplicationsServers and Workstations

Point-of-Load High-Current/High-DensityTelecom DC-DC Regulators

Networking Systems

Large-Memory Arrays

RAID Systems

High-End Desktop Computers

Features +4.75V to +5.5V or +8V to +28V Input Voltage

Range

Adjustable VOUT+0.6V to +3.3V (MAX5065)+0.8V to +3.3V (MAX5067)

Up to 60A Output Current

Internal Voltage Regulator for a +12V or +24VPower Bus

Programmable Adaptive Output VoltagePositioning

True Differential Remote Output Sensing

Out-of-Phase Controllers Reduce InputCapacitance Requirement and Distribute PowerDissipation

Average-Current-Mode ControlSuperior Current Sharing Between IndividualPhases and Paralleled Modules

Accurate Current Limit Eliminates MOSFET andInductor Derating

Limits Reverse-Current Sinking in ParalleledModules

Integrated 4A Gate Drivers Selectable Fixed Frequency 250kHz or 500kHz Per

Phase (Up to 1MHz for Two Phases)

External Frequency Synchronization from 125kHzto 600kHz

Internal PLL with Clock Output for ParallelingMultiple DC-DC Converters

Thermal Protection

28-Pin SSOP Package (MAX5065)

44-Pin Thin QFN Package (MAX5067)

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________________________________________________________________Maxim Integrated Products 1

19-3035; Rev 1; 11/03

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Ordering InformationPART TEMP RANGE PIN-PACKAGE

MAX5065EAI -40°C to +85°C 28 SSOP

MAX5067ETH -40°C to +85°C 44 Thin QFN

Selector Guide and Pin Configurations appear at end ofdata sheet.

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2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS(VCC = +5V, circuit of Figure 1, TA = -40°C to +85°C, unless otherwise noted. Typical specifications are at TA = +25°C.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functionaloperation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure toabsolute maximum rating conditions for extended periods may affect device reliability.

IN to SGND.............................................................-0.3V to +30VBST_ to SGND........................................................-0.3V to +35VDH_ to LX_ .................................-0.3V to [(VBST_ - VLX_) + 0.3V]DL_ to PGND..............................................-0.3V to (VCC + 0.3V)BST_ to LX_ ..............................................................-0.3V to +6VVCC to SGND............................................................-0.3V to +6VVCC, VDD to PGND ...................................................-0.3V to +6VSGND to PGND .....................................................-0.3V to +0.3VAll Other Pins to SGND...............................-0.3V to (VCC + 0.3V)

Continuous Power Dissipation (TA = +70°C)28-Pin SSOP (derate 9.5mW/°C above +70°C) ............762mW44-Pin Thin QFN (derate 27.0mW/°C above+70°C) ...2162mW

Operating Temperature Range ...........................-40°C to +85°CMaximum Junction Temperature .....................................+150°CStorage Temperature Range .............................-60°C to +150°CLead Temperature (soldering, 10s) .................................+300°C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SYSTEM SPECIFICATIONS

8 28

Input Voltage Range VIN Short IN and VCC together for +5V inputoperation

4.75 5.50V

Quiescent Supply Current IQ EN = VCC or SGND 4 10 mA

Efficiency η ILOAD = 52A (26A per phase) 90 %

OUTPUT VOLTAGE

No load 0.5952 0.6 0.6048

MAX5065 No load, VCC = +4.75V to +5.5Vor VIN = +8V to +28V

0.594 0.6 0.6064

No load 0.7936 0.8 0.8064SENSE+ to SENSE- Accuracy(Note 4)

MAX5067 No load, VCC = +4.75V to +5.5Vor VIN = +8V to +28V

0.792 0.8 0.808

V

STARTUP/INTERNAL REGULATOR

VCC Undervoltage Lockout UVLO VCC rising 4.0 4.15 4.5 V

VCC Undervoltage LockoutHysteresis

200 mV

VCC Output Accuracy VIN = +8V to +28V, ISOURCE = 0 to 80mA 4.85 5.1 5.30 V

MOSFET DRIVERS

Output Driver Impedance RON Low or high output 1 3 Ω

Output Driver Source/SinkCurrent

IDH_, IDL_ 4 A

Nonoverlap Time tNO CDH_/DL_ = 5nF 60 ns

OSCILLATOR AND PLL

CLKIN = SGND 238 250 262Switching Frequency fSW

CLKIN = VCC 475 500 525kHz

PLL Lock Range fPLL 125 600 kHz

PLL Locking Time tPLL 200 µs

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_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)(VCC = +5V, circuit of Figure 1, TA = -40°C to +85°C, unless otherwise noted. Typical specifications are at TA = +25°C.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

PHASE = VCC 115 120 125

PHASE = unconnected 85 90 95CLKOUT Phase Shift(At fSW = 125kHz)

φCLKOUT

PHASE = SGND 55 60 65

degrees

CLKIN Input Pulldown Current ICLKIN 3 5 7 µA

CLKIN High Threshold VCLKINH 2.4 V

CLKIN Low Threshold VCLKINL 0.8 V

CLKIN High Pulse Width tCLKIN 200 ns

PHASE High Threshold VPHASEH 4 V

PHASE Low Threshold VPHASEL 1 V

PHASE Input Bias Current IPHASEBIAS -50 +50 µA

CLKOUT Output Low Level VCLKOUTL ISINK = 2mA (Note 2) 100 mV

CLKOUT Output High Level VCLKOUTH ISOURCE = 2mA (Note 2) 4.5 V

CURRENT LIMIT

Average Current-Limit Threshold VCL CSP_ to CSN_ 45 48 51 mV

Reverse Current-Limit Threshold VCLR CSP_ to CSN_ -3.9 -0.2 mV

Cycle-by-Cycle Current Limit VCLPK CSP_ to CSN_ (Note 3) 90 112 130 mV

Cycle-by-Cycle OverloadResponse Time

tR VCSP_ to VCSN_ = +150mV 260 ns

CURRENT-SENSE AMPLIFIER

CSP_ to CSN_ Input Resistance RCS_ 4 kΩ

Common-Mode Range VCMR(CS) -0.3 +3.6 V

Input Offset Voltage VOS(CS) -1 +1 mV

Amplifier Gain AV(CS) 18 V/V

3dB Bandwidth f3dB 4 MHz

CURRENT-ERROR AMPLIFIER (TRANSCONDUCTANCE AMPLIFIER)

Transconductance gmca 550 µS

Open-Loop Gain AVOL(CE) No load 50 dB

DIFFERENTIAL VOLTAGE AMPLIFIER (DIFF)

Common-Mode Voltage Range VCMR(DIFF) -0.3 +1.0 V

DIFF Output Voltage VCM VSENSE+ = VSENSE- = 0 0.6 V

Input Offset Voltage VOS(DIFF) -1 +1 mV

Amplifier Gain AV(DIFF) 0.997 1 1.003 V/V

3dB Bandwidth f3dB CDIFF = 20pF 3 MHz

Minimum Output Current Drive IOUT(DIFF) 1.0 mA

SENSE+ to SENSE- InputResistance

RVS_ 50 100 kΩ

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4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)(VCC = +5V, circuit of Figure 1, TA = -40°C to +85°C, unless otherwise noted. Typical specifications are at TA = +25°C.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

VOLTAGE-ERROR AMPLIFIER (EAOUT)

Open-Loop Gain AVOL(EA) 70 dB

Unity-Gain Bandwidth fUGEA 3 MHz

EAN Input Bias Current IB(EA) VEAN = +2.0V -100 +100 nA

Error-Amplifier Output ClampingVoltage

VCLAMP(EA) With respect to VCM 810 918 mV

POWER-GOOD, PHASE FAILURE DETECTION, OVERVOLTAGE PROTECTION, AND THERMAL SHUTDOWN

VOVPGOOD goes low when VOUT is outside thiswindow

+6 +8 +10

PGOOD Trip Level (MAX5067)

VUVPGOOD goes low when VOUT is outside thiswindow

-12.5 -10 -8.5

%VOUT

PGOOD Output Low Level(MAX5067)

VPGLO ISINK = 4mA 0.2 V

PGOOD Output Leakage Current(MAX5067)

IPG PGOOD = VCC 1 µA

Phase Failure Trip Threshold(MAX5067)

VPHPGOOD goes low when CLP_ is higherthan VPH

2 V

OVPIN Trip Threshold (MAX5067) OVPTH With respect to SGND 0.792 0.8 0.808 V

OVPIN Input Resistance(MAX5067)

ROVPIN 190 280 370 kΩ

THERMAL SHUTDOWN

Thermal Shutdown TSHDN 150 °C

Thermal-Shutdown Hysteresis 8 °C

EN INPUT

EN Input Low Voltage VENL 1 V

EN Input High Voltage VENH 3 V

EN Pullup Current IEN 4.5 5 5.5 µA

Note 1: Specifications from -40°C to 0°C are guaranteed by characterization but not production tested.Note 2: Guaranteed by design. Not production tested.Note 3: See Peak-Current Comparator section.Note 4: Does not include an error due to finite error amplifier gain. See the Voltage-Error Amplifier section.

