max12900 ultra-low-power 4-20a sensor transitter package: 5mm x 5mm x 0.8mm 32-pin tqfn applications...

General DescriptionThe MAX12900 is an ultra-low-power, highly integrated 4-20mA sensor transmitter. The MAX12900 integrates ten building blocks in a small package: a wide input supply voltage LDO, two conditioner circuits for pulse-width-modulated (PWM) inputs, two low-power, low-drift, general-purpose operational amplifiers (op amp) one wide bandwidth, zero-offset drift operational amplifier; two diagnostic comparators, a power-up sequencer with power good output to allow for a smooth power-up, and a low-drift voltage reference.The MAX12900 converts PWM data from a microcontroller into current over a 4-20mA loop with two, three, or four-wire configurations.The equivalent to an ultra-low-power, high-resolution, digital-to-analog converter is realized with the combination of two-PWM signals received from a microcontroller, the two conditioner circuits, and an active filter built with the integrated low-power op amp. The outputs of the two conditioner circuits provide a stable PWM amplitude over voltage supply and temperature variation. The wide band-width amplifier, in combination with a discrete transistor, converts a voltage input into a current output and allows HART and Foundation Fieldbus H1 signal modulation. The zero-offset operational amplifier and the low-drift voltage reference provide negligible error over wide temperature. The low-power operational amplifier and comparators provide building blocks for enhanced diagnostic features. Supply rail monitoring, output current readback, open circuit and failure detection are a few examples of diagnostic features. All these features, as well as ultra-low-power and high accuracy make the MAX12900 ideal for loop-powered smart sensor transmitters for industrial application.The MAX12900 is available in 5mm x 5mm 32-pin TQFN package and operates over a wide industrial temperature range of -40°C to +125°C.

Benefits and Features Wide Input Supply Range: 4.0V to 36V Ultra-Low-Power Consumption: 170µA (typ) High Linearity: 0.01% (Max Error) High Resolution: Up to 16 Bit Low Drift Voltage Reference: 10ppm/°C max Wide Temperature Range: -40°C to +125°C Small Package: 5mm x 5mm x 0.8mm 32-pin TQFN

Applications Loop-Powered 4-20mA Current Transmitter Smart Sensors Remote Instrumentation Industrial Automation and Process Control

Ordering Information appears at end of data sheet.

19-100086; Rev 2; 3/18

MAX12900 Ultra-Low-Power 4-20mA Sensor Transmitter

EVALUATION KIT AVAILABLE

MAX12900

POWER-UP SEQUENCER

VCCID PWRGOOD

REFGND

VCCILDOFB

1.2V VREF

VCC

COMP2NCOMP2O

COMP2P

COMP1N

COMP1PCOMP1O

VCCI VDD

LDO

OP3

PWMBOPWMBP

VCCI REFBUF1V

PWMAO

PWMAP

VCCI1V

SHDN

SHDN

2.5V VREF

VCCI

VCCI VDD

VCCI VDD

VCCI

REFO

REFBUF

OP1OP1P

OP1NOP1O

VCCI

OP3P

OP3NOP3O

VCCI

OP2

VCCI

OP2P

OP2NOP2O

EP

COMPARATORS

OP-AMPS

PWM

VREF

MAX12900 INTEGRATES 10 BUILDING BLOCKS:LDOPOWER-UP SEQUENCERTWO COMPARATORS (COMP1, COMP2)TWO GENERAL PURPOSE OP AMPS (OP1, OP2)ONE LOW DRIFT OP AMP (OP3)2.5V PRECISION REFERENCETWO PWM RECEIVERS (PWMA, PWMB)


www.maximintegrated.com Maxim Integrated 2

Functional Block Diagram

VCC to GND ..........................................................-0.3V to +40VVCC to VCCI .........................................................-0.3V to +40VVCCI and VCCID to GND .......................................-0.3V to +6VVCCI to VCCID .....................................................-0.3V to +0.3VVDD to GND ............................................................-0.3V to +6VPWRGOOD to GND .................................. -0.3V to VCCI + 0.3VLDOFB to GND ......................................... -0.3V to VCCI + 0.3VI/C and REFGND to GND ...................................-0.3V to + 0.3VSHDN to GND ........................................... -0.3V to VCCI + 0.3VREFO to GND ........................................... -0.3V to VCCI + 0.3V

Op AmpsOP1O, OP2O, OP3O to GND ................... -0.3V to VCCI + 0.3VOP1P, OP1N, OP2P, OP2N, OP3P,

OP3N to GND ......................-0.3V to min [4.5V, VCCI + 0.3V]Current into OP1P, OP1N, OP2P, OP2N,

OP3P, OP3N .................................................................±20mACurrent into OP3O............................................................±30mAOutput Short-Circuit Duration for OP1 and

OP2 to VCCI or GND ............................................Continuous

ComparatorsCOMP1P, COMP1N, COMP2P, COMP2N

to GND ................................................... -0.3V to VCCI + 0.3VCOMP1O, COMP2O to GND ..................... -0.3V to VDD + 0.3VCurrent into COMP1P, COMP1N,

COMP2P, COMP2N .....................................................±20mAOutput Short-Circuit Duration to

VDD or GND ..........................................................ContinuousPWM ConditionersPWMAP, PWMBP to GND ......................... -0.3V to VCCI + 0.3VPWMAO, PWMBO to GND ....................... -0.3V to VCCI + 0.3VCurrent into PWMAP, PWMBP .........................................±20mAOutput Short-Circuit Duration to VCCI or GND .........Continuous

Continuous Power Dissipation (TA = +70°C, derate 35.7mW/°C above +70°C) ...........................2857.1mW

Operating Temperature Range ......................... -40°C to +125°CFunctional Temperature Range

(Startup condition) ........................................ -55°C to +125°CMaximum Junction Temperature .....................................+150°CStorage Temperature Range ............................ -65°C to +150°CSoldering Temperature (reflow) .......................................+260°CLead Temperature ...........................................................+300°C

32 TQFNPACKAGE CODE T3255

Outline Number 21-0140Land Pattern Number 90-0015Thermal Resistance, Four-Layer Board:Junction to Ambient (θJA) 40.2°C/WJunction to Case (θJC) 2.0°C/W



Absolute Maximum Ratings

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

For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.

Package Information

Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.

http://pdfserv.maximintegrated.com/package_dwgs/21-0140.PDF

http://pdfserv.maximintegrated.com/land_patterns/90-0015.PDF

http://www.maximintegrated.com/packages

http://www.maximintegrated.com/thermal-tutorial

VCCI = +3.0V to +5.5V, VGND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C, VCCI = +3.3V. (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITSVOLTAGE REFERENCE 2.5VSTATICSupply Voltage VCCI Guaranteed by line regulation test 3.0 5.5 V

VCCI Line Regulation ∆VREF/∆VCCI

3.0V ≤ VCCI ≤ 5.5V 20 140 µV/V

VCC Line Regulation ∆VREF/∆VCC

4.3V ≤ VCC ≤ 36V, VCCI = 3.3V 1.2 nV/V

Output Voltage VOUT TA = +25°C 2.495 2.500 2.505 V

Output Voltage Temperature Coefficient TCVOUT CREF = 2nF (Note 2) 2 10 ppm/°C

Temperature Hysteresis ∆VREF/Cycle CREF = 2nF -140 ppm

Load Regulation ∆VREF/∆IOUT

Sourcing 0V ≤ IOUT ≤ 500 µA 0.14 0.6 µV/µA

Short-Circuit Current ISC Short to GND 3 mA

Maximum Capacitive Load CREF 2 nF

DYNAMIC

VCCI Ripple Rejection VREF/VCCI

VCCI = 3.3V, f = 120Hz 90 dB

VCC Ripple Rejection VREF/VCC

VCC = 12V, VCCI = 3.3V, f = 120Hz 160 dB

Turn-On Settling Time tRFrom 90% of VCCI to within 0.1% of VREF, CREF = 2nF 85 µs

