table of contents - gm systems llclt1004-1.2 as1004-1.2 lt1004-2.5 as1004-2.5 uc384x as384x unitrode...

1

Table of Contents

Table of Content s ..................................................................................................... 1

Introductio n .............................................................................................................. 3

General Ordering Informatio n ................................................................................. 4

Package Marking Informatio n ................................................................................. 5

Alternate Source and Product Cross-Referenc e .................................................. 6

Product Status Definition s ...................................................................................... 7

Data Sheets - Title Page

AS431 Precision Adjustable Shunt Reference ........................................................... 1

AS1431 Precision Adjustable Shunt Reference ......................................................... 9

AS2431 Precision Adjustable Shunt Reference ...................................................... 17

AS432 1.25V Precision Adjustable Shunt Reference ............................................ 25

AS1004 Micropower Precision Reference ............................................................... 29

AS2842/3/4/5 Current Mode Controller ................................................................... 37

AS3842/3/4/5 Current Mode Controller ................................................................... 57

AS2208 (Preliminary) Current Mode Controller ....................................................... 77

AS2214 Current Mode Controller ............................................................................. 83

AS2316/33/50 Secondary Side Housekeeping Circuit ............................................ 91

AS300 Shunt Temperature Sensor ........................................................................ 101

AS273 Over-Temperature Detector........................................................................ 107

AS17XX Semi-Custom Bipolar Array ..................................................................... 119

2

Table of Contents

Application Notes

AN1: AS431 General Application Information ........................................................ 141

AN2: Secondary Side Error Amplifier Using the AS431 ......................................... 147

AN3: Noise and Stability Considerations Using the AS384X ................................. 151

AN4: AS384X/UC384X Compatibilbity Issues ....................................................... 157

AN5: Switching Power Supply Control Loop Design (AS3842) ............................. 161

Appendix

Package Outline Drawings ..................................................................................... 173

Quality Assurance and Reliability Program ............................................................ 181

3

Introduction

Astec Semiconductor Division (ASD) was chartered in 1983 to designand manufacture high quality power management integrated circuitsfor the Astec family of power supplies.

Extending from this charter, ASD has become power managementspecialists, developing semiconductor products optimized for thespecific need of all customers in power supply, lighting ballast,temperature controllers and consumer electronic applications. Ourproducts are built on modern Bipolar, BiCMOS and CMOS technolo-gies. ASD provides their customers products and services built to thehighest standards of quality and reliability.

Our goal is to provide quality, technology and predictability in ourpursuit of customer satisfaction.

Andrew DavisPresidentAstec Semiconductor Division

4

General Ordering Information

Order EntryProducts contained within this data book can be ordered from:

Astec Semiconductor255 Sinclair Frontage RoadMilpitas, California 95035 USAPhone: 408-263-8300Facsimile: 408-263-8340

Ordering InformationMinimum engineering order: 50 pieces (product samples available upon request)

Minimum production order: 500 pieces

Each item ordered must appear exactly as listed in the data sheet

F.O.B.: Milpitas, California

Part Number InformationXX XXXX -XX

Package Style

Generic or Product Part Number

DesignatorUC, TL, LM, and LT are industry standard second source devicesAS are proprietary or improved devices

Package Suffix ExplanationLetter Designation Description

N 8, 14, 16, 18, and 20 Lead Plastic DIPD 8, 14, and 16 Lead Plastic Narrow Body SOICDW 16, 18, and 20 Lead Plastic Wide Body SOICLP TO-92 Plastic (3 Lead)HP TO-237 Plastic (3 Lead, TO-92 with Top Heat Spreader)VS SOT-23 Plastic (3 Lead)S SOT-89 Plastic (3 Lead with Heat Spreader)G SOT-223 Plastic (3 Lead with Heat Spreader)

5

Package Marking InformationPackage Marking ExplanationPackage marking provides a consistent way of identifying product types and managing lottraceability. All Astec products, with the exception of the SOT-23 and SOT-89 packages, aremarked with product type, lot number, date code, and country of origin. Each assembly lot in theSOT-23 and SOT-89 packages, receives a unique alpha-numeric code which is recorded in a database for cross reference to lot number, date code, and country of origin. A complete marking formattable is shown below.