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_______________________________________________________________________________________ 5

EFFICIENCY vs. OUTPUT CURRENT ANDINTERNAL OSCILLATOR FREQUENCY

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IOUT (A)

η (%

)

4844403632282420161284

50

60

70

80

90

100

400 52

f = 500kHz

f = 250kHz

VIN = +5VVOUT = +1.8V

EFFICIENCY vs. OUTPUT CURRENTAND INPUT VOLTAGE

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2

IOUT (A)

η (%

)

4844403632282420161284

50

40

30

20

10

60

70

80

90

100

00 52

VIN = +12V

VIN = +5V

VOUT = +1.8VfSW = 250kHz

EFFICIENCY vs. OUTPUT CURRENTAND INPUT VOLTAGE

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3

OUTPUT CURRENT (A)

η (%

)

484436 4012 16 20 24 28 324 8

10

20

30

40

50

60

70

80

90

100

00 52

VIN = +12V

VIN = +5V

VOUT = 1VfSW = 250kHz

EFFICIENCY vs. OUTPUT CURRENT

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IOUT (A)

η (%

)

4844403632282420161284

50

40

30

20

10

60

70

80

90

100

00 52

VIN = +24VVOUT = +1.8VfSW = 125kHz

EFFICIENCY vs. OUTPUT CURRENTAND OUTPUT VOLTAGE

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5

OUTPUT CURRENT (A)

η (%

)

4844403632282420161284

50

40

30

20

10

60

70

80

90

100

00 52

VOUT = +1V

VOUT = +1.5VVOUT = +1.8V

VIN = +12VfSW = 250kHz

EFFICIENCY vs. OUTPUT CURRENTAND OUTPUT VOLTAGE

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OUTPUT CURRENT (A)

η (%

)

4844403632282420161284

50

40

30

20

10

60

70

80

90

100

00 52

VOUT = +1V

VOUT = +1.5V VOUT = +1.8V

VIN = +12VfSW = 500kHz

SUPPLY CURRENTvs. FREQUENCY AND INPUT VOLTAGE

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FREQUENCY (kHz)

I CC

(mA)

550500400 450200 250 300 350150

6.57.07.58.08.59.09.5

10.010.511.011.512.0

6.0100 600

VIN = +24V

VIN = +12V

VIN = +5V EXTERNALCLOCKNO DRIVER LOAD

SUPPLY CURRENTvs. TEMPERATURE AND FREQUENCY

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8

TEMPERATURE (°C)

I CC

(mA)

603510-15

10

20

30

40

50

60

70

80

90

100

0-40 85

250kHz

125kHz

VIN = +12VCDL_ = 22nFCDH_ = 8.2nF

SUPPLY CURRENTvs. LOAD CAPACITANCE PER DRIVER

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CDRIVER (nF)

I CC

(mA)

13117 953

10

20

30

40

50

60

70

80

90

100

01 15

VIN = +12VfSW = 250kHz

Typical Operating Characteristics(Circuit of Figure 1. TA = +25°C, unless otherwise noted.)

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Typical Operating Characteristics (continued)(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)

CURRENT-SENSE THRESHOLDvs. OUTPUT VOLTAGE

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VOUT (V)

(VCS

P_ -

V CSN

_) (m

V)

1.71.61.4 1.51.2 1.31.1

46

47

48

49

50

51

52

53

54

55

451.0 1.8

PHASE 2

PHASE 1

10

0.14.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5

OVERVOLTAGE THRESHOLD (PGOOD)vs. INPUT VOLTAGE

1

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VIN (V)

V OV

(V)

VOUT = +0.8V

VOUT = +3.3V

10

4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5

UNDERVOLTAGE THRESHOLD (PGOOD)vs. INPUT VOLTAGE

1

0.1

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2

VIN (V)

V UV

(V)

VOUT = +0.8V

VOUT = +3.3V

1.50

1.60

1.55

1.75

1.70

1.65

1.80

1.85

1.90

0 8 124 16 20 24 28 32 36 40 44 48 52

OUTPUT VOLTAGE vs. OUTPUT CURRENTAND ERROR AMP GAIN (RF/RIN)

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3

ILOAD (A)

V OUT

(V)

RF/RIN = 40RF/RIN = 20

RF/RIN = 7.5

RF/RIN = 10

DIFFERENTIAL AMPLIFIER BANDWIDTHMAX5065/67 toc14

FREQUENCY (MHz)

GAIN

(V/V

)

PHAS

E (d

eg)

10.1

0.5

1.0

1.5

2.0

2.5

3.0

3.5

00.01 10

-225

-270

-180

-135

-90

-45

0

45

90

PHASE

GAIN

DIFF OUTPUT ERRORvs. SENSE+ TO SENSE- VOLTAGE

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5

∆VSENSE (V)

ERRO

R (%

)

1.91.81.1 1.2 1.3 1.5 1.61.4 1.7

0.025

0.050

0.075

0.100

0.125

0.150

0.175

0.200

01.0 2.0

VIN = +12VNO DRIVER

VCC LOAD REGULATIONvs. INPUT VOLTAGE

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ICC (mA)

V CC

(V)

13512015 30 45 75 9060 105

4.85

4.90

4.95

5.00

5.05

5.10

5.15

5.20

4.800 150

VIN = +24V

VIN = +12V

VIN = +8V

DC LOAD

VCC LINE REGULATION

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VIN (V)

V CC

(V)

262420 2212 14 16 1810

4.80

4.85

4.90

4.95

5.00

5.05

5.10

5.15

5.20

5.25

4.758 28

ICC = 0

ICC = 40mA

VCC LINE REGULATIONM

AX50

65/6

7 to

c18

VIN (V)

V CC

(V)

13129 10 11

4.80

4.85

4.90

4.95

5.00

5.05

5.10

5.15

5.20

5.25

4.758

ICC = 80mA

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DRIVER RISE TIMEvs. DRIVER LOAD CAPACITANCE

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CDRIVER (nF)

t R (n

s)

312616 21116

102030405060708090

100110120

01 36

DL_

DH_

VIN = +12VfSW = 250kHz

DRIVER FALL TIMEvs. DRIVER LOAD CAPACITANCE

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CDRIVER (nF)

t R (n

s)

312616 21116

102030405060708090

100110120

01 36

DL_

DH_

VIN = +12VfSW = 250kHz

100ns/div

HIGH-SIDE DRIVER (DH_)SINK AND SOURCE CURRENT

DH_1.6A/div

MAX5065/67 toc21

VIN = +12VCDH_ = 22nF

100ns/div

LOW-SIDE DRIVER (DL_)SINK AND SOURCE CURRENT

DL_1.6A/div

MAX5065/67 toc22

VIN = +12VCDL_ = 22nF

100µs/div

PLL LOCKING TIME250kHz TO 350kHz AND

350kHz TO 250kHz

CLKOUT5V/div

MAX5065/67 toc23

PLLCMP200mV/div

VIN = +12VNO LOAD

350kHz

250kHz

0

100µs/div

PLL LOCKING TIME250kHz TO 500kHz AND

500kHz TO 250kHz

CLKOUT5V/div

MAX5065/67 toc24

PLLCMP200mV/div

0

VIN = +12VNO LOAD

500kHz

250kHz

100µs/div

PLL LOCKING TIME250kHz TO 150kHz AND

150kHz TO 250kHz

CLKOUT5V/div

MAX5065/67 toc25

PLLCMP200mV/div

0

VIN = +12VNO LOAD

250kHz

150kHz

Typical Operating Characteristics (continued)(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)

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Typical Operating Characteristics (continued)(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)

40ns/div

LOW-SIDE DRIVER (DL_)RISE TIME

MAX5065/67 toc28

DL_2V/div

VIN = +12VCDL_ = 22nF

40ns/div

LOW-SIDE DRIVER (DL_)FALL TIME

MAX5065/67 toc29

DL_2V/div

VIN = +12VCDL_ = 22nF

500ns/div

OUTPUT RIPPLEMAX5065/67 toc30

VOUT(AC-COUPLED)10mV/div

VIN = +12VVOUT = +1.75VIOUT = 52A

2ms/div

INPUT STARTUP RESPONSEMAX5065/67 toc31

VIN 5V/div

VIN = +12VVOUT = +1.75VIOUT = 52A

VPGOOD1V/div

VOUT1V/div

40ns/div

HIGH-SIDE DRIVER (DH_)RISE TIME

MAX5065/67 toc26

VIN = +12VCDH_ = 22nF

DH_2V/div

40ns/div

HIGH-SIDE DRIVER (DH_)FALL TIME

MAX5065/67 toc27

DH_2V/div

VIN = +12VCDH_ = 22nF

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1ms/div

ENABLE STARTUP RESPONSEMAX5065/67 toc32

VEN 2V/div

VPGOOD1V/div

VOUT1V/div

VIN = +12VVOUT = +1.75VIOUT = 52A

40µs/div

LOAD-TRANSIENT RESPONSEMAX5065/67 toc33

VIN = +12VVOUT = +1.75VISTEP = 8A TO 52AtRISE = 1µs

VOUT50mV/div

REVERSE CURRENT SINKvs. TEMPERATURE

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TEMPERATURE (°C)

I REV

ERSE

(A)

603510-15

2.4

2.5

2.6

2.7

2.8

2.3-40 85

VEXTERNAL = +3.3V

VEXTERNAL = +2V

VIN = +12VVOUT = 1.5V R1 = R2 = 1.5mΩ

200µs/div

REVERSE CURRENT SINK AT INPUT TURN-ON(VIN = 12V, VOUT = 1.5V, VEXTERNAL = 2.5V)

MAX5065/67 toc35

REVERSECURRENT5A/div0A

R1 = R2 = 1.5mΩ

200µs/div

REVERSE CURRENT SINK AT INPUT TURN-ON(VIN = 12V, VOUT = 1.5V, VEXTERNAL = 3.3V)

MAX5065/67 toc36

REVERSECURRENT10A/div

0A

R1 = R2 = 1.5mΩ

200µs/div

REVERSE CURRENT SINK AT ENABLE TURN-ON(VIN = 12V, VOUT = 1.5V, VEXTERNAL = 2.5V)

MAX5065/67 toc37

REVERSECURRENT5A/div

0A

R1 = R2 = 1.5mΩ

200µs/div

REVERSE CURRENT SINK AT ENABLE TURN-ON(VIN = 12V, VOUT = 1.5V, VEXTERNAL = 3.3V)

MAX5065/67 toc38

REVERSECURRENT10A/div

0A

R1 = R2 = 1.5mΩ

Typical Operating Characteristics (continued)(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)

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Pin DescriptionPIN

MAX5065 MAX5067NAME FUNCTION

1, 13 39, 16CSP2,CSP1

Current-Sense Differential Amplifier Positive Inputs. Sense the inductor current. The differentialvoltage between CSP_ and CSN_ is amplified internally by the current-sense amplifier gain of18.