Noise Voltage eREF0.1Hz to 10Hz 40 µVp-p10Hz to 10kHz 125 µVRMS



Electrical CharacteristicsVoltage Reference

VCCI = +3.0V to +5.5V, VGND = 0V, outputs connected to 100kΩ in parallel with 10pF terminated to VREF/2, input pulses have 10ns rise and fall times, PWM period = 100µs, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C, VCCI = +3.3V. (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITSPWMA, PWMBSTATICSupply Voltage VCCI Guaranteed by PSRRVOH test 3.0 5.5 V

VCCI Supply Rejection Ratio of Input Threshold Voltage

PSRRVTH 3.0V ≤ VCCI ≤ 5.5V 65 dB

VCC Supply Rejection Ratio of Input Threshold Voltage

4.3V ≤ VCC ≤ 36V, VCCI = 3.3V 150 dB

VCCI Supply Rejection Ratio of Output Voltage High

PSRRVOH 3.0V ≤ VCCI ≤ 5.5V, no load 59 75 dB

VCC Supply Rejection Ratio of Output Voltage High

4.3V ≤ VCC ≤ 36V, VCCI = 3.3V, no load 160 dB

Input Voltage Range 0 VCCI VInput Voltage High VIH PWMAP, PWMBP, SHDN 1.4 VInput Voltage Low VIL PWMAP, PWMBP, SHDN 0.6 V

PWMAP, PWMBP Input Threshold VTH 1.0 V

PWMAP, PWMBP Input Threshold Accuracy 1 mV

PWMAP, PWMBP Hysteresis PWMHYS 5 mV

SHDN Hysteresis SHDNHYS 50 mVInput Bias Current IB VPWMAP = VPWMBP = 0V -1 nAInput Capacitance CIN 2 pFOutput Voltage High VOH VREF - VOUT, ISOURCE = 100 µA 0.1 VOutput Voltage Low VOL VOUT – VGND, ISINK = 100 µA 0.1 V

Short Circuit Current ISCPWMAO or PWMBO short to VREF -12 mAPWMAO or PWMBO short to GND 6 mA

Output High Level Voltage Matching

Difference between the voltage of the two PWM outputs -2 +2 mV

Output Low Level Voltage Matching

Difference between the voltage of the two PWM outputs -2 +2 mV

PWMAO, PWMBO Output Voltage High Drift

7 µV/°C

Linearity From code 10 to code 245 (Note 2), Figure 1 0.01 %FSR



Electrical Characteristics (continued)PWM Conditioners

VCCI = +3.0V to +5.5V, VGND = 0V, outputs connected to 100kΩ in parallel with 10pF terminated to VREF/2, input pulses have 10ns rise and fall times, PWM period = 100µs, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C, VCCI = +3.3V. (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITSDYNAMICPropagation Delay Active to Shut down tSHDN

From 50% of SHDN to when PWM outputs are Hi-Z 10 µs

Propagation Delay Shut down to Active tACT

From 50% of SHDN to when PWM outputs are active 10 µs

Minimum Input Pulse Width IPW

Single high state, guaranteed by PWM timing tests 390 ns

Driver Rise Time for PWMAO and PWMBO RTA, RTB

Single 390ns pulse, 10% to 90% 7 ns

Driver Fall Time for PWMAO and PWMBO FTA, FTB 6 ns

PWMAO to PWMBO Rise Time Matching Single 390ns pulse -4 +4 ns

PWMAO to PWMBO Fall Time Matching Single 390ns pulse -2 +2 ns

PWMAO to PWMBO Delay Matching

Single 390ns pulse, measured at 50% FSR of rising edges -30 +30 ns

PWMAO and PWMBO Pulse Width Accuracy

Single 390ns pulse, pulse width difference between input and output waveforms (measured at 50% points)

-30 +30 ns

PWMAO and PWMBO Pulse Width Variation vs. Temperature

Single 390ns pulse 25 ps/°C

PWMAO and PWMBO Pulse Width Matching

Single 390ns pulse, difference between PWMAO and PWMBO pulse widths -30 +30 ns



Electrical Characteristics (continued)PWM Conditioners (continued)

VCCI = +3.0V to +5.5V, VGND = 0V, VCM = VOUT = VCCI/2, no resistive load, CL = 10pF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C, VCCI = +3.3V. (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITSOP1, OP2STATICSupply Voltage VCCI Guaranteed by PSRRVCCI test 3.0 5.5 V

VCCI Supply Rejection Ratio PSRRVCCI 3.0V ≤ VCCI ≤ 5.5V 62 80 dB

VCC Supply Rejection Ratio PSRRVCC 4.3V ≤ VCC ≤ 36V, VCCI = 3.3V 165 dB

Common Mode Input Voltage

VCMR

Guaranteed by CMRR testVCCI ≤ 4.5V -0.1 VCCI -

0.5 V

Guaranteed by CMRR test4.5V ≤ VCCI ≤ 5.5V -0.1 +4.0 V

Common Mode Rejection Ratio CMRR -0.1V ≤ VCM ≤ min (4.0V, VCCI - 0.5V) 56 dB

Input Offset Voltage VOS 1 mV

Input Offset Voltage Drift ∆VOS (Note 2) 15 µV/°C

Input Bias Current IB-40°C ≤ TA ≤ +85°C (Note 2) -15 +15 pA

-40°C ≤ TA ≤ +125°C (Note 2) -125 +125 pA

Input Offset Current IOS-40°C ≤ TA ≤ +85°C (Note 2) -15 +15 pA

-40°C ≤ TA ≤ +125°C (Note 2) -80 +80 pA

Open-Loop Gain AVOL

150mV ≤ VOUT ≤ VCCI - 150mV, RL = 100kΩ connected to VCCI / 2, -40°C ≤ TA ≤ +85°C

78 dB

-40°C ≤ TA ≤ +125°C 72

Output Voltage High VOHVCCI – VOUT,RL = 100kΩ connected to VCCI / 2

25 mV

Output Voltage Low VOLVOUT - VGND, RL = 100kΩ connected to VCCI / 2

25 mV

Output Short-Circuit Current IOUT(SC) ±3 mA



Electrical Characteristics (continued)Op Amps


PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITSDYNAMICInput Voltage Noise Density eN f = 1kHz 150 nV/√Hz

Input Current Noise Density iN f = 1kHz 40 fA/√Hz

Gain Bandwith Product GBWP 200 kHzSlew Rate SR 0.1 V/ µsSettling Time To 0.1%, VOUT = 2V step, AV = -1V/V 25 µs

Maximum Capacitive Load CL No sustained oscillations, AV = 1V/V 100 pF

OP3 (RL = 100kΩ CONNECTED to VCCI/2, CL = 20pF)STATICSupply Voltage VCCI Guaranteed by PSRRVCCI test 3.0 5.5 V

VCCI Supply Rejection Ratio PSRRVCCI 3.0V ≤ VCCI ≤ 5.5V 107 dB


Common Mode Input Voltage VCMR

Guaranteed by CMRR test VCCI ≤ 4.3V -0.1 VCCI -

0.3 V

Guaranteed by CMRR test 4.3V ˂ VCCI ≤ 5.5V -0.1 +4.0 V

Common Mode Rejection Ratio CMRR -0.1V ≤ VCM ≤ min(4.0V, VCCI - 0.3V) 105 dB

Input Offset Voltage VOS TA = 25°C, VCCI = 3.3V (Note 2) -10 +10 µV

Input Offset Voltage Drift ∆VOS (Note 2) 5 70 nV/°C

Input Bias Current IB-40°C ≤ TA ≤ +85°C (Note 2) -15 +15 pA

-40°C ≤ TA ≤ +125°C (Note 2) -125 +125 pAInput Offset Current IOS -40 pA

Input Capacitance CIN 2 pF

Open-Loop Gain AVOL 150mV ≤ VOUT ≤ VCCI-150mV, RL = 5kΩ connected to VCCI / 2

123 150 dB

Output Voltage High VOHVCCI – VOUT,RL = 100kΩ connected to VCCI / 2

12 mV

Output Voltage Low VOLVOUT - VGND, RL = 100kΩ connected to VCCI / 2

12 mV



Electrical Characteristics (continued)Op Amps (continued)


VCCI = +3.0V to +5.5V, VDD = +1.8V to +3.6V, VGND = 0V, VCM = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C, VDD = VCCI = +3.3V. (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITSDYNAMICInput Voltage Noise Density eN f = 1kHz 35 nV/√Hz