8, 14, 16, 18, and 20Lead Plastic DIP:

Top- Astec Logo

Product Name

Lot Identificaton Code

Bottom- Lot Identification Code

Country of Origin

Date Code

8, 14, and 16 Lead PlasticNarrow Body SOIC:

Top- Product Name


Bottom- Date Code

Country of Origin

16, 18, and 20 Lead PlasticWide Body SOIC:

Top- Astec Logo

Product Name


Bottom- Lot Identification Code

Country of Origin

Date Code

TO-92/237 Plastic (3 Lead):

Face- Astec Logo

Product Name


Country of Origin

Date Code

SOT-23 Plastic (3 Lead):

Top- Log Book Code

SOT-89 Plastic(3 Lead with Heat Spreader):

Top- Product Name

Log Book Code

SOT-223 Plastic(3 Lead with Heat Spreader):

Top- Product Name


Bottom- Date Code

Country of Origin

6

Alternate Source and Product Cross-ReferenceASD Direct ASD Direct ASD Direct

P/N Replacement Part P/N Replacement Part P/N Replacement Part

Cherry Semiconductor

CS384XA AS384X

CS384X AS384X

Hitachi

HA17431 A431

HA17384 AS3842

HA17345 AS3843

Linear Techology

LM385-1.2 AS1004-1.2

LM385-2.5 AS1004-2.5

LT1004-1.2 AS1004-1.2

LT1004-2.5 AS1004-2.5

LT1431CZ AS1431*

LT1242 AS3842*

LT1243 AS3843*

LT1244 AS3844*

LT1245 AS3845*

Motorola Semiconductor

TL431 A431

TL431A A431

UC384X AS384X

UC384XA AS384X

National Semiconductor

LM431A A431

LM385-1.2 AS1004-1.2

LM385-2.5 AS1004-2.5

Samsung Semiconductor

SKA431 A431

KA384X AS384X

Texas Instruments

TL431 A431

TL431A A431

TL1431 AS1431

LM385-1.2 AS1004-1.2

LM385-2.5 AS1004-2.5

LT1004-1.2 AS1004-1.2

LT1004-2.5 AS1004-2.5

UC384X AS384X

Unitrode

UC384X AS384X

UC384XA AS384X*

* Similar Device: Please consult data sheet to determine the suitability of replacement for specific applications

7

Product Status Definitions

This data sheet contains the design specifica-tions for product development. These specifica-tions are subject to change. Further informationwill be published upon product release.

This data sheet contains preliminary data. Supple-mentary data will be published at a later date.Astec Semiconductor reserves the right to makechanges at any time without notice in order toimprove design and supply the best product pos-sible.

Definition of Terms

Data Sheet Identification Product Status Definition

Proposed In Design

Preliminary First Production

No Identification Full Production This data sheet contains final specifications andcomplete typical curves. Astec Semiconductorreserves the right to make changes at any timewithout notice in order to improve design andsupply the best product possible.

1ASTEC Semiconductor

AS431Precision Adjustable Shunt Reference

Features¥ Temperature-compensated: 30 ppm/¡C¥ Trimmed bandgap reference¥ Internal amplifier with 150 mA capability¥ Multiple temperature ranges¥ Low frequency dynamic output impedance:

< 150 m½

¥ Low output noise¥ Robust ESD protection

DescriptionThe AS431 is a three-terminal adjustable shunt regulator providing a highlyaccurate bandgap reference. The adjustable shunt regulator is ideal for a widevariety of linear applications that can be implemented using external compo-nents to obtain adjustable currents and voltages.

In the standard shunt configuration, the combination of low temperature coef-ficient (TC), sharp turn-on characteristics, low output impedance and pro-grammable output voltage make this precision reference a perfect zener diodereplacement.

The AS431 precision adjustable shunt reference is offered in four bandgap tol-erances: ±0.25%, ±0.5%, ±1.0%, and ±2.0%.