2, 14 40, 17CSN2,CSN1

Current-Sense Differential Amplifier Negative Inputs. Together with CSP_, sense the inductorcurrent.

3 41 PHASEPhase-Shift Setting Input. Connect PHASE to VCC for 120°, leave PHASE unconnected for 90°,or connect PHASE to SGND for 60° of phase shift between the rising edge of CLKOUT andCLKIN/DH1.

4 42 PLLCMPExternal Loop-Compensation Input. Connect compensation network for the phase-locked loop(see the Phase-Locked Loop section).

5, 7 43, 7CLP2,CLP1

Current-Error Amplifier Outputs. Compensate the current loop by connecting an RC network toground.

6 5, 20, 35 SGND Signal Ground. Ground connection for the internal control circuitry.

8 10 SENSE+Differential Output-Voltage-Sensing Positive Input. Used to sense a remote load. The MAX5065and MAX5067 regulate the difference between SENSE+ and SENSE- according to the factorypreset reference voltage of +0.6V and +0.8V, respectively.

9 11 SENSE-Differential Output Voltage-Sensing Negative Input. Used to sense a remote load. ConnectSENSE- to VOUT- or PGND at the load.

10 12 DIFFDifferential Remote-Sense Amplifier Output. DIFF is the output of a precision unity-gainamplifier.

11 13 EANVoltage-Error Amplifier Inverting Input. Receives a signal from the output of the differentialremote-sense amplifier. Referenced to SGND.

12 14 EAOUTVoltage-Error Amplifier Output. Connect to the external gain-setting feedback resistor. Theexternal error amplifier gain-setting resistors determine the amount of adaptive voltagepositioning.

15 19 ENOutput Enable. A logic-low shuts down the power drivers. EN has an internal 5µA pullupcurrent.

16, 26 22, 34BST1,BST2

Boost Flying-Capacitor Connection. Reservoir capacitor connection for the high-side FET driversupply. Connect a 0.47µF ceramic capacitor between BST_ and LX_.

17, 25 23, 32DH1,DH2

High-Side Gate-Driver Outputs. Drive the gate of the high-side MOSFET.

18, 24 24, 31 LX1, LX2Inductor Connection. Source connection for the high-side MOSFETs. Also serve as the returnterminal for the high-side driver.

19, 23 25, 30 DL1, DL2 Low-Side Gate-Driver Outputs. Synchronous MOSFET gate drivers for the two phases.

20 27 VCCInternal +5V Regulator Output. VCC is derived internally from the IN voltage. Bypass to SGNDwith 4.7µF and 0.1µF ceramic capacitors in parallel.

21 28 INSupply Voltage Connection. Connect IN to VCC for a +5V system. Connect the unregulatedpower source to IN through an RC lowpass filter comprised of a 2.2Ω resistor and a 0.1µFceramic capacitor.

22 29 PGNDPower Ground. Connect the VCC bypass capacitors, input capacitors, output capacitors, andlow-side synchronous MOSFET source to PGND.

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Detailed DescriptionThe MAX5065/MAX5067 average-current-mode PWMcontrollers drive two out-of-phase buck converter chan-nels. Average-current-mode control improves currentsharing between the channels while minimizing compo-nent derating and size. Parallel multiple MAX5065/MAX5067 regulators to increase the output currentcapacity. For maximum ripple rejection at the input, setthe phase shift between phases to 90° for two paral-leled converters, or 60° for three paralleled converters.Paralleling the MAX5065/MAX5067s improves designflexibility in applications requiring upgrades (higherload).

Dual-phase converters with an out-of-phase lockingarrangement reduce the input and output capacitor ripple current, effectively multiplying the switching fre-quency by the number of phases. Each phase of theMAX5065/MAX5067 consists of an inner average cur-rent loop controlled by a common outer-loop voltage-error amplifier (VEA). The combined action of the twoinner current loops and the outer voltage loop correctsthe output voltage errors and forces the phase currentsto be equal. Program the output voltage from +0.6V to

+3.3V (MAX5065) and +0.8V to +3.3V (MAX5067) usinga resistive-divider at SENSE+ and SENSE-.

VIN, VCC, VDD The MAX5065/MAX5067 accept a wide input voltagerange of +4.75V to +5.5V or +8V to +28V. All internalcontrol circuitry operates from an internally regulatednominal voltage of +5V (VCC). For input voltages of +8Vor greater, the internal VCC regulator steps the voltagedown to +5V. The VCC output voltage regulates to +5Vwhile sourcing up to 80mA. Bypass VCC to SGND with4.7µF and 0.1µF low-ESR ceramic capacitors for high-frequency noise rejection and stable operation (Figures1, 2, and 3).

Calculate power dissipation in the MAX5065/MAX5067as a product of the input voltage and the total VCC reg-ulator output current (ICC). ICC includes quiescent cur-rent (IQ) and gate-drive current (IDD):

PD = VIN x ICC

ICC = IQ + fSW x (QG1 + QG2 + QG3 + QG4)

Pin Description (continued)PIN

MAX5065 MAX5067NAME FUNCTION

27 36 CLKOUTOscillator Output. CLKOUT is phase-shifted from CLKIN by the amount determined by thePHASE input. Use CLKOUT to parallel additional MAX5065/MAX5067s.

28 38 CLKIN

CMOS Logic Clock Input. Drive CLKIN with a frequency range between 125kHz and 600kHz orconnect to VCC or SGND. Connect CLKIN to SGND to set the internal oscillator to 250kHz orconnect to VCC to set the internal oscillator to 500kHz. CLKIN has an internal 5µA pulldowncurrent.

— 6 OVPINOvervoltage Protection Circuit Input. Connect OVPIN to the center of the resistive-dividerbetween VOUT and GND. When OVPIN exceeds +0.8V with respect to SGND, OVPOUT latchesDH_ low and DL_ high. Toggle EN low to high or recycle the power to reset the latch.

— 8 OVPOUTOvervoltage Protection Output. Use the OVPOUT active-high, push-pull output to trigger asafety device such as an SCR.

— 9 PGOOD

Power-Good Output. The open-drain, active-low PGOOD output goes low when the outputvoltage falls out of regulation or a phase failure is detected. The power-good window-comparator thresholds are +8% and -10% of the output voltage. Forcing EN low also forcesPGOOD low.

1, 2, 3, 4,15, 18,21, 33,37, 44

N.C. No Connection. Not internally connected.

— 26 VDD

Supply Voltage for Low-Side and High-Side Drivers. VCC powers VDD. Connect a parallelcombination of 0.1µF and 1µF ceramic capacitors to PGND and a 1Ω resistor to VCC to filterout the high peak currents of the driver from the internal circuitry.

(1)

(2)

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12 ______________________________________________________________________________________

MAX5065

IN

EN

PHASE 1

CSP1DRV_VCC

RAMP1

GMIN

CLK

CLP1

CSN1

SHDNBST1

DL1

LX1

DH1

VCC

TO INTERNAL CIRCUITS

TO INTERNAL CIRCUITS

CSP1

CSN1

CLP1

PHASE 2

CSP2

DRV_VCC

GMIN

CLK

CLP2

CSN2

SHDN

BST2

DL2

LX2

DH2

CSP2

CSN2

CLP2

PHASE-LOCKED

LOOP

RAMPGENERATOR

RAMP2

CLKIN

PHASE

CLKOUT

PLLCMP

DIFFAMP

ERRORAMP

SENSE-

SENSE+

DIFF

EAN

EAOUT

PGND

PGND

PGND

SGND

VREF = 0.6V + VCM

+5VLDO

REGULATOR

UVLOPOR

TEMP SENSOR

0.6V

Functional Diagrams

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Dual-Phase, +0.6V to +3.3V Output Parallelable,Average-Current-Mode Controllers

______________________________________________________________________________________ 13

MAX5067

IN

EN

PHASE 1

CSP1DRV_VCC

RAMP1

GMIN

CLK

CLP1

CSN1

SHDNBST1

DL1

LX1

DH1

VCC

VDDTO INTERNAL CIRCUITS

CSP1

CSN1

CLP1

PHASE 2

CSP2

DRV_VCC

GMIN

CLK

CLP2

CSN2

SHDN

BST2

DL2

LX2

DH2

OVPOUT

PGOOD

CSP2

CSN2

CLP2OVPIN

PHASE-LOCKED

LOOP

RAMPGENERATOR

RAMP2

POWER-GOOD

GENERATORCLP2

CLP1

VREF

DIFF

CLKIN

PHASE

CLKOUT

PLLCMP

DIFFAMP

ERRORAMP

SENSE-

SENSE+

DIFF

EAN

EAOUT

PGND

PGND

PGND

SGND

VREF = 0.8V + VCM

+5VLDO

REGULATOR

UVLOPOR

TEMP SENSOR

+0.6V

0.8V OVPCOMP

N

Functional Diagrams (continued)