Input Voltage Noise 0.1Hz ≤ f ≤ 10Hz 0.7 µVp-p

Input Current Noise Density iN f = 1kHz 80 fA/√Hz

Gain Bandwidth Product GBWP 2.2 MHz

Slew Rate SR 0.7 V/µsPhase Margin 57 °

Maximum Capacitive Load CL No sustained oscillations, AV = 1V/V 300 pF

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITSCOMP1, COMP2STATICSupply Voltage VCCI Guaranteed by PSRRVCCI test 3.0 5.5 V

Supply Voltage Output Stage VDD 1.8 3.6 V

VCCI Supply Rejection Ratio PSRRVCCI 3.0V ≤ VCCI ≤ 5.5V 54 dB


Common Mode Input Voltage

VCMR Guaranteed by CMRR test 0 VCCI - 1.3 V

Common Mode Rejection Ratio CMRR 0V ≤ VCM ≤ VCCI – 1.3V 56 75 dB

Input Offset Voltage VOS -10 +10 mVHysteresis VHYS 15 mVInput Bias Current IB VCM = 0V -10 -1 nAInput Offset Current IOS 1 nAInput Capacitance CIN 2 pFOutput Voltage High VOH VDD - VOUT, ISOURCE = 100 µA 0.4 V



Electrical Characteristics (continued)

Electrical Characteristics (continued)

Op Amps (continued)

Comparators

VCCI = +3.0V to +5.5V, VDD = +1.8V to +3.6V, VGND = 0V, VCM = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C, VDD = VCCI = +3.3V. (Note 1)

VCC = +4.0V to +36V, VGND = 0V, CLOAD = 0.32µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C, VCC = +24V. (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITSOutput Voltage Low VOL VOUT – VGND, ISINK = 100 µA 0.4 V

Short Circuit Current ISCShort to GND 2 mAShort to VDD -2 mA

DYNAMICPropagation Delay Low to High tPD+

CLOAD = 10pF, threshold set to VCCI -1.4V, input swings from 0V to VCCI -1.3V 2 µs

Propagation Delay High to Low tPD-

CLOAD = 10pF, threshold set to 0.1V, input swings from VCCI -1.3V to 0V 0.5 µs

Rise Time TR CLOAD= 10pF 50 nsFall Time TF CLOAD= 10pF 50 ns

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITSLDOSTATICSupply Voltage VCC Guaranteed by line regulation test 4.0 24 36 VDropout Voltage Guaranteed by line and load regulation tests 1 V

VCC Line Regulation VCC from VCCI+1V to 36V, ILDO = 4mA, VCCI = 3.0V to 5.5V 2 25 mV

Output Voltage VCCI Guaranteed by block PSRRVCCI tests 3.0 5.5 V

Output Voltage Accuracy

VCC = 24V, no load except for LDOFB resistor divider, VCCI = 3.3V -3.5 +3.5 %

Output Current Range ILDO Guaranteed by load regulation test 0 4 mAVCCI Current Limit ICCI_Limit VCCI short to GND 12 mA

Load Regulation VCC = VCCI+1V, ILDO from 0mA to 4mA,VCCI = 3.0V to 5.5V 1 10 mV

Maximum Capacitive Load CLOAD

No resistive load except for LDOFB resistor divider 5 µF

DYNAMICVCC Supply Rejection Ratio PSRR VCC = 12V, DC to 120Hz 70 dB



Electrical Characteristics (continued)Comparators (continued)

LDO

VCC = +4.0V to +36V, VCCI = +3.0V to +5.5V, VDD = +1.8V to +3.6V, VGND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C, VCC = +24V, VDD = VCCI = +3.3V. (Note 1)

Note 1: Specifications are 100% tested at TA = +25°C (exceptions noted). All temperature limits are guaranteed by design.Note 2: Guaranteed by design, not production tested.

Figure 1. Typical PWM Timing Diagram

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITSSTATIC

VCC Supply Current ICC

VCC = 24V, VCCI = 3.3V, SHDN = 3.3V, no load,-40°C ≤ TA ≤ +85°C 170 250 µA

-40°C ≤ TA ≤ +125°C 265 µA

VCC Supply Current with PWM Conditioners Shutdown

ICC_SHDN VCC = 24V, VCCI = 3.3V, SHDN = 0V, no load 142 µA

VDD Supply Current IDD 1 µA

PWRGOOD Turn-on Threshold 90 % of

VCCI

PWRGOOD Turn-off Threshold 80 % of

VCCI

PWRGOOD Voltage High VOH VCCI – VOUT, ISOURCE = 100 µA 0.4 V

PWRGOOD Voltage Low VOL VOUT – VGND, ISINK = 100 µA 0.4 V

PWRGOOD Short Circuit Current ISC

Short to GND 2 mAShort to VCCI -2 mA

DYNAMICPWRGOOD Turn-on Delay

From VCCI crossing turn-on threshold to PWRGOOD high 0.7 ms

256 STEPS

0.1ms

0.1ms/256 PWMAPPWMBP



Electrical Characteristics (continued)Chip-Level Specifications

VCC = +24V, VDD = VCCID = VCCI = +3.3V, GND = 0V, op amp VCM = VOUT = VCCI/2, op amp CL = 15pF, comparator and PWM CL = 10pF, LDO CLOAD = 0.32µF, no resistive load on any output, TA = +25°C, unless otherwise noted.

1 10 100 1k 10k 100k0

2

4

6

8

10

12

14

16

18

20

LOO

P CU

RREN

T NO

ISE

DENS

ITY

(nA/

√Hz)

FREQUENCY (Hz)

4mA LOOP CURRENT NOISEDENSITY vs. FREQUENCY

OVER 500Ω LOAD toc08

-0.020

-0.015

-0.010

-0.005

0.000

0.005

0.010

0.015

0.020

0 20 40 60 80

LOO

P CU

RREN

T LI

NEAR

ITY

(%FS

)

PWM DUTY CYCLE (%)

16V 24V 32V 36V

4-20mA LINEARITY vs. PWM DUTY CYCLE AND

LOOP VOLTAGEtoc04

VLOOP = 24VRLOAD = 100Ω

0.0

5.0

10.0

15.0

20.0

25.0

30.0

0 10 20 30 40 50 60 70 80 90 100

LOO

P CU

RREN

T (m

A)

DUTY CYCLE (%)

TRANSFER CHARACTERISTICSLOOP CURRENT vs. PWM DUTY CYCLE

toc01


4mA LOOP CURRENT NOISEDURING SILENCEOVER 500Ω LOAD

100ms/div

10mV/div

toc07

VOUTN

VINSIDE

VBACKUP

0.0

5.0

10.0

15.0

20.0

25.0

30.0

0 0.5 1 1.5 2 2.5

LOO

P CU

RREN

T (m

A)

OP3 INPUT (V)

TRANSFER CHARACTERISTICSLOOP CURRENT vs. OP3 INPUT

toc02


-0.020

-0.015

-0.010

-0.005

0.000

0.005

0.010

0.015

0.020

0 20 40 60 80

LOO

PCU

RREN

TLI

NEAR

ITY

(%FS

)

PWM DUTY CYCLE (%)

-40°C 25°C 85°C 125°C

4-20mA LINEARITY vs.PWM DUTY CYCLE

AND TEMPERATUREtoc03


10 100 1k 10k 100k 1M0

10

20

30

40

50

60

70

PSRR

(dB)

FREQUENCY (Hz)

VCC SUPPLY REJECTIONRATIO vs. FREQUENCY

(SYSTEM LEVEL) toc09

0

50

100

150

200

250

300

350

400

-40 -25 -10 5 20 35 50 65 80 95 110 125

VCC

SUPP

LY C

URRE

NT (

µA)

TEMPERATURE (°C)

4mA 12mA 20mA

VCC SUPPLY CURRENT(SYSTEM LEVEL)

vs. TEMPERATUREtoc05

RLOAD = 100Ω

0

50

100

150

200

250

300

350

400

16 21 26 31 36

VCC

SUPP

LY C

URRE

NT (

µA)

VCC VOLTAGE (V)