Pin Configuration Ñ Top view

Ordering Information

CATHODE

TO-92 (LP) SOIC (D)

ANODE

REFERENCE

CATHODE

REFERENCE

ANODE

ANODE

N/C

CATHODE

ANODE

ANODE

N/C

SOT-89 (S)SOT-23/5L (DBV)

ANODE

REFERENCE

1

2

3

4

8

7

6

5

REFERENCE

ANODE

N/C

N/C

CATHODE

Circuit Type: Precision Adjustable Shunt Regulator

Temperature Range: A B C

Bandgap Tolerance: 2 1 R5 R25

= 0°C to 70°C= 0°C to 105°C= –40°C to +85°C

= ±2%= ±1%= ±0.5%= ±0.25%

Packaging Option: A B T 7 13

Package Style: D DBV LP S

= Ammo Pack= Bulk= Tube= Tape and Reel (7" Reel Dia)= Tape and Reel (13" Reel Dia)

= SOIC= SOT-23/5L= TO-92= SOT-89

AS431 A 2 D 7

SEMICONDUCTOR


AS431 Precision Adjustable Shunt Reference

Functional Block Diagram

Absolute Maximum RatingsParameter Symbol Rating Units

Cathode-Anode Reverse Breakdown VKA 37 V

Anode-Cathode Forward Current IAK 1 A

Operating Cathode Current IKA 250 mA

Reference Input Current IREF 10 mA

Continuous Power at 25¡C PDTO-92 775 mW

8L SOIC 750 mW

SOT-89 1000 mW

SOT-23/5L 200 mW

Junction Temperature TJ 150 ¡C

Storage Temperature TSTG Ð65 to 150 ¡C

Lead Temperature, Soldering 10 Seconds TL 300 ¡C

Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is astress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sec-tions of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.

Ð

+REFERENCE (R)

ANODE (A)

CATHODE (K)

2.5 V

Recommended ConditionsParameter Symbol Rating Unit

Cathode Voltage VKA VREF to 20 V

Cathode Current IK 10 mA

Typical Thermal ResistancesPackage θJA θJC Typical Derating

TO-92 160¡C/W 80¡C/W 6.3 mW/¡C

SOIC 175¡C/W 45¡C/W 5.7 mW/¡C

SOT-89 110¡C/W 8¡C/W 9.1 mW/¡C

SOT-23/5L 575¡C/W 150¡C/W 1.7 mW/¡C



Electrical CharacteristicsElectrical Characteristics are guaranteed over full junction temperature range (0 to 105¡C). Ambient temperature must be derated basedon power dissipation and package thermal characteristics. The conditions are: VKA = VREF and IK = 10 mA unless otherwise stated.

Test AS431 (0.25%) AS431 (0.5%) TestParameter Symbol Condition Min. Typ. Max. Min. Typ. Max. Unit Circuit

Reference Voltage VREF TA = 25¡C 2.496 2.503 2.509 2.490 2.503 2.515 V 1

Over temp. 2.475 2.530 2.469 2.536 V 1

ÆVREF with Temp* TC 0.07 0.20 0.07 0.20 mV/¡C 1

Ratio of Change in ÆVREF VREF to 10 V Ð2.7 Ð1.0 Ð2.7 Ð1.0VREF to Cathode ÆVK mV/V 2Voltage 10 V to 36 V Ð2.0 Ð0.4 0.3 Ð2.0 Ð0.4 0.3

Reference Input IREF 0.7 4 0.7 4 µA 2Current

IREF Temp Deviation ÆIREF Over temp. 0.4 1.2 0.4 1.2 µA 2

Min IK for Regulation IK(min) 0.4 1 0.4 1 mA 1

Off State Leakage IK(off) VREF = 0 V, 0.04 250 0.04 250 nA 3VKA = 36 V

Dynamic Output ZKA f ² 1 kHz 0.15 0.5 0.15 0.5 ½ 1Impedance IK = 1 to 150 mA



Over temp. 2.449 2.541 2.430 2.569 V 1







Dynamic Output ZKA f ² 1 kHz 0.15 0.5 0.15 0.5 ½ 1Impedance IK = 1 to 150 mA

*Calculating Average Temperature Coefficient (TC). Refer to following page.