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Dual-Phase, +0.6V to +3.3V Output Parallelable,Average-Current-Mode Controllers

14 ______________________________________________________________________________________

MAX

5067

Q4Q3

C39

C40

R3

D2

Q2

D1

V IN

C8 C11

Q1

V IN

V CC

D4D3

C41

C12

C38

C3–C

7

C14

C15

C16

C25

C26,

C30,

C37

LOAD

L2R2

L1R1

DH1

LX1

DL1

BST1 V D

D

V CC

DH2

LX2

DL2

BST2

CSP2

CSN2

PGOO

DPH

ASE

SGND

PGND

CLP2

CLP1

R11

PGOO

DV C

C

R6

C35

C36

R5 C33

C34

C42

C1, C

2

R13

V CC

C31

C32

R4

CSP1

CSN1

SENS

E+SE

NSE-

INCL

KIN

PLLC

MP

EN

R fR IN

R12

C43

V IN

EAOU

T

EAN

DIFF

OVPI

N

OVPO

UT

C13

IN

IN

C44

RA RB

RH RL

V CC

R X

V OUT

= +

0.8V

TO

+3.3

V AT

52A

V IN

= +5

V

Figure 1. Typical Application Circuit, VIN = +5V

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Dual-Phase, +0.6V to +3.3V Output Parallelable,Average-Current-Mode Controllers

______________________________________________________________________________________ 15

MAX

5067

Q4Q3

C39

C40

R3

D2

Q2

D1

V IN

C8–

C11

Q1

V IN

V CC

D4D3

C41

C12

C38

C3–C

7

C14,

C15

C16–

C25

C26–

C30,

C37

LOAD

L2R2

L1R1

DH1

LX1

DL1

BST1 V D

D

V CC

DH2

LX2

DL2

BST2

CSP2

CSN2

PGOO

DPH

ASE

SGND

PGND

CLP2

CLP1

R11

PGOO

DV C

C

R6

C35

C36

R5 C33

C34

C42

C1, C

2

R13

V CC

C31

C32

R4

CSP1

CSN1

SENS

E+SE

NSE-

INCL

KIN

PLLC

MP

EN

R fR IN

R12

C43

V IN

EAOU

T

EAN

DIFF

OVPI

N

OVPO

UT

C13

C44

RA RB

RH RL

V CC

R X

V OUT

= +

1.8V

AT

52A

V IN

= +8

V TO

+28

V

NOTE

: SEE

TABL

E 1

FOR

COM

PONE

NT V

ALUE

S.

Figure 2. Typical VRM Application Circuit, VIN = +8V to +28V

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Dual-Phase, +0.6V to +3.3V Output Parallelable,Average-Current-Mode Controllers

16 ______________________________________________________________________________________

CLKIN

PLLCMP

PGND

PHASE

DL2

LX2

DH2

DL1

LX1

DH1

VCC

EAOUT

EAN

DIFF

EN

CSP2

CSN2

CSP1

CSN1

MAX5065

3

R1

C39

VIN = +12V

C1,C2

21

15

IN

C25

C26

R4

R7

R8

R6C29

C30

R5C27

C28

SGND

CLP2

CLP1 Q2

Q1

D2

Q2D1

VIN

Q1

VIN

D4

D3

C32

C12

C31

C3–C7

L2 R3

L1 R2

C13

C8–C11 C14,C15

C16–C24,C33

LOAD

+1.8V AT 60AVOUT

SENSE-

SENSE+

17

18

19

16

20

25

24

23

26

9

8

14

13

1

2

BST1

VCC

28

4

10

11

12

7

5

6

22

BST2

RH

RL

VCC

RX

C34

Figure 3. MAX5065 Typical Application Circuit

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where, QG1, QG2, QG3, and QG4 are the total gatecharge of the low-side and high-side externalMOSFETs, IQ is 4mA (typ), and fSW is the switching fre-quency of each individual phase.

For applications utilizing a +5V input voltage, disablethe VCC regulator by connecting IN and VCC together.

Undervoltage Lockout (UVLO)/Soft-StartThe MAX5065/MAX5067 include an undervoltage lock-out with hysteresis and a power-on reset circuit for con-verter turn-on and monotonic rise of the output voltage.The UVLO threshold is internally set between +4.0Vand +4.5V with a 200mV hysteresis. Hysteresis atUVLO eliminates “chattering” during startup.

Most of the internal circuitry, including the oscillator,turns on when the input voltage reaches +4V. TheMAX5065/MAX5067 draw up to 4mA of current beforethe input voltage reaches the UVLO threshold.

The compensation network at the current-error ampli-fiers (CLP1 and CLP2) provides an inherent soft-start ofthe output voltage. It includes a parallel combination ofcapacitors (C34, C36) and resistors (R5, R6) in serieswith other capacitors (C33, C35) (see Figures 1 and 2).The voltage at CLP_ limits the maximum current avail-able to charge output capacitors. The capacitor onCLP_ in conjunction with the finite output-drive currentof the current-error amplifier yields a finite rise time forthe output current and thus the output voltage.

Internal OscillatorThe internal oscillator generates the 180° out-of-phaseclock signals required by the pulse-width modulation(PWM) circuits. The oscillator also generates the 2VP-Pvoltage ramp signals necessary for the PWM compara-tors. Connect CLKIN to SGND to set the internal oscillatorfrequency to 250kHz or connect CLKIN to VCC to set theinternal oscillator to 500kHz.

CLKIN is a CMOS logic clock input for the phase-locked loop (PLL). When driven externally, the internaloscillator locks to the signal at CLKIN. A rising edge atCLKIN starts the ON cycle of the PWM. Ensure that theexternal clock pulse width is at least 200ns. CLKOUTprovides a phase-shifted output with respect to the ris-ing edge of the signal at CLKIN. PHASE sets theamount of phase shift at CLKOUT. Connect PHASE toVCC for 120° of phase shift, leave PHASE unconnectedfor 90° of phase shift, or connect PHASE to SGND for60° of phase shift with respect to CLKIN.

The MAX5065/MAX5067 require compensation on PLLCMP even when operating from the internal oscillator.The device requires an active PLL to generate the properclock signal required for PWM operation.

Control LoopThe MAX5065/MAX5067 use an average-current-modecontrol scheme to regulate the output voltage (Figure4). The main control loop consists of an inner currentloop and an outer voltage loop. The inner loop controlsthe output currents (IPHASE1 and IPHASE2) while theouter loop controls the output voltage. The inner currentloop absorbs the inductor pole reducing the order ofthe outer voltage loop to that of a singlepole system.

The current loop consists of a current-sense resistor(RS), a current-sense amplifier (CA_), a current-erroramplifier (CEA_), an oscillator providing the carrierramp, and a PWM comparator (CPWM_). The precisionCA_ amplifies the sense voltage across RS by a factorof 18. The inverting input to the CEA_ senses the CA_output. The CEA_ output is the difference between thevoltage-error amplifier output (EAOUT) and the gained-up voltage from the CA_. The RC compensation net-work connected to CLP1 and CLP2 provides externalfrequency compensation for the respective CEA_. Thestart of every clock cycle enables the high-side driversand initiates a PWM ON cycle. Comparator CPWM_compares the output voltage from the CEA_ with a 0 to+2V ramp from the oscillator. The PWM ON cycle termi-nates when the ramp voltage exceeds the error voltage.

The outer voltage control loop consists of the differen-tial amplifier (DIFF AMP), reference voltage, and VEA.The unity-gain differential amplifier provides true differ-ential remote sensing of the output voltage. The differ-ential amplifier output connects to the inverting input(EAN) of the VEA. The noninverting input of the VEA isinternally connected to an internal precision referencevoltage. The MAX5067 reference voltage is set to +0.8Vand the MAX5065 reference is set to +0.6V. The VEAcontrols the two inner current loops (Figure 4). Use aresistive feedback network to set the VEA gain asrequired by the adaptive voltage-positioning circuit(see the Adaptive Voltage Positioning section).

Current-Sense AmplifierThe differential current-sense amplifier (CA_) provides aDC gain of 18. The maximum input offset voltage of thecurrent-sense amplifier is 1mV and the common-modevoltage range is -0.3V to +3.6V. The current-sense ampli-fier senses the voltage across a current-sense resistor.

Peak-Current ComparatorThe peak-current comparator provides a path for fastcycle-by-cycle current limit during extreme fault condi-tions such as an output inductor malfunction (Figure 5).Note that the average current-limit threshold of 48mVstill limits the output current during short-circuit condi-tions. To prevent inductor saturation, select an output

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18 ______________________________________________________________________________________

inductor with a saturation current specification greaterthan the average current limit (48mV). Proper inductorselection ensures that only extreme conditions trip thepeak-current comparator, such as a cracked outputinductor. The 112mV voltage threshold for triggeringthe peak-current limit is twice the full-scale averagecurrent-limit voltage threshold. The peak-current com-parator has a delay of only 260ns.

Current-Error AmplifierEach phase of the MAX5065/MAX5067 has a dedicatedtransconductance current-error amplifier (CEA_) with atypical gm of 550µS and 320µA output sink and sourcecurrent capability. The current-error amplifier outputs,CLP1 and CLP2, serve as the inverting input to thePWM comparator. CLP1 and CLP2 are externallyaccessible to provide frequency compensation for theinner current loops (Figure 4). Compensate CEA_ sothe inductor current down slope, which becomes the

up slope to the inverting input of the PWM comparator,is less than the slope of the internally generated voltageramp (see the Compensation section).