4mA 12mA 20mA

VCC SUPPLY CURRENTvs. SUPPLY VOLTAGE

toc06

RLOAD = 100Ω

Maxim Integrated 12www.maximintegrated.com


Typical Operating Characteristics


HART COMMUNICATION

2ms/div

200mV/div(AC-COUPLED)

toc13

VOUTN

VINSIDE

VBACKUP

10 100 1k 10k 100k 1M0

10

20

30

40

50

60

70

PSRR

(dB)

FREQUENCY (Hz)

LOOP SUPPLY REJECTIONRATIO vs. FREQUENCY

(SYSTEM LEVEL) toc10

20mASTEP TRANSIENTRESPONSE OVER 500Ω LOAD

20ms/div

2V/div

toc11

VOUTN

VINSIDE

VBACKUP

ANALOG RATE OF CHANGE OVER 500Ω LOAD

WITH DIGITAL FILTER

20ms/div

200mV/div10x gain(AC COUPLED)

toc12

VOUTN

VINSIDE

VBACKUP

10kHZ SQUARE WAVE OVER 100Ω LOAD

100mV/div(AC-COUPLED)

50µs/div

toc14

VOUTN

VINSIDE

VBACKUP

0

5

10

15

20

25

30

-1800 -1200 -600 0 600 1200 1800

FREQ

UENC

Y (%

)

INPUT OFFSET VOLTAGE (µV)

OP1/OP2 INPUT OFFSETVOLTAGE HISTOGRAM

toc15



Typical Operating Characteristics (continued)


10

100

1000

10000

0.1 1 10 100 1000 10000

CAP

ACIT

ANC

E (p

F)

ISOLATION RESISTOR (Ω)

toc22

UNSTABLE

VCCI = 3.3VVCM = 1.65VAV = 1V/VRLOAD = ∞

OP1/OP2 CAPACITIVE LOADvs. ISOLATION RESISTOR

3.290

3.291

3.292

3.293

3.294

3.295

3.296

3.297

3.298

3.299

3.300

-40 -25 -10 5 20 35 50 65 80 95 110 125

OU

TPU

T VO

LTAG

E (V

)

TEMPERATURE (°C)

OP1/OP2 OUTPUT VOLTAGEHIGH vs. TEMPERATURE

toc19

RLOAD = 100kΩ

0

1

2

3

4

5

6

7

8

9

10

-40 -25 -10 5 20 35 50 65 80 95 110 125

OU

TPU

T VO

LTAG

E (m

V)

TEMPERATURE (°C)

OP1/OP2 OUTPUT VOLTAGELOW vs. TEMPERATURE

toc20

RLOAD = 100kΩ

10m 100m 1 10 100 1k 10k 100k 1M-225

-180

-135

-90

-45

0

45

90

135

180

225

-60

-40

-20

0

20

40

60

80

100

120

140

PHAS

E(°

)

GAI

N(d

B)

FREQUENCY (Hz)

GAIN

OP1/OP2 GAIN AND PHASEvs. FREQUENCY

toc21

AV = 1V/VRLOAD = 100kΩCLOAD = 10pF

PHASE

1.50

1.55

1.60

1.65

1.70

1.75

1.80

0 10 20 30 40 50 60 70 80 90 100

OU

TPU

T VO

LTAG

E (V

)

TIME (µs)

OP1/OP2 SMALL-SIGNALPULSE RESPONSE

toc23

AV = 1V/VCLOAD = 15pF

0.33

0.66

0.99

1.32

1.65

1.98

2.31

2.64

2.97

0 10 20 30 40 50 60 70 80 90 100

OU

TPU

T VO

LTAG

E (V

)

TIME (µs)

OP1/OP2 LARGE-SIGNALPULSE RESPONSE

toc24


0

5

10

15

20

25

30

35

0 0.04 0.08 0.12 0.16

FREQ

UEN

CY

(%)

INPUT BIAS CURRENT (pA)

OP1/OP2 INPUT BIASCURRENT HISTOGRAM

toc16

VCCI = 5.5VVCM = 2.75VTA = +25°C

-600

-400

-200

0

200

400

600

800

-0.1 0.4 0.9 1.4 1.9 2.4 2.9

INPU

T O

FFSE

T VO

LTAG

E (µ

V)

INPUT COMMON-MODE VOLTAGE (V)

-40°C 25°C 85°C 125°C

OP1/OP2 INPUT OFFSET VOLTAGEvs. COMMON-MODE VOLTAGE

toc17

-140

-120

-100

-80

-60

-40

-20

0

20

40

60

0 0.5 1 1.5 2 2.5 3

INPU

T BI

AS C

UR

REN

T (p

A)


-40°C 25°C 85°C 125°C

OP1/OP2 INPUT BIAS CURRENTvs. COMMON-MODE VOLTAGE

toc18





10

100

1000

10000

0.01 0.1 1 10 100

INPU

T VO

LTAG

E NO

ISE

(nV/

√Hz)

FREQUENCY (kHz)

toc25

AV = 4V/V

OP1/OP2 INPUT VOLTAGENOISE vs. FREQUENCY

1 10 100 1k 10k 100k0

10

20

30

40

50

60

70

80

90

PSRR

(dB)

FREQUENCY (Hz)

OP1/OP2 VCCI SUPPLY REJECTIONRATIO vs. FREQUENCY toc26

1 10 100 1k 10k 100k0

20

40

60

80

100

120

140

160

180

PSRR

(dB)

FREQUENCY (Hz)

OP1/OP2 VCC SUPPLY REJECTIONRATIO vs. FREQUENCY toc27

0

5

10

15

20

25

-5.8 -5.2 -4.6 -4.0 -3.4 -2.8 -2.2

FREQ

UENC

Y (%

)

INPUT OFFSET VOLTAGE (µV)

OP3 INPUT OFFSETVOLTAGE HISTOGRAM

toc28

0

5

10

15

20

25

3.31 3.42 3.53 3.64 3.75 3.86

FREQ

UENC

Y (%

)

INPUT BIAS CURRENT (pA)

OP3 INPUT BIASCURRENT HISTOGRAM

toc29

VCCI = 5.5VVCM = 2.75VTA = +25°C

-9

-7

-5

-3

-1

1

3

-0.1 0.3 0.7 1.1 1.5 1.9 2.3 2.7 3.1

INPU

T O

FFSE

T VO

LTAG

E (µ

V)


-40°C 25°C 85°C 125°C

OP3 INPUT OFFSET VOLTAGEvs. COMMON-MODE VOLTAGE

toc30

-160

-140

-120

-100

-80

-60

-40

-20

0

20

40

0 0.5 1 1.5 2 2.5 3

INPU

T BI

AS C

URRE

NT (

pA)


-40°C 25°C 85°C 125°C

OP3 INPUT BIAS CURRENTvs. COMMON-MODE VOLTAGE

toc31

3.295

3.296

3.297

3.298

3.299

3.300

3.301

-40 -25 -10 5 20 35 50 65 80 95 110 125

OUT

PUT

VOLT

AGE

(V)

TEMPERATURE (°C)

OP3 OUTPUT VOLTAGEHIGH vs. TEMPERATURE

toc32

RLOAD = 100kΩ

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-40 -25 -10 5 20 35 50 65 80 95 110 125

OUT

PUT

VOLT

AGE

(mV)

TEMPERATURE (°C)

OP1/OP2 OUTPUT VOLTAGELOW vs. TEMPERATURE

toc33

RLOAD = 100kΩ





10m 100m 1 10 100 1k 10k 100k 1M 10M-180

-135

-90

-45

0

45

90

135

180

225

270

-40

-20

0

20

40

60

80

100

120

140

160PH

ASE

(°)

GAI

N (d

B)

FREQUENCY (Hz)

GAIN

OP3 GAIN AND PHASEvs. FREQUENCY toc34

AV = 1V/VRLOAD = 100kΩCLOAD = 20pF

PHASE

100

1000

10000

0.1 1 10 100 1000 10000

CAPA

CITA

NCE

(pF)