Test Circuits

Average Temperature Coefficient

Figure 1a. Test Circuit 1 Figure 1b. Test Circuit 2 Figure 1c. Test Circuit 3

0

–10

–20

0.55000

0 0

0 15

0.07 mV/°C

0.003%/°C

27 ppm/°C

30 45 60 75 90 105

ppm mV

%∆VREF

∆T

Temperature (°C)

• TC in mV/°C =

• TC in %/°C =

∆TA

∆TA

X 100

∆VREF (mV)

VREF at 25°C

∆VREF

• TC in ppm/°C = ∆TA

X 106VREF at 25°C

∆VREF

R1

R2

IK

VIN VKA

(VREF)IREF

IREF IK

VIN VKA = VREF

IK (OFF)

VIN VKA



Typical Performance Curves

Figure 2

Figure 4

Figure 3

Figure 5

I K –

Cat

hode

Cur

rent

(µA)

900

700

600

500

400

300

200

100

0

–100

–200

800

–1.0 0 1.0

VKA – Cathode Voltage (V)

2.0 3.0

Low Current Operating Characteristics

VKA = VREFTemperature Range: –55 to 125°C

125°C

25°C

–55°C

I K –

Cat

hode

Cur

rent

(mA)

150

125

100

75

50

25

0

–25

–50

–75

–100–2 –1 0 1 2 3


High Current Operating Characteristics


I Z o

ff –

Off S

tate

Cat

hode

Cur

rent

(nA)

100

10

1

0.1

0.01–60 –30 0 30

TA – Ambient Temperature (°C)

60 90 120

Off State Leakage

VKA = 36 VVREF = 0 V

V REF

– R

efer

ence

Vol

tage

(V)

2.56

2.55

2.54

2.53

2.52

2.51

2.50

2.49

2.48–60 –30 0 30


60 90 120

VKA = VREFIK = 10 mA

Temperature Coefficient as a Function of Trim Value

VREF = 2.503 V at 25°C




Figure 6

Figure 8

Figure 7

Figure 9

3.0

2.5

2.0

1.5

1.0

0.5

0–60 –30 0 30 60 90 120

I REF

– R

efer

ence

Inpu

t Cur

rent

(µA)


Reference Input Current

R1 = 10 kΩR2 = ∞ �IK =10 mA

0

–10

–20

–30

–40

–500 3 6 9

VKA – Cathode Voltage (V)12 15 18 21 24 27 30

V REF

– C

hang

e in

Ref

eren

ce V

olta

ge (m

V)IK = 10 mA

Temperature Range: –55 to 125°C

Reference Voltage Line Regulation

125°C

–55°C

75°C

25°C

0°C

70

60

50

40

30

20

10

0 10 100 1 k

f – Frequency (Hz)

10 k 100 k

Nois

e Vo

ltage

nV/

√HZ

VKA = VREFIK = 10 mATA = 25°C

Noise Voltage

Z KA

– Dy

nam

ic Im

peda

nce

(Ω)

0.150

0.125

0.100

0.075

0.050

0.025

0.0–60 –30 0 30

TA – Free Air Temperature

60 90 120

VKA = VREFIKA = 1 to 100 mAf ≤ 1 kHz

Low Frequency Dynamic Output Impedance




Figure 10

Figure 11

100

10

1.0

Z KA

– Dy

nam

ic Im

peda

nce

(Ω)

0.1

0.011 k 10 k 100 k

f – Frequency (Hz)1 M 10 M

TA = 25°CIK = 1 to 100 mA

Dynamic Output Impedance

70

60

50

40

30

20

10

01 k 10 k 100 k 1 M 10 M


230 ΩIK

A V –

Sm

all S

igna

l Vol

tage

Gai

n (d

B)


IK = 10 mA

OUT

GND

15 k

8.25 k

9 µF

Small Signal Voltage Gain vs. Frequency



Figure 12

6

5

4

3

Inpu

t and

Out

put V

olta

ges

(V)

2

1

0

–10 1 2 3 4 5 6 7

t – Time (µs)8 9 10 11 12

Input

Output

Pulse Response

INPUTMONITOR 220 Ω

50 Ω

OUT

GND

fP = 100 kHz

Figure 13

100

90

80

70

60

50

40

30

20

10

0100 101 102 103

CL – Load Capacitance (pF)104 105 106 107

150 Ω

CL

10 K

IK

A

C

D

BTA = 25°C

Stability Boundary Conditions

StabilityRegion

I K –

Cat

hode

Cur

rent

(mA)