PWM Comparator and R-S Flip-FlopThe PWM comparator (CPWM) sets the duty cycle foreach cycle by comparing the output of the current-erroramplifier to a 2VP-P ramp. At the start of each clockcycle, an R-S flip-flop resets and the high-side driver(DH_) turns on. The comparator sets the flip-flop assoon as the ramp voltage exceeds the CLP_ voltage,thus terminating the ON cycle (Figure 5).

Differential AmplifierThe differential amplifier (DIFF AMP) facilitates outputvoltage remote sensing at the load (Figure 4). It pro-vides true differential output voltage sensing whilerejecting the common-mode voltage errors due to high-current ground paths. Sensing the output voltage

DRIVE 2

DRIVE 1CPWM1

CPWM2

CEA1

CEA2

VEA

DIFFAMP

CA1

CA2

VREF

CLP2

CSP2

CSN2

CLP1

CSN1

CSP1

SENSE+

SENSE-

VIN

VIN

LOADCOUT

VOUT

RIN*

RF*

RS

RS

IPHASE1

IPHASE2

RCF

CCFF

CCF

RCF

CCCF

CCF

*RF AND RIN ARE EXTERNAL.

MAX5065/MAX5067

Figure 4. MAX5065/MAX5067 Control Loop

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directly at the load provides accurate load voltagesensing in high-current environments. The VEA pro-vides the difference between the differential amplifieroutput (DIFF) and the desired output voltage. The dif-ferential amplifier has a bandwidth of 3MHz. The differ-ence between SENSE+ and SENSE- regulates to +0.6Vfor the MAX5065 and regulates to +0.8V for theMAX5067. Connect SENSE+ to the center of the resis-tive-divider from the output to SENSE-.

Voltage-Error Amplifier The VEA sets the gain of the voltage control loop anddetermines the error between the differential amplifieroutput and the internal reference voltage (VREF).

The VEA output clamps to +0.9V relative to VCM(+0.6V), thus limiting the average maximum currentfrom individual phases. The maximum average current-limit threshold for each phase is equal to the maximumclamp voltage of the VEA divided by the gain (18) ofthe current-sense amplifier. This results in accurate set-tings for the average maximum current for each phase.Set the VEA gain using RF and RIN for the amount ofoutput voltage positioning required within the rated cur-rent range as discussed in the Adaptive VoltagePositioning section (Figure 4).

where RH and RL are the feedback resistor network

(Figures 1, 2). VREF = 0.6V (MAX5065) or 0.8V(MAX5067).

Some applications require VOUT equal to VOUT(NOM) atno load. To ensure that the output voltage does notexceed the nominal output voltage (VOUT(NOM)), add aresistor RX from VCC to EAN.

Use the following equations to calculate the value of RX.

For MAX5065:

For MAX5067:

Adaptive Voltage PositioningPowering new-generation processors requires newtechniques to reduce cost, size, and power dissipation.Voltage positioning reduces the total number of outputcapacitors to meet a given transient response require-ment. Setting the no-load output voltage slightly higherthan the output voltage during nominally loaded condi-tions allows a larger downward voltage excursion whenthe output current suddenly increases. Regulating at alower output voltage under a heavy load allows a largerupward-voltage excursion when the output current sud-denly decreases. A larger allowed, voltage-step excur-sion reduces the required number of output capacitors

R VR

VX CCF= − ×[ . ]

.1 4

0 8

R VR

VX CCF= − ×[ . ]

.1 2

0 6

VR

R

R R

RVOUT NL

IN

F

H L

LREF( ) = +

×

+

×1

2 x fs (V/s)

RAMP

CLK

CSP_

CSN_

GMIN

SHDN

CLP_

DRV_VCC

BST_

DH_

LX_

DL_

PGND

AV = 18

PWMCOMPARATOR

PEAK-CURRENTCOMPARATOR

112mV

S

R

Q

Q

Gm =500µS

Figure 5. Phase Circuit (Phase 1/Phase 2)

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or allows for the use of higher ESR capacitors.

Voltage positioning may require the output to regulateaway from a center value. Define the center value as thevoltage where the output drops (∆VOUT/2) at one half themaximum output current (Figure 6).

Set the voltage-positioning window (∆VOUT) using theresistive feedback of the VEA. Use the following equa-tions to calculate the voltage-positioning window for theMAX5065/MAX5067:

where RIN and RF are the input and feedback resistors ofthe VEA, GC is the current-loop transconductance, andRS is the current-sense resistor.

Phase-Locked Loop: Operation andCompensation

The PLL synchronizes the internal oscillator to theexternal frequency source when driving CLKIN.Connecting CLKIN to VCC or SGND forces the PWMfrequency to default to the internal oscillator frequencyof 500kHz or 250kHz, respectively. The PLL uses aconventional architecture consisting of a phase detec-tor and a charge pump capable of providing 20µA ofoutput current. Connect an external series combinationcapacitor (C31) and resistor (R4) and a parallel capaci-tor (C32) from PLLCMP to SGND to provide frequencycompensation for the PLL (Figure 1). The pole-zero pair

compensation provides a zero defined by 1 / [R4 x(C31 + C32)] and a pole defined by 1 / (R4 x C32). Usethe following typical values for compensating the PLL:

R4 = 7.5kΩ, C31 = 4.7nF, C32 = 470pF. If changing thePLL frequency, expect a finite locking time of approxi-mately 200µs.

The MAX5065/MAX5067 require compensation on PLLCMP even when operating from the internal oscilla-tor. The device requires an active PLL in order to gen-erate the proper internal PWM clocks.

MOSFET Gate Drivers (DH_, DL_)The high-side (DH_) and low-side (DL_) drivers drivethe gates of external N-channel MOSFETs (Figures 1, 2,and 3). The drivers’ high-peak sink and source currentcapability provides ample drive for the fast rise and falltimes of the switching MOSFETs. Faster rise and falltimes result in reduced cross-conduction losses. Formodern CPU voltage-regulating module applicationswhere the duty cycle is less than 50%, choose high-side MOSFETs (Q1 and Q3) with a moderate RDS(ON)and a very low gate charge. Choose low-sideMOSFETs (Q2 and Q4) with very low RDS(ON) andmoderate gate charge.

The driver block also includes a logic circuit that providesan adaptive nonoverlap time to prevent shoot-throughcurrents during transition. The typical nonoverlap time is60ns between the high-side and low-side MOSFETs.

BST_The MAX5067 uses VDD to power the low- and high-side MOSFET drivers. The high-side drivers derive theirpower through a bootstrap capacitor and VDD suppliespower internally to the low-side drivers. Connect a0.47µF low-ESR ceramic capacitor between BST_ andLX_. Bypass VCC to SGND with 4.7µF and 0.1µF low-ESR ceramic capacitors in parallel. Reduce the PCboard area formed by these capacitors, the rectifierdiodes between VCC and the boost capacitor, theMAX5065/MAX5067, and the switching MOSFETs.

Overload ConditionsAverage-current-mode control has the ability to limit theaverage current sourced by the converter during a faultcondition. When a fault condition occurs, the VEA out-put clamps to +0.9V with respect to the common-modevoltage (VCM = +0.6V) and is compared with the outputof the current-sense amplifiers (CA1 and CA2) (seeFigure 4). The current-sense amplifier’s gain of 18 limitsthe maximum current in the inductor or sense resistor toILIMIT = 50mV/RS.

GR

CS

= 0 05.

∆VI R

G RR R

ROUTOUT IN

C F

H L

L= ×

× ×× +

2

(6)

(7)

LOAD (A)

VCNTR

NO LOAD 1/2 LOAD FULL LOAD

VOLTAGE-POSITIONING WINDOW

VCNTR + ∆VOUT/2

VCNTR - ∆VOUT/2

Figure 6. Defining the Voltage-Positioning Window

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ProtectionThe MAX5067 includes output overvoltage protection(OVP), undervoltage protection (UVP), phase failure,and overload protection to prevent damage to the pow-ered electronic circuits.

Overvoltage Protection (MAX5067)The OVP comparator compares the OVPIN input to theovervoltage threshold (Figure 7). The overvoltagethreshold is typically +0.8V. A detected overvoltageevent latches the comparator output forcing the powerstage into the OVP state. In the OVP state, the high-side MOSFETs turn off and the low-side MOSFETs latchon. Use the OVPOUT high-current output driver to turnon an external crowbar SCR. When the crowbar SCRturns on, a fuse must blow or the source current for theMAX5067 regulator must be limited to prevent furtherdamage to the external circuitry. Connect the SCRclose to the input source and after the fuse. Use anSCR large enough to handle the peak I2t energy due tothe input and output capacitors discharging and thecurrent sourced by the power-source output. ConnectDIFF to OVPIN for differential output sensing and over-voltage protection. Add an RC delay to reduce the sen-sitivity of the overvoltage circuit and avoid nuisancetripping of the converter (Figures 1, 2). Connect a resis-tor-divider from the load to SGND to set the OVP outputvoltage.

Power-Good Generator (MAX5067)The PGOOD output is high if all of the following condi-tions are met (Figure 8):

1) The output is within 90% to 108% of the pro-grammed output voltage.

2) Both phases are providing current.

3) EN is high.

A window comparator compares the differential amplifieroutput (DIFF) against 1.08 times the set output voltagefor overvoltage and 0.90 times the set output voltage forundervoltage monitoring. The phase-failure comparatordetects a phase failure by comparing the current-error-amplifier output (CLP_) with a 2.0V reference.