ISOLATION RESISTOR (Ω)

toc35

UNSTABLE

VCCI = 3.3VVCM = 1.65VAV = 1V/VRLOAD = 100kΩ

OP3 CAPACITIVE LOADvs. ISOLATION RESISTOR

1.50

1.55

1.60

1.65

1.70

1.75

1.80

0 10 20 30 40 50 60 70 80 90 100

OUT

PUT

VOLT

AGE

(V)

TIME (µs)

OP3 SMALL-SIGNALPULSE RESPONSE

toc36


1 10 100 1k 10k 100k 1M0

10

20

30

40

50

60

70

80

90

100

110

120

PSRR

(dB)

FREQUENCY (Hz)

OP3 VCCI SUPPLY REJECTIONRATIO vs. FREQUENCY toc40

0.33

0.66

0.99

1.32

1.65

1.98

2.31

2.64

2.97

0 10 20 30 40 50 60 70 80 90 100

OUT

PUT

VOLT

AGE

(V)

TIME (µs)

OP3 LARGE-SIGNALPULSE RESPONSE

toc37


2.5000

2.5005

2.5010

2.5015

2.5020

2.5025

2.5030

3 3.5 4 4.5 5 5.5

OUT

PUT

VOLT

AGE

(V)

VCCI (V)

-40°C 25°C 85°C 125°C

VOLTAGE REFERENCELINE REGULATION

toc42

10

100

1000

10000

0.01 0.1 1 10 100

INPU

T VO

LTAG

E NO

ISE

(nV/

√Hz)

FREQUENCY (kHz)

toc38

OP3 INPUT VOLTAGENOISE vs. FREQUENCY

1s/div

OP3 0.1Hz TO 10HzINPUT VOLTAGE NOISE

toc39

0.1µV/div

1 10 100 1k 10k 100k 1M0

20

40

60

80

100

120

140

160

180

200

PSRR

(dB)

FREQUENCY (Hz)

OP3 VCC SUPPLY REJECTIONRATIO vs. FREQUENCY toc41





2.4985

2.4990

2.4995

2.5000

2.5005

2.5010

2.5015

2.5020

2.5025

0 100 200 300 400 500

OUT

PUT

VOLT

AGE

(V)

ILOAD (µA)

-40°C 25°C 85°C 125°C

VOLTAGE REFERENCELOAD REGULATION

toc43

VCCI = 5.5V

2.4985

2.4990

2.4995

2.5000

2.5005

2.5010

2.5015

2.5020

2.5025

0 100 200 300 400 500

OUT

PUT

VOLT

AGE

(V)

ILOAD (µA)

-40°C 25°C 85°C 125°C

VOLTAGE REFERENCELOAD REGULATION

toc44

VCCI = 3.0V

20µs/div

VOLTAGE REFERENCE LOADTRANSIENT RESPONSE

toc48

AC-COUPLED

ILOAD25µA/div

VREFO20mV/div

+25µA

-25µA

0

5

10

15

20

25

30

35

0.4 1.3 2.2 3.1 4.0 4.9 5.8

FREQ

UENC

Y (%

)

TEMPERATURE COEFFICIENT (ppm/°C)

VOLTAGE REFERENCE TEMPERATURECOEFFICIENT HISTOGRAM

toc45

0

5

10

15

20

25

-278 -234 -190 -146 -102 -58 -14

FREQ

UENC

Y (%

)

TEMPERATURE HYSTERESIS (ppm)

VOLTAGE REFERENCE TEMPERATUREHYSTERESIS HISTOGRAM

toc46

100µs/div

VOLTAGE REFERENCE LINETRANSIENT RESPONSE

toc47

VVCC2V/div

VREFO10mV/div

+20V

AC-COUPLEDCLDO = 0.32µF

+10V

1 10 100 1k 10k 100k 1M0

10

20

30

40

50

60

70

80

90

100

PSRR

(dB)

FREQUENCY (Hz)

VOLTAGE REFERENCE VCCI REJECTIONRATIO vs. FREQUENCY toc49

1s/div

VOLTAGE REFERENCE0.1Hz TO 10Hz OUTPUT NOISE

toc51

10µV/div

1 10 100 1k 10k 100k 1M0

20

40

60

80

100

120

140

160

180

PSRR

(dB)

FREQUENCY (Hz)

VOLTAGE REFERENCE VCC REJECTIONRATIO vs. FREQUENCY toc50





0.1

1.0

10.0

100.0

0.01 0.1 1 10 100

VOLT

AGE

REFE

RENC

E NO

ISE

(µV/

√Hz)

FREQUENCY (kHz)

toc52

VOLTAGE REFERENCENOISE vs. FREQUENCY

0.997

0.998

0.999

1.000

1.001

-40 -25 -10 5 20 35 50 65 80 95 110 125

INPU

T TH

RESH

OLD

VO

LTAG

E (V

)

TEMPERATURE (°C)

PWMA/PWMB INPUT THRESHOLDVOLTAGE vs. TEMPERATURE

toc53

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

-40 -25 -10 5 20 35 50 65 80 95 110 125

OUT

PUT

VOLT

AGE

MAT

CHIN

G (

mV)

TEMPERATURE (°C)

PWMA-PWMB OUTPUT HIGH LEVELMATCHING vs. TEMPERATURE

toc57

RLOAD = 100kΩ

-0.40

-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

-40 -25 -10 5 20 35 50 65 80 95 110 125

INPU

T BI

AS C

URRE

NT (

nA)

TEMPERATURE (°C)

PWMA/PWMB INPUT BIASCURRENT vs. TEMPERATURE

toc54

2.480

2.482

2.484

2.486

2.488

2.490

2.492

2.494

2.496

2.498

2.500

0 50 100 150 200

OUT

PUT

VOLT

AGE

(V)

ILOAD (µA)

-40°C 25°C 85°C 125°C

PWMA/PWMB OUTPUT VOLTAGEHIGH vs. LOAD CURRENT

toc60

2.495

2.496

2.497

2.498

2.499

2.500

2.501

-40 -25 -10 5 20 35 50 65 80 95 110 125

OUT

PUT

VOLT

AGE

(V)

TEMPERATURE (°C)

PWMA/PWMB OUTPUT VOLTAGEHIGH vs. TEMPERATURE

toc55

RLOAD = 100kΩ

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

-40 -25 -10 5 20 35 50 65 80 95 110 125

OUT

PUT

VOLT

AGE

(mV)

TEMPERATURE (°C)

PWMA/PWMB OUTPUT VOLTAGELOW vs. TEMPERATURE

toc56

RLOAD = 100kΩ

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

-40 -25 -10 5 20 35 50 65 80 95 110 125

OUT

PUT

VOLT

AGE

MAT

CHIN

G (

mV)

TEMPERATURE (°C)

PWMA-PWMB OUTPUT LOW LEVELMATCHING vs. TEMPERATURE

toc58

RL = 100kΩ

0

2

4

6

8

10

12

14

16

-200 -150 -100 -50 0

OUT

PUT

VOLT

AGE

(mV)

ILOAD (µA)

-40°C 25°C 85°C 125°C

PWMA/PWMB OUTPUT VOLTAGELOW vs. LOAD CURRENT

toc59





-13.0

-12.5

-12.0

-11.5

-11.0

-10.5

-10.0

-9.5

-9.0

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

-40 -25 -10 5 20 35 50 65 80 95 110 125

CURR

ENT

FRO

M V

REF

(mA)

CURR

ENT

TO G

ND (m

A)

TEMPERATURE (°C)

SHORT TO GND SHORT TO VREF

PWMA/PWMB SHORT-CIRCUITCURRENT vs. TEMPERATURE

toc61

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 200 400 600 800 1000

VOLT

AGE

(V)

TIME (ns)

INPUT OUTPUT

PWMA/PWMB INPUT/OUTPUTWAVEFORMS

toc62

CODE = 1CLOAD = 10pF

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

-40 -25 -10 5 20 35 50 65 80 95 110 125

PULS

E W

IDTH

MAT

CHIN

G (

ns)

TEMPERATURE (°C)

5% DUTY CYCLE50% DUTY CYCLE95% DUTY CYCLE

PWMA-PWMB PULSE WIDTHMATCHING vs. TEMPERATURE

toc66

RLOAD = 100kΩCLOAD = 10pFPERIOD = 100µs

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5 6 7

VOLT

AGE

(V)

TIME (µs)

INPUT OUTPUT

PWMA/PWMB INPUT/OUTPUTWAVEFORMS

toc63

CODE = 10CLOAD = 10pF

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

-40 -25 -10 5 20 35 50 65 80 95 110 125

PRO

PAG

ATIO

N DE

LAY

MAT

CHIN

G (

ns)

TEMPERATURE (°C)

PWMA-PWMB PROPAGATION DELAYMATCHING vs. TEMPERATURE

toc64

RLOAD = 100kΩCLOAD = 10pF

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

-40 -25 -10 5 20 35 50 65 80 95 110 125

RISE

AND

FAL

L TI

ME

MAT

CHIN

G (

ns)

TEMPERATURE (°C)

RISE TIME MATCHING

FALL TIME MATCHING

PWMA-PWMB RISE AND FALL TIMEMATCHING vs. TEMPERATURE

toc65

RLOAD = 100kΩCLOAD = 10pF

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

-40 -25 -10 5 20 35 50 65 80 95 110 125

INPU

T O

FFSE

T VO

LTAG

E (m

V)

TEMPERATURE (°C)

COMP1/COMP2 INPUT OFFSETVOLTAGE vs. TEMPERATURE

toc67

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

-40 -25 -10 5 20 35 50 65 80 95 110 125

INPU

T BI

AS C

URRE

NT (

nA)

TEMPERATURE (°C)

COMP1/COMP2 INPUT BIASCURRENT vs. TEMPERATURE

toc68

0

50

100

150

200

250

300

350

-200 -150 -100 -50 0

OUT

PUT

VOLT

AGE

(mV)

ILOAD (µA)

-40°C 25°C 85°C 125°C

COMP1/COMP2 OUTPUT VOLTAGELOW vs. LOAD CURRENT

toc69





2.95

3.00

3.05

3.10

3.15

3.20

3.25

3.30

3.35

0 50 100 150 200

OUT

PUT

VOLT

AGE

(V)

ILOAD (µA)

-40°C 25°C 85°C 125°C

COMP1/COMP2 OUTPUT VOLTAGEHIGH vs. LOAD CURRENT

toc70

400

600

800

1000

1200

1400

1600

1800

2000

2200

-40 -25 -10 5 20 35 50 65 80 95 110 125

PRO

PAG

ATIO

N DE

LAY

(ns)

TEMPERATURE (°C)

LOW TO HIGH

HIGH TO LOW

COMP1/COMP2 PROPAGATIONDELAY vs. TEMPERATURE

toc74

CLOAD = 10pF

-2.12

-2.10

-2.08

-2.06

-2.04

-2.02

-2.00

-1.98

1.98

2.00

2.02

2.04

2.06

2.08

2.10

2.12

-40 -25 -10 5 20 35 50 65 80 95 110 125

CURR

ENT

FRO

M V

DD(m

A)

CURR

ENT

TO G

ND (m

A)

TEMPERATURE (°C)

SHORT TO GND SHORT TO VDD

COMP1/COMP2 SHORT-CIRCUITCURRENT vs. TEMPERATURE

toc71

3.296

3.300

3.304

3.308

3.312

3.316

3.320

3.324

0 0.5 1 1.5 2 2.5 3 3.5 4

OUT

PUT

VOLT

AGE

(V)

ILDO (mA)

-40°C 25°C 85°C 125°C

LDO LOAD REGULATIONtoc77

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 0.5 1 1.5 2 2.5 3

VOLT

AGE

(V)

TIME (µs)

POSITIVE INPUT

NEGATIVE INPUT

OUTPUT

COMP1/COMP2 INPUT/OUTPUTWAVEFORMS (TPD+)

toc72

CLOAD = 10pF

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 0.25 0.5 0.75 1 1.25 1.5

VOLT

AGE

(V)

TIME (µs)

POSITIVE INPUT

NEGATIVE INPUT

OUTPUT

COMP1/COMP2 INPUT/OUTPUTWAVEFORMS (TPD-)

toc73

CLOAD = 10pF

3.300

3.302

3.304

3.306

3.308

3.310

3.312

3.314

3.316

3.318

-40 -25 -10 5 20 35 50 65 80 95 110 125

OUT

PUT

VOLT

AGE

(V)

TEMPERATURE (°C)

0.1mA LOAD 4mA LOAD

LDO OUTPUT VOLTAGEvs. TEMPERATURE

toc78

3.290

3.295

3.300

3.305

3.310

3.315

3.320

3.325

3.330

4 8 12 16 20 24 28 32 36

OUT

PUT

VOLT

AGE

(V)

VCC (V)

-40°C 25°C 85°C 125°C

LDO LINE REGULATIONtoc75

ILDO = 0.1mA

3.290

3.295

3.300

3.305

3.310

3.315

3.320

3.325

3.330

4 8 12 16 20 24 28 32 36

OUT

PUT

VOLT

AGE

(V)

VCC (V)

-40°C 25°C 85°C 125°C

LDO LINE REGULATIONtoc76

ILDO = 4mA





100µs/div

VCC VCCI

LDO LINETRANSIENT RESPONSE

toc79

AC-COUPLEDCLOAD = 0.32µF

VVCC2V/div

VVCCI20mV/div

+15V

+9V

105

115

125

135

145

155

165

175

185

195

4 8 12 16 20 24 28 32 36

SUPP

LY C

URRE

NT (

µA)

VCC (V)

-40°C 25°C 85°C 125°C

QUIESCENT CURRENTvs. VCC VOLTAGE

toc83

PWM CONDITIONERS SHUT DOWN

40µs/div

LOAD CURRENT

VCCI

LDO LOADTRANSIENT RESPONSE

toc80

AC-COUPLEDCLOAD = 0.32µF

ILDO2mA/div

VVCCI20mV/div

+4.0mA

+0.4mA

1 10 100 1k 10k 100k 1M0

10

20

30

40

50

60

70

80

90

100

PSRR

(dB)

FREQUENCY (Hz)

LDO VCC SUPPLY REJECTIONRATIO vs. FREQUENCY toc81

CLOAD = 0.32µFR1 = 510kΩR2 = 300kΩ

130

140

150

160

170

180

190

200

210

220

4 8 12 16 20 24 28 32 36

SUPP

LY C

URRE

NT (

µA)

VCC (V)

-40°C 25°C 85°C 125°C

QUIESCENT CURRENTvs. VCC VOLTAGE

toc82

140

150

160

170

180

190

200

210

220

-40 -25 -10 5 20 35 50 65 80 95 110 125

SUPP

LY C

URRE

NT (

µA)

TEMPERATURE (°C)

QUIESCENT CURRENTvs. TEMPERATURE

toc84

-1012345678910111213

-0.50.00.51.01.52.02.53.03.54.04.55.05.56.06.5

0 100 200 300 400 500 600 700 800 900 1000

VCC

(V)

OUT

PUT

VOLT

AGE

(V)

TIME (µs)

VCCI

REFO

PWRGOOD

VCC

POWER-UP WAVEFORMS(VCC, VCCI, REFO, PWRGOOD)

toc85

-1012345678910111213

-0.50.00.51.01.52.02.53.03.54.04.55.05.56.06.5

0 100 200 300 400 500 600 700 800 900 1000

VCC

(V)

OUT

PUT

VOLT

AGE

(V)

TIME (µs)

VCCIOP1OOP2OOP3OVCC

POWER-UP WAVEFORMS(VCC, VCCI, OP1O, OP2O, OP3O)

toc86

OPAMP AV = 1V/VVOP1P = 2.5VVOP2P = 1.5VVOP3P = 1.65V

-1012345678910111213

-0.50.00.51.01.52.02.53.03.54.04.55.05.56.06.5

0 100 200 300 400 500 600 700 800 900 1000

VCC

(V)

OUT

PUT

VOLT

AGE

(V)

TIME (µs)