Use a 10kΩ pullup resistor from PGOOD to a voltagesource less than or equal to VCC. An output voltageoutside the comparator window or a phase-failure con-dition forces the open-drain output low. The open-drainMOSFET sinks 4mA of current while maintaining lessthan 0.2V at the PGOOD output.

VRR

VOVPA

B= +

×1 0 8.

MAX5067

RF

RIN

OVPIN

DIFF

EAN

EAOUT

RB

RAVOUT

Figure 7. OVP Input Delay

+2.0V

PHASE-FAILURE DETECTIONCLP2

CLP1

VREF

DIFF

PGOOD8% OF VREF

10% OF VREF

Figure 8. Power-Good Generator (MAX5067)

(8)

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22 ______________________________________________________________________________________

CLKIN

CLKOUTSGNDPGND

IN

PHASE

DL2

LX2

DH2

DL1

LX1

DH1

VCC

VIN

EAOUT

EANDIFF

SENSE-

SENSE+

CSP2

CSN2

CSP1CSN1

VCC

VIN

VIN

CLKOUTSGNDPGND

IN

PHASE

DL2

LX2

DH2

DL1

LX1

DH1

EAOUT

EAN

CLKIN

CSP2

CSN2

CSP1CSN1

DIFF

VCC

VIN

VIN

CLKOUTSGNDPGND

IN

PHASE

DL2

LX2

DH2

DL1

LX1

DH1

EAOUT

EAN

CLKIN

CSP2

CSN2

CSP1CSN1

DIFF

VCC

VIN

VIN

TO OTHER MAX5065/MAX5067s

MAX5065/MAX5067

MAX5065/MAX5067

MAX5065/MAX5067

LOAD VOUT = +0.6V (MAX5065)VOUT = +0.8V (MAX5067)

Figure 9. Parallel Configuration of Multiple MAX5065/MAX5067s

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MAX5067(MASTER)

Q4

Q3

D2

Q2D1

VIN

4 x 22µFC8–C11

Q1

VIN

VIN = +12V

VCC

D4

D3

C410.1µF

C120.47µF

C384.7µF

C3–C75 x 22µF

L20.6µH

R21.35mΩ

L10.6µH

R11.35mΩ

DH1

LX1

DL1

BST1

VCC

VDD

DH2

LX2

DL2

BST2CSP2CSN2PGOODPHASECLKOUTSGNDPGNDCLP2CLP1

R11

PGOODVCC

R6

C35

C36

R5

C33

C34

C420.1µF

C1, C22 x 47µF

R132.2Ω

C31

C32

R4

CSP1CSN1SENSE+SENSE-INCLKINPLLCMPOVPOUT

R8

R7

EAOUT

EAN

DIFF

OVPIN

EN

C130.47µF

C14, C15,C44, C452 x 100µF

C16–C25,C57–C602 x 270µF

C26–C30,C37

6 x 10µF LOAD

VOUT = +0.8V TO+3.3V AT 104A

VCC

MAX5067(SLAVE)

Q8

Q7

D6

Q6D5

VINC51–C544 x 22µF

Q5

VIN

D8

D7

C640.1µF

C550.47µF

C654.7µF

C46–C505 x 22µF

L40.6µH

R151.35mΩ

L30.6µH

R141.35mΩ

DH1

LX1

DL1

BST1

VCC

VDD

DH2

LX2

DL2

BST2CSP2CSN2PHASE PGOODSGNDPGNDCLP2CLP1

VCC

R19

C67

C66

R18

C68

C69

C610.1µF

R242.2Ω

C70

C71R17

CSP1CSN1SENSE+SENSE-CLKININPLLCMPEN

R21

R20

EAOUT

EAN

DIFF

OVPIN

OVPOUT

C560.47µF

R12C43

VIN

C391µF

C401µF

RH

RL

RA

RB

C621µF

C630.1µF

R16

R3

Figure 10. Four-Phase Parallel Application Circuit (VIN = +12V, VOUT = +0.8V to +3.3V at 104A)

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24 ______________________________________________________________________________________

Phase-Failure Detector (MAX5067)Output current contributions from the two phases arewithin ±10% of each other. Proper current sharingreduces the necessity to overcompensate the externalcomponents. However, an undetected failure of onephase driver causes the other phase driver to run con-tinuously as it tries to provide the entire current require-ment to the load. Eventually, the stressed operationalphase driver fails.

During normal operating conditions, the voltage levelon CLP_ is within the peak-to-peak voltage levels of thePWM ramp. If one of the phases fails, the control loopraises the CLP_ voltage above its operating range. Todetermine a phase failure, the phase-failure detectioncircuit (Figure 8) monitors the output of the currentamplifiers (CLP1 and CLP2) and compares them to a2.0V reference. If the voltage levels on CLP1 or CLP2are above the reference level for more than 1250 clockcycles, the phase failure circuit forces PGOOD low.

Parallel OperationFor applications requiring large output current, parallelup to three MAX5065/MAX5067s (six phases) to triplethe available output current (see Figures 9 and 10). Theparalleled converters operate at the same switching fre-quency but different phases keep the capacitor rippleRMS currents to a minimum. Three parallel MAX5065/MAX5067 converters deliver up to 180A of output cur-rent. To set the phase shift of the on-board PLL, leavePHASE unconnected for 90° of phase shift (2 paralleledconverters), or connect PHASE to SGND for 60° of phaseshift (3 converters in parallel). Designate one converteras master and the remaining converters as slaves.Connect the master and slave controllers in a daisy-chain configuration as shown in Figure 9. Connect CLK-OUT from the master controller to CLKIN of the firstslaved controller, and CLKOUT from the first slaved con-troller to CLKIN of the second slaved controller. Choosethe appropriate phase shift for minimum ripple currentsat the input and output capacitors. The master controllersenses the output differential voltage through SENSE+and SENSE- and generates the DIFF voltage. Disable thevoltage sensing of the slaved controllers by leaving DIFFunconnected (floating). Figure 10 shows a detailed typi-cal parallel application circuit using two MAX5067s. Thiscircuit provides four phases at an input voltage of +12Vand an output voltage range of +0.6V to +3.3V(MAX5065) and +0.8V to +3.3V (MAX5067) at 104A.

Applications InformationEach MAX5065/MAX5067 circuit drives two 180° out-of-phase channels. Parallel two or three MAX5065/MAX5067 circuits to achieve four- or six-phase opera-

tion, respectively. Figure 1 shows the typical applicationcircuit for a two-phase operation. The design criteria fora two-phase converter includes frequency selection,inductor value, input/output capacitance, switchingMOSFETs, sense resistors, and the compensation net-work. Follow the same procedure for the four- and six-phase converter design, except for the input and outputcapacitance. The input and output capacitance require-ments vary depending on the operating duty cycle.

The examples discussed in this data sheet pertain to atypical application with the following specifications:

VIN = +12V

VOUT = +1.8V

IOUT(MAX) = 52A

fSW = 250kHz

Peak-to-Peak Inductor Current (∆IL) = 10A

Table 1 shows a list of recommended external compo-nents (Figure 1) and Table 2 provides component sup-plier information.

Number of PhasesSelecting the number of phases for a voltage regulatordepends mainly on the ratio of input-to-output voltage(operating duty cycle). Optimum output-ripple cancella-tion depends on the right combination of operating dutycycle and the number of phases. Use the followingequation as a starting point to choose the number ofphases:

NPH ≈ K/D (9)

where K = 1, 2, or 3 and the duty cycle is D = VOUT/VIN.

Choose K to make NPH an integer number. For exam-ple, converting VIN = +12V to VOUT = +1.8V yields better ripple cancellation in the six-phase converterthan in the four-phase converter. Ensure that the outputload justifies the greater number of components formultiphase conversion. Generally limiting the maximumoutput current to 25A per phase yields the most cost-effective solution. The maximum ripple cancellationoccurs when NPH = K/D.

Single-phase conversion requires greater size and powerdissipation for external components such as the switch-ing MOSFETs and the inductor. Multiphase conversioneliminates the heatsink by distributing the power dissipa-tion in the external components. The multiple phasesoperating at given phase shifts effectively increase theswitching frequency seen by the input/output capacitors,thereby reducing the input/output capacitance require-ment for the same ripple performance. The lower induc-tance value improves the large-signal response of theconverter during a transient load at the output. Consider

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Table 1. Component List

DESIGNATION QTY DESCRIPTION

C1, C2 2 47µF,16V X5R input-filter capacitors TDK C5750X5R1C476M

C3–C11 9 22µF, 16V input-filter capacitors TDK C4532X5R1C226M

C12, C13 2 0.47µF, 16V capacitors TDK C1608X5R1A474K

C14, C15 2 100µF, 6.3V, output-filter capacitors Murata GRM44-1X5R107K6.3

C16–C25 10 270µF, 2V output-filter capacitors Panasonic EEFUE0D271R

C26–C30, C37 6 10µF, 6.3V output-filter capacitors TDK C2012X5R05106M

C31 1 4700pF, 16V X7R capacitor Vishay-Siliconix VJ0603Y471JXJ

C32, C34, C36 3 470pF, 16V capacitors Murata GRM1885C1H471JAB01

C33, C35, C43 3 0.01µF, 50V X7R capacitors Murata GRM188R71H103KA01

C38 1 4.7µF, 16V X5R capacitor Murata GRM40-034X5R475k6.3

C39 1 0.1µF, 10V Y5V capacitor Murata GRM188F51A105

C40, C41, C42 3 0.1µF, 16V X7R capacitors Murata GRM188R71C104KA01

C44 1 100pF—OVPIN capacitor

D1, D2 2 Schottky diodes ON-Semiconductor MBRS340T3

D3, D4 2 Schottky diodes ON-Semiconductor MBR0520LT1

L1, L2 2 0.6µH, 27A inductors Panasonic ETQP1H0R6BFX

Q1, Q3 2 Upper-power MOSFETs Vishay-Siliconix Si7860DP

Q2, Q4 2 Lower-power MOSFETs Vishay-Siliconix Si7886DP

R1, R2 4 Current-sense resistors, use two 2.7mΩ resistors in parallel, Panasonic ERJM1WSF2M7U