VCCI

PWMAO

COMP1O

VCC

POWER-UP WAVEFORMS(VCC, VCCI, PWMAO, COMP1O)

toc87




PIN # NAME DESCRIPTION1 COMP2P Comparator 2 noninverting input2 COMP1N Comparator 1 inverting input3 COMP1P Comparator 1 noninverting input4 COMP2O Comparator 2 output5 COMP1O Comparator 1 output6 VDD Comparator Output Supply Voltage. Add a 0.1µF bypass cap from VDD to GND.7 VCC Positive Supply Voltage at Internal LDO Input. Add a 1µF bypass cap from VCC to GND.8 LDOFB LDO feedback voltage. Connect to resistor divider between VCCI and GND.9 N/C Not connected

10 VCCID Digital power input. Connect this pin to VCCI.11 VCCI LDO output. Add a 0.22µF bypass cap from VCCI to GND.12 REFGND Internal reference ground. Connect to GND.13 REFO Internal reference output. 14 I/C Internally connected pin. Connect this pin to GND.15 I/C Internally connected pin. Connect this pin to GND.16 I/C Internally connected pin. Connect this pin to GND.17 OP3P Op Amp 3 noninverting input18 OP3N Op Amp 3 inverting input19 OP3O Op Amp 3 output20 OP2O Op Amp 2 output

TOP VIEW

9

11

10

12

13

14

15

16

N/C+

VCCID

VCCI

REFGND

REFO

I/C

I/C

I/C

COMP2N

PWMBP

PWMAP

PWMBO

PWMAO

SHDN

OP1O

OP1N

30

29

32

31

28

27

26

25

1 2 3 4 5 6 7 8

24 23 22 21 20 19 18 17

LDO

FB

VCC

VDD

CO

MP1

O

CO

MP2

O

CO

MP1

P

CO

MP1

N

CO

MP2

P

OP3

P

OP3

N

OP3

O

OP2

O

OP2

N

OP2

P

PWR

GO

OD

OP1

PMAX12900

EP



Pin Configuration

Pin Description

Detailed DescriptionThe MAX12900 is an ultra-low-power, highly integrated 4-20mA transmitter. The MAX12900 integrates ten building blocks in a small package: a wide supply voltage range LDO, two comparators for PWM conditioning (PWMA and PWMB), two low-drift, general purpose op amps (OP1 and OP2), one zero-drift, wide-bandwidth op amp (OP3), two diagnostic comparators (COMP1 and COMP2), a power-up sequencer with power good output, and a low-drift voltage reference. There are many ways that one can connect these building blocks to optimize overall functionality and performance of the MAX12900 for a specific application.

Power-Up SequencerThe power-up sequencer keeps all op amp and PWM outputs at Hi-Z, and outputs of the comparators low during power-up until VCCI reaches 90% of its final value. After that, the PWRGOOD signal is asserted and all outputs become controlled by their inputs. The PWRGOOD signal is delayed by 0.7ms (typ) after VCCI reaches 90% of its final value, thus allowing for external loops controlled by the MAX12900 to stabilize before signaling that the part is ready.

Note that external components, such as a sensor or microcontroller, should not draw load current from VCCI until the PWRGOOD signal has been asserted.

PWM ConditionersThe PWM conditioners generate ground level when the input is below the threshold voltage, and generate VREF when the input is above the threshold voltage. The PWM conditioners can be powered down by setting the SHDN pin low. The PWM outputs are Hi-Z during shutdown.

General Purpose Op Amps (OP1, OP2)The general purpose op amps, OP1 and OP2, feature a low operating supply voltage, low input bias current, rail-to-rail outputs, and a maximized ratio of Gain Bandwidth Product (GBWP) to supply current. These CMOS devices feature ultra-low input bias current up to 15pA at 85°C. They are unity-gain stable with a 200kHz GBWP, driving capacitive loads up to 100pF. The input common mode voltage range can extend 100mV below ground with excellent common-mode rejection. The OP1 and OP2 op amps can drive the output to within 25mV of both supply rails with a 100kΩ load. Op amp settling time depends primarily on the output voltage and is slew-rate limited.The general-purpose op amps can be used as PWM filters, linear filters/amplifiers, or as linear or shunt regulator controllers, refer to the Application Information section.

PIN # NAME DESCRIPTION21 OP2N Op Amp 2 inverting input22 OP2P Op Amp 2 noninverting input23 PWRGOOD Active-high output signal that indicates when the MAX12900 is ready.24 OP1P Op Amp 1 non-inverting input25 OP1N Op Amp 1 inverting input26 OP1O Op Amp1 output

27 SHDN Active-Low, Shutdown Input for PWM Conditioners. PWM circuitry powers down and outputs go to Hi-Z state when this pin is low.

28 PWMAO PWM conditioner output A29 PWMBO PWM conditioner output B30 PWMAP PWM conditioner input A31 PWMBP PWM conditioner input B32 COMP2N Comparator 2 inverting inputEP GND Exposed pad, chip ground.



Pin Description (continued)

Zero-Drift High Bandwidth Op Amp (OP3)The zero-drift, wide bandwidth op amp OP3 uses an innovative auto-zero technique that allows precision and low noise with a minimum amount of power. The ultra-low input offset voltage, offset drift, and 1/f noise allow for building a highly accurate current transmitter. The high GBWP allows for noise suppression over a wider frequency band. The OP3 amplifier achieves rail-to-rail performance at the output. Driving large capacitive loads can cause instability in many op amps. The OP3 amplifier is stable with capacitive loads up to 300pF. Stability with higher capacitive loads can be improved by adding an isolation resistor in series with the op amp output.

Low-Drift 2.5V Voltage ReferenceThe precision bandgap reference uses a proprietary curvature-correction circuit and laser-trimmed thin-film resistors, resulting in a low temperature coefficient of <10ppm/°C, and initial accuracy of better than 0.2%. The reference can sink and source up to 500µA, making it attractive for use in low-voltage applications. It is stable for capacitive loads up to 2nF. In applications where the load can experience step changes, an output capacitor will reduce the amount of overshoot (or undershoot) and assist the circuit’s transient response. The reference typically turns on and settles to within 0.1% of its final value in 220µs.

General-Purpose ComparatorsThe comparators COMP1 and COMP2 feature a 2µs propagation delay. Two independent rails supply each comparator. The input stage operates with VCCI from 3.0V to 5.5V, and the output drivers operate with VDD from 1.8V to 3.6V. This allows for a direct connection to a microcontroller. The internal output driver allows for rail-to-rail output swings with up to 100µA load. Both comparators offer a push-pull output that sinks and sources current.

The input common-mode voltage range for these devices extends from 0V to VCCI - 1.3V. The MAX12900’s com-parators can operate at any differential input voltage with-in these limits. Input bias current is typically less than 1nA. These comparators can be used for VCC, VDD or VREF voltage monitoring or other diagnostic functions, providing status information to the microcontroller.

LDOAll components of the MAX12900 are powered from an integrated LDO that generates a 3.0V to 5.5V VCCI volt-age from an input VCC voltage of 4.0V to 36V. The LDO provides a clean supply for sensitive analog circuitry. The output of the LDO is set by external resistors and can be selected using the following equation:

( )OUTV 1.212V 1 R1/R2= × +

Where, 1.212V is an internal reference voltage, R1 and R2 form a resistor divider providing feedback voltage to close the LDO loop, refer to the typical application diagrams. It is recommended that R2 be less than or equal to 470kΩ. For example, for VCCI = 3.3V, R1 = 698k and R2 = 402k can be used from standard 1% E96 resistor series values.

Application InformationLoop-Powered 4-20mA Sensor Transmitter with PWM inputsOne of the possible implementations of a loop powered 4-20mA sensor transmitter is shown in Figure 2. In this application diagram, the PWM inputs from a microcontroller are reshaped by the conditioners, filtered by the OP1 op amp and converted to an analog voltage. The voltage is then converted to a 4-20mA loop current by OP3, an external transistor Q1 and a current sense resistor RSENSE.



Figure 2. Loop-Powered 4-20mA Transmitter with Two PWM Inputs

MAX12900VCCID PWRGOOD VD D

SHDN

REFO

OP1P

OP1N

OP1O

OP3P

OP3NOP3O

OP2P

OP2NOP2O

PWM BOPWMBP

PWMAOPWMAP

PWM11.5k

22.6k

OP1

294k

OP2

OP3

TO MICROCONTROLLER

1M4.99k

24.9k

24.9k

100k

R EFO/2

LDO

R1

R2

LDOFB

VCC

VCCI

COMP2NCOM P2O

COMP2P

COMP1N

COMP1PCOM P1O

VCCI

VCC

100

511k

FSK_OUT

POWER-UPSEQUENCER

REFGN DEP

4-20mA LOOP

2.5VREF

R3 22.6k

R4 1.5M

R6

R5

R9

294kR10

R8

100kR7

24.9

R11

R12

R13R16

RSENSE

402k

R14

R15

R17D1

Q1

C6

C1

C2

C3

C4

C5



The component selection of this circuit is as follows.Let us assume the loop current range is 2.5mA to 27.5mA including NAMUR burnout detection. With the 24.9Ω RSENSE resistor and the 2.5mA to 27.5mA loop current range, the non-inverting input of OP3 (OP3P) should be in the range 62.25mV (2.5mA x 24.9Ω = 62.25mV) to 684.75mV (27.5mA x 24.9Ω = 684.75mV).The loop current (Iloop) has two components: offset current generated by the reference output (Ioffset) and PWM signals converted to current (IPWMA, IPWMB).

Iloop = Ioffset + IPWMA + IPWMBAfter power-up, assuming the PWM signals do not contribute to the loop current, the initial 2.5mA offset current is generated by the reference voltage as follows:

×=

× SENSE

REFO R13IoffsetR8 R

The PWM currents are given by

× × × =×

× × × =×

PWMASENSE

PWMBSENSE

R5PWMADC REFO R13R3I

R7 R

R5PWMBDC REFO R13R4I

R7 R

where, PWMADC and PWMBDC are the PWM duty cycles.

DAC Implementation with PWM and Low-Pass FilterThe sensor data received from the microcontroller can be arranged into a coarse and a fine PWM signal.Both the coarse and fine signals can have up to 8 bits of resolution. The PWM signals are then converted to their voltage level representations via a LPF. The PWM outputs from the MAX12900 connect to the LPF through two gain setting resistors with ratios up to 1:256; the voltage levels at the output of the LPF are proportional to the PWM duty cycles.The application diagram in Figure 2 shows an implementation of a 14-bit resolution signal path. The PWMAP input receives the coarse signal with 8-bits of resolution, and the PWMBP input receives the fine signal with 6-bits of resolution. A 1:66 ratio is used for the two gain setting resistors.The coarse gain is set to 1 by using a 22.6kΩ gain resistor R3 and a 22.6kΩ feedback resistor R5, while the fine gain is set to 1/66 by using a 1.5MΩ gain resistor R4. The two PWM outputs are summed via the 22.6kΩ feedback resistor R5 of OP1.The PWM frequency and filter parameters must satisfy the 4–20mA current loop noise requirements. In this example, the PWM frequency is 10kHz and the 4–20mA transmitter is designed to meet the HART specification. Consequently, the broadband noise of the current loop during silence must be below 138mVRMS, and the in-band noise (500Hz–10kHz) must be below 2.2mVRMS across a 500Ω loop load. In order to reduce the noise level to 2.2mVRMS in-band, the LPF should suppress the noise by more than 60dB (2.5V/2.2mV = 1136.4 or 61dB). Therefore, the cut-off frequency of the LPF should be less than 70Hz with a 40dB/decade roll-off slope. OP1 implements a second-order multi-feedback LPF.



Voltage-Controlled Current SourceThe integrated OP3 op amp can be combined with an external current modulating transistor Q1 to implement a precision voltage controlled current source. Q1 can be either an N-MOSFET or a bipolar NPN transistor and needs to satisfy the peak voltage and power dissipation criteria of the current loop. OP3 and Q1, in combination with a few external components, provide an optimal point to compensate the current loop.

Loop Current DiagnosticIn the application example of Figure 2, the second general purpose amplifier (OP2) is used for current diagnostics and provides feedback to the microcontroller.

Connection with a SensorThe MAX12900 can work with any kind of sensor trans-mitter, even though it is designed with smart sensors in mind. A smart sensor means that it has an integrated microcontroller and the ability to provide either linear analog or PWM output. If the total current consumption of the transmitter is less than 4mA, power to the sensor and the digital VDD supply can be provided directly from the VCCI pin. If the transmitter requires more than 4mA, an external dc-dc switching converter can be used. Such

a scenario is shown in the application circuit in Figure 3, where OP2 is utilized as a linear voltage regulator and the dc-dc converter powers the microcontroller and drives the VDD supply pin.

Loop Powered 4-20mA Transmitter for Explosion-Proof DevicesIf the sensor is to be deployed in hazardous or explosive areas, it must use additional protective components to limit the electrical energy from short circuit or failure conditions, and to prevent sparks that could cause an explosive atmosphere to ignite.Figure 4 shows an application circuit with improved protection in hazardous environments. In order to limit the electrical energy that goes to the sensor transmitter, an additional Q2 transistor and Zener diodes are added. Typically, a Zener diode should have a clamping voltage from 5V to 12V. In this case, both Q1 and Q2 transistors are the current modulating elements of the circuit. The total 4-20mA loop current is the sum of the current flowing through the Zener diodes, the Q1 transistor and the sensor. Each current path is protected by limiting resistors. Most of the power dissipation is spread out through Q1, Q2 and the Zener diodes, which makes the system design more robust.



Figure 3. Loop-Powered 4-20mA Transmitter with an External Voltage Regulator

MAX12900

SHDN

REFO

OP1P

OP1N

OP1O

OP3P

OP3NOP3O

OP2P

OP2NOP2O

PWMBOPWMBP

PWMAOPWMAP

PWM11.5k

22.6k

OP1

294k

OP2

OP31M4.99k

24.9k

24.9k

REFO/2

LDO

R1

R2

LDOFB

VCCVCCI

COMP2NCOMP2O

COMP2P

COMP1N

COMP1PCOMP1O

VCCI

VCC

511k

FSK_OUT

4-20mA LOOP

2.5VREF

R3 22.6k

R4 1.5M

R6

R5

R9

294kR10

R8

100kR7

24.9

R11

R12

R13R16

RSENSE

100R14

R15

R17

REFO

OPTIONALDC/DC

TO SENS OR/MICROCONTROLLER

VCCI

RLIM

D1

C1

C2

C3

C4

C5

C6

C7

Q1

Q2

Q3

VDD



Figure 4. Loop-Powered 4-20mA Transmitter for Hazardous Environments

MAX12900

SHDN

REFO

OP1P

OP1N

OP1O

OP3P

OP3NOP3O

PWMBOPWMBP

PWMAOPWMAP

PWM11.5k

22.6k

OP1

294k OP31M4.99k

24.9k

24.9k

REFO/2

LDO

R1

R2

LDOFB

VCCVCCI

COMP2NCOMP2O

COMP2P

COMP1N

COMP1PCOMP1O

VCCI

VCC

511k

FSK_OUT

4-20mA LOOP

2.5VREF

R3 22.6k

R4 1.5M

R6

R5

R9

294kR10

R8

100kR7

24.9

R11

R12

R13R16

RSENSE

100

RLIM

R17

TO SENS OR /MICROCONTROLLER

VCCI

12V

OP2P

OP2NOP2OOP2 TO MICROCONTROLLER

100k

402k

R14

R15

R18

R19

C1

C2

C3

C4

C5

D1 D2 D3

C6

Q2

Q1

D4 D5 D6



+ Denotes a lead(Pb)-free/RoHS-compliant package.T = Tape and Reel

PART PACKAGE BODY SIZE PIN PITCH TEMP RANGE (°C)MAX12900AATJ+ TQFN32 5mm x 5mm 0.5mm -40 to +125

MAX12900AATJ+T TQFN32 5mm x 5mm 0.5mm -40 to +125



Ordering Information

Chip InformationPROCESS: BiCMOS

REVISIONNUMBER

REVISIONDATE DESCRIPTION PAGES

CHANGED0 9/17 Initial release —1 10/17 Updated title of data sheet 1–302 3/18 Updated Equation 3 26

Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.

Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2018 Maxim Integrated Products, Inc. 31


Revision History

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.

max12900 ultra-low-power 4-20a sensor transitter package: 5mm x 5mm x 0.8mm 32-pin tqfn applications...

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