R3, R13 2 2.2Ω ±1% resistors

R4 2 7.5kΩ ±1% resistor

R5, R6 2 1kΩ ±1% resistors

RIN 1 4.99kΩ ±1% resistor

Rf 1 37.4kΩ ±1% resistor

R11 1 10kΩ ±1% resistor

R12 1 10kΩ ±1% resistor

RA 1 See the Overvoltage Protection (MAX5067) section

RB 1 See the Overvoltage Protection (MAX5067) section

RH 1 See the Adaptive Voltage Positioning and Voltage-Error Amplifier sections

RL 1 See the Adaptive Voltage Positioning and Voltage-Error Amplifier sections

RX 1 Open circuit

Table 2. Component SuppliersSUPPLIER PHONE FAX WEBSITE

Murata 770-436-1300 770-436-3030 www.murata.com

ON Semiconductor 602-244-6600 602-244-3345 www.on-semi.com

Panasonic 714-373-7939 714-373-7183 www.panasonic.com

TDK 847-803-6100 847-390-4405 www.tcs.tdk.com

Vishay-Siliconix 1-800-551-6933 619-474-8920 www.vishay.com

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26 ______________________________________________________________________________________

all these issues when determining the number of phasesnecessary for the voltage regulator application.

Inductor SelectionThe switching frequency per phase, peak-to-peak rip-ple current in each phase, and allowable ripple at theoutput determine the inductance value.

Selecting higher switching frequencies reduces theinductance requirement, but at the cost of lower efficien-cy. The charge/discharge cycle of the gate and draincapacitances in the switching MOSFETs create switchinglosses. The situation worsens at higher input voltages,since switching losses are proportional to the square ofinput voltage. Use 500kHz per phase for VIN = +5V and250kHz or less per phase for VIN > +12V.

Although lower switching frequencies per phase increasethe peak-to-peak inductor ripple current (∆IL), the ripplecancellation in the multiphase topology reduces the inputand output capacitor RMS ripple current.

Use the following equation to determine the minimuminductance value:

Choose ∆IL equal to about 40% of the output currentper phase. Since ∆IL affects the output-ripple voltage,the inductance value may need minor adjustment afterchoosing the output capacitors for full-rated efficiency.

Choose inductors from the standard high-current, surface-mount inductor series available from variousmanufacturers. Particular applications may require cus-tom-made inductors. Use high-frequency core materialfor custom inductors. High ∆IL causes large peak-to-peakflux excursion increasing the core losses at higher fre-quencies. The high-frequency operation coupled withhigh ∆IL, reduces the required minimum inductanceand even makes the use of planar inductors possible.The advantages of using planar magnetics include low-profile design, excellent current-sharing between phas-es due to the tight control of parasitics, and low cost.

For example, calculate the minimum inductance atVIN(MAX) = +13.2V, VOUT = +1.8V, ∆IL = 10A, and fSW =250kHz:

The average-current-mode control feature of the

MAX5065/MAX5067 limits the maximum peak inductorcurrent and prevents the inductor from saturating.Choose an inductor with a saturating current greaterthan the worst-case peak inductor current. Use the fol-lowing equation to determine the worst-case inductorcurrent for each phase:

where RSENSE is the sense resistor in each phase.

Switching MOSFETsWhen choosing a MOSFET for voltage regulators,consider the total gate charge, RDS(ON), power dissipa-tion, and package thermal impedance. The product ofthe MOSFET gate charge and on-resistance is a figure ofmerit, with a lower number signifying better performance.Choose MOSFETs optimized for high-frequency switch-ing applications.

The average gate-drive current from the MAX5065/MAX5067 output is proportional to the total capacitance itdrives from DH1, DH2, DL1, and DL2. The power dissi-pated in the MAX5065/MAX5067 is proportional to theinput voltage and the average drive current. See the VIN,VCC, VDD section to determine the maximum total gatecharge allowed from all the driver outputs combined.

The gate charge and drain capacitance (CV2) loss, thecross-conduction loss in the upper MOSFET due tofinite rise/fall time, and the I2R loss due to RMS currentin the MOSFET RDS(ON) account for the total losses inthe MOSFET. Estimate the power loss (PDMOS_) in thehigh-side and low-side MOSFETs using the followingequations:

where QG, RDS(ON), tR, and tF are the upper-switchingMOSFET’s total gate charge, on-resistance at +25°C,rise time, and fall time, respectively.

where D = VOUT/VIN, IDC = (IOUT - ∆IL)/2 and IPK = (IOUT + ∆IL)/2

I I I I ID

RMS HI DC PK DC PK− = + + ×( ) ×2 23

PD Q V f

V I t t fR I

MOS HI G DD SW

IN OUT R F SWDS ON RMS HI

= × ×( ) +

× × +( ) ×

+ ×

41 4 2. ( )

IV

RI

L PEAKSENSE

L_

.= +0 0512

Lk

HMIN =−( ) ×

× ×= µ

13 2 1 8 1 8

13 2 250 100 6

. . .

..

LV V V

V f IMININMAX OUT OUT

IN SW L=

−( ) ×× × ∆

(10)

(11)

(12)

(13)

(14)

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where COSS is the MOSFET drain-to-source capacitance.

For example, from the typical specifications in theApplications Information section with VOUT = +1.8V, thehigh-side and low-side MOSFET RMS currents are 9.9Aand 24.1A, respectively. Ensure that the thermal imped-ance of the MOSFET package keeps the junction tem-perature at least 25°C below the absolute maximumrating. Use the following equation to calculate maxi-mum junction temperature:

TJ = PDMOS x θJ-A + TA

Input CapacitorsThe discontinuous input-current waveform of the buckconverter causes large ripple currents in the inputcapacitor. The switching frequency, peak inductor cur-rent, and the allowable peak-to-peak voltage ripplereflected back to the source dictate the capacitancerequirement. Increasing the number of phases increas-es the effective switching frequency and lowers thepeak-to-average current ratio, yielding a lower inputcapacitance requirement.

The input ripple is comprised of ∆VQ (caused by thecapacitor discharge) and ∆VESR (caused by the ESR ofthe capacitor). Use low-ESR ceramic capacitors withhigh-ripple-current capability at the input. Assume thecontributions from the ESR and capacitor discharge areequal to 30% and 70%, respectively. Calculate theinput capacitance and ESR required for a specified rip-ple using the following equation:

where IOUT is the total output current of the multiphaseconverter and N is the number of phases.

For example, at VOUT = +1.8V, the ESR and inputcapacitance are calculated for the input peak-to-peakripple of 100mV or less yielding an ESR and capaci-tance value of 1mΩ and 200µF.

Output CapacitorsThe worst-case peak-to-peak and capacitor RMS ripplecurrent, the allowable peak-to-peak output ripple volt-age, and the maximum deviation of the output voltageduring step loads determine the capacitance and theESR requirements for the output capacitors.

In multiphase converter design, the ripple currents fromthe individual phases cancel each other and lower theripple current. The degree of ripple cancellationdepends on the operating duty cycle and the number ofphases. Choose the right equation from Table 3 to calcu-late the peak-to-peak output ripple (∆IP-P) for a givenduty cycle of two-, four-, and six-phase converters. Themaximum ripple cancellation occurs when NPH = K / D.

C

IN

D D

V fIN

OUT

Q SW=

× −( )×

1

ESRV

IN

IINESR

OUT L=

( )+

∆∆2

I I I I ID

RMS LO DC PK DC PK− = + + ×( ) ×−( )2 2 1

3

PD Q V f

C V fR I

MOS LO G DD SW

OSS IN SWDS ON RMS LO

= × ×( ) +

× × ×

+ ×

23

1 42

2. ( )

Table 3. Peak-to-Peak Output RippleCurrent Calculations

NUMBER OFPHASES (N)

DUTYCYCLE (D)

EQUATION FOR ∆IP-P

2 < 50%

2 > 50%

4 0 to 25%

4 25% to 50%

4 > 50%

6 < 17%

∆IV D

L fO

SW= −

×( )1 2

∆IV V D

L fIN O

SW=

−( ) −( )×

2 1

∆IV D

L fO

SW= −

×( )1 4

∆IV D D

D L fO

SW= − −

× × ×( )( )1 2 4 1

2

∆IV D D

D L fO

SW= − −

× ×( )( )2 1 3 4

∆IV D

L fO

SW= −

×( )1 6

(15)

(16)

(17) (18)

(19)

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The allowable deviation of the output voltage during thefast transient load dictates the output capacitance andESR. The output capacitors supply the load step untilthe controller responds with a greater duty cycle. Theresponse time (tRESPONSE) depends on the closed-loopbandwidth of the converter. The resistive drop acrossthe capacitor ESR and capacitor discharge causes avoltage drop during a step load. Use a combination ofSP polymer and ceramic capacitors for better transientload and ripple/noise performance.

Keep the maximum output voltage deviation less thanor equal to the adaptive voltage-positioning window(∆VOUT). Assume 50% contribution each from the out-put capacitance discharge and the ESR drop. Use thefollowing equations to calculate the required ESR andcapacitance value:

where ISTEP is the load step and tRESPONSE is theresponse time of the controller. Controller responsetime depends on the control-loop bandwidth.

Current LimitThe average-current-mode control technique of theMAX5065/MAX5067 accurately limits the maximum out-put current per phase. The MAX5065/MAX5067 sensethe voltage across the sense resistor and limit the peakinductor current (IL-PK) accordingly. The ON cycle ter-minates when the current-sense voltage reaches 45mV(min). Use the following equation to calculate maximumcurrent-sense resistor value:

where PDR is the power dissipation in sense resistors.Select 5% lower value of RSENSE to compensate for anyparasitics associated with the PC board. Also, select anon inductive resistor with the appropriate wattage rating.

Reverse Current LimitThe MAX5065/MAX5067 limit the reverse current whenVBUS is higher than the preset output voltage.

Calculate the maximum reverse current based on VCLR,the reverse-current-limit threshold, and the current-senseresistor.

where IREVERSE is the total reverse current into the con-verter.

CompensationThe main control loop consists of an inner current loopand an outer voltage loop. The MAX5065/MAX5067 usean average-current-mode control scheme to regulatethe output voltage (Figure 4). IPHASE1 and IPHASE2 arethe inner average current loops. The VEA output pro-vides the controlling voltage for these current sources.The inner current loop absorbs the inductor pole reduc-ing the order of the outer voltage loop to that of a sin-gle-pole system.

A resistive feedback around the VEA provides the bestpossible response, since there are no capacitors tocharge and discharge during large-signal excursions, RFand RIN determine the VEA gain. Use the following equa-tion to calculate the value for RF:

where GC is the current-loop transconductance and Nis number of phases.

When designing the current-control loop ensure that theinductor downslope (when it becomes an upslope at theCEA output) does not exceed the ramp slope. This is anecessary condition to avoid sub-harmonic oscillationssimilar to those in peak current-mode control with insuffi-cient slope compensation. Use the following equation tocalculate the resistor RCF:

For example, the maximum RCF is 12kΩ for RSENSE =1.35mΩ.

CCF provides a low-frequency pole while RCF provides amidband zero. Place a zero at fZ to obtain a phase bumpat the crossover frequency. Place a high-frequency pole

Rf L

V RCFSW

OUT SENSE≤ × × ×

×2 102

GRC

S= 0 05.

RI R

N G VFOUT IN

C OUT=

×× × ∆

IV

RREVERSECLR

SENSE= ×2

PDRR

SENSE= × −2 5 10 3.

RI

N

SENSEOUT

= 0 045.

CI t

VOUT

STEP RESPONSE

Q=

×∆

ESRV

IOUTESR

STEP= ∆ (20)

(21)

(22)

(23)

(25)

(26)

(27)

(24)

MA

X5

06

5/M

AX

50

67

Dual-Phase, +0.6V to +3.3V Output Parallelable,Average-Current-Mode Controllers

______________________________________________________________________________________ 29

(fP) at least a decade away from the crossover frequencyto achieve maximum phase margin.

Use the following equations to calculate CCF and CCFF:

PC Board LayoutUse the following guidelines to layout the switchingvoltage regulator:

1) Place the VIN and VCC bypass capacitors close tothe MAX5065/MAX5067.

2) Minimize the area and length of the high-currentloops from the input capacitor, upper switchingMOSFET, inductor, and output capacitor back tothe input capacitor negative terminal.

3) Keep short the current loop from the lower-switch-ing MOSFET, inductor, and output capacitor.

4) Place the Schottky diodes close to the lowerMOSFETs and on the same side of the PC board.

5) Keep the SGND and PGND isolated and connectthem at one single point close to the negative termi-nal of the input-filter capacitor.

6) Run the current-sense lines CS+ and CS- veryclose to each other to minimize the loop area.Similarly, run the remote-voltage sense linesSENSE+ and SENSE- close to each other. Do notcross these critical signal lines through power cir-cuitry. Sense the current right at the pads of thecurrent-sense resistors.

7) Avoid long traces between the VCC bypass capaci-tors, driver output of the MAX5065/MAX5067, MOSFET gates and PGND pin. Minimize the loopformed by the VCC bypass capacitors, bootstrapdiode, bootstrap capacitor, MAX5065/MAX5067,and upper MOSFET gate.

8) Place the bank of output capacitors close to the load.

9) Distribute the power components evenly across theboard for proper heat dissipation.

10) Provide enough copper area at and around theswitching MOSFETs, inductor, and sense resistorsto aid in thermal dissipation.

11) Use at least 4oz copper to keep the trace induc-tance and resistance to a minimum. Thin copper PCboards can compromise efficiency since high cur-rents are involved in the application. Also, thickercopper conducts heat more effectively, therebyreducing thermal impedance.

Chip InformationTRANSISTOR COUNT: 5451

PROCESS: BiCMOS

Cf RCFFP CF

=× × ×

12 π

Cf RCFZ CF

=× × ×

12 π

(28)

(29)

Selector Guide

PART OUTPUT

MAX5065 Adjustable +0.6V to +3.3V

MAX5067Adjustable +0.8V to +3.3V with OVP, PGOOD,Phase Failure Detector

MA

X5

06

5/M

AX

50

67

Dual-Phase, +0.6V to +3.3V Output Parallelable,Average-Current-Mode Controllers

Pin Configurations

28 SSOP

TOP VIEW

MAX5065

1

2

3

CSP2

CSN2

PHASE

4

VCC

5

6

7

CLP2

SGND

CLP1

28

27

26

CLKIN

CLKOUT

BST2

25 DH2

24

23

22

LX2

DL2

PGND

8

9

10

SENSE+

SENSE-

DIFF

11EAN

12

13

14

EAOUT

CSP1

CSN1

21

20

19

IN

DL1

18 LX1

17

16

15

DH1

BST1

EN

PLLCMPN.C.

N.C.

SGND

OVPIN

N.C.

CLP1

OVPOUT

EAN

N.C.

EAOU

TDH1*

PGOOD

VCC

SENSE+

SENSE-

*CONNECT THE THIN QFN EXPOSED PAD TO SGND GROUND PLANE.

BST1

LX1

VDD

DL1

PGND

LX2

DL2

IN

DH2

N.C.

CLP2

BST2

N.C.

DIFF

N.C.1

2

3

4

5

6

7

8

9

10

11

14 15 16 17 18 19 20 21 2212 13

CSP1

CSN1 N.C. EN

SGND N.C.

33

32

31

30

29

28

27

26

25

24

23

44 43 42 41 40 39 38 37 36 35 34

PLLC

MP

CSP2

CLKO

UT

PHAS

E

CSN2

CLKI

N

N.C.

SGND

44 THIN QFN*

MAX5067

30 _____________________________________________________________________________________

MA

X5

06

5/M

AX

50

67

Dual-Phase, +0.6V to +3.3V Output Parallelable,Average-Current-Mode Controllers

______________________________________________________________________________________ 31

SS

OP

.EP

S

PACKAGE OUTLINE, SSOP, 5.3 MM

11

21-0056 CREV.DOCUMENT CONTROL NO.APPROVAL

PROPRIETARY INFORMATION

TITLE:

NOTES:1. D&E DO NOT INCLUDE MOLD FLASH.2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .15 MM (.006").3. CONTROLLING DIMENSION: MILLIMETERS.4. MEETS JEDEC MO150.5. LEADS TO BE COPLANAR WITHIN 0.10 MM.

7.90H

L

0∞

0.301

0.025

8∞

0.311

0.037

0∞

7.65

0.63

8∞

0.95

MAX

5.38

MILLIMETERS

B

C

D

E

e

A1

DIM

A

SEE VARIATIONS

0.0256 BSC

0.010

0.004

0.205

0.002

0.015

0.008

0.212

0.008

INCHES

MIN MAX

0.078

0.65 BSC

0.25

0.09

5.20

0.05

0.38

0.20

0.21

MIN

1.73 1.99

MILLIMETERS

6.07

6.07

10.07

8.07

7.07

INCHES

D

D

D

D

D

0.239

0.239

0.397

0.317

0.278

MIN

0.249

0.249

0.407

0.328

0.289

MAX MIN

6.33

6.33

10.33

8.33

7.33

14L

16L

28L

24L

20L

MAX N

A

D

e A1 L

C

HE

N

12

B

0.068

Package Information(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,go to www.maxim-ic.com/packages.

Package Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,go to www.maxim-ic.com/packages.)

32, 4

4, 4

8L Q

FN.E

PS

PROPRIETARY INFORMATION

APPROVAL

TITLE:

DOCUMENT CONTROL NO.

21-0144

PACKAGE OUTLINE32, 44, 48L THIN QFN, 7x7x0.8 mm

1C

REV.

2

e

L

e

L

A1A

A2

E/2

E

D/2

D

DETAIL A

D2/2

D2

b

L

k

E2/2

E2(NE-1) X e

(ND-1) X e

e

CLCL

CL

CL

k

DALLASSEMICONDUCTOR

PROPRIETARY INFORMATION

DOCUMENT CONTROL NO.APPROVAL

TITLE:

CREV.

22

21-0144

PACKAGE OUTLINE32, 44, 48L THIN QFN, 7x7x0.8 mm

DALLASSEMICONDUCTOR

MA

X5

06

5/M

AX

50

67

Dual-Phase, +0.6V to +3.3V Output Parallelable,Average-Current-Mode Controllers

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses areimplied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

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