A: VKA = VREFB: VKA = 5 V at IK = 10 mAC: VKA = 10 V at IK = 10 mAD: VKA = 15 V at IK = 10 mA




Features¥ Temperature-compensated: 30 ppm/¡C¥ Trimmed 0.4% bandgap reference¥ Internal amplifier with 150 mA capability¥ Temperature range: Extended to Ð55

to125¡C

¥ Low frequency dynamic outputimpedance: < 150 m½

¥ Low output noise¥ Robust ESD protection

DescriptionThe AS1431 is a three-terminal adjustable shunt regulator providing ahighly accurate 0.4% bandgap reference. The adjustable shunt regulatoris ideal for a wide variety of linear applications that can be implementedusing external components to obtain adjustable currents and voltages.In the standard shunt configuration, the combination of low temperaturecoefficient (TC), sharp turn-on characteristics, low output impedance andprogrammable output voltage make this precision reference a perfectzener diode replacement.The AS1431 is characterized to operate over the full automotive tem-perature range of Ð55 to 125¡C and is now available in the SOT-23 (5L)package.

SEMICONDUCTOR



CATHODE

TO-92 (LP) SOIC (D)

ANODE

REFERENCE

CATHODE

REFERENCE

ANODE

ANODE

N/C

CATHODE

ANODE

ANODE

N/C

SOT-89 (S)SOT-23/5L (DBV)

ANODE

REFERENCE

1

2

3

4

8

7

6

5

REFERENCE

ANODE

N/C

N/C

CATHODE


Temperature Range: D = –55°C to +125°C

Bandgap Tolerance: R4 = ±0.4%

AS1431 D R4 D 7


Package Style: D DBV LP S

= SOIC= SOT-23/5L= TO-92= SOT-89










Continuous Power Dissipation at 25¡C PDTO-92 775 mW

8L SOIC 750 mW

SOT-89 1000 mW

SOT-23/5L 200 mW



Lead Temperature Soldering 10 Seconds TL 300 ¡C


Ð

+REFERENCE (R)

ANODE (A)

CATHODE (K)

2.5 V





TO-92 160¡C/W 80¡C/W 6.3 mW/¡C

SOIC 175¡C/W 45¡C/W 5.7 mW/¡C

SOT-89 110¡C/W 8¡C/W 9.1 mW/¡C

SOT-23/5L 575¡C/W 150¡C/W 1.7 mW/¡C



Electrical CharacteristicsElectrical Characteristics are guaranteed over full junction temperature range (Ð55 to 125¡C). Ambient temperature must be deratedbased on power dissipation and package thermal characteristics. The conditions are: VKA = VREF and IK = 10 mA unless otherwise stated.

Parameter Symbol Test Condition Min. Typ. Max. Unit Circuit

Reference Voltage VREF TA = 25¡C 2.490 2.500 2.510 V 1

Over temp. 2.470 2.530 V 1

ÆVREF with Temp* TC 0.06 0.16 mV/¡C 1

Ratio of Change in VREF to ÆVREF ÆVK = 3 V to 36 V Ð2 Ð1.1 mV/V 2Cathode Voltage

Reference Input Current IREF R1 = 10 k ½; R2 = ° 0.7 1.9 µA 2

IREF Temp Deviation ÆIREF Over temp. 0.4 1.2 µA 2

Min IK for Regulation IK(min) 0.4 1 mA 1

Off State Leakage IK(off) VREF = 0 V, 0.04 500 nA 3VKA = 36 V

Dynamic Output Impedance ZKA f ² 1 kHz 0.15 0.2 ½ 1IK = 1 to 100 mA

*Calculating Average Temperature Coefficient (TC)

0

–10

–20

0.55000

0 0

–55 –25 0 25 50 75 100 125

0.06 mV/°C

0.002%/°C

24 ppm/°C

ppm mV

%

∆VREF

∆T

Temperature (°C)

• TC in mV/°C =

• TC in %/°C =

∆TA

∆TA

X 100

∆VREF (mV)

VREF at 25°C

∆VREF


X 106VREF at 25°C

∆VREF




Test Circuits


R1

R2

IK

VIN VKA

(VREF)

IREF

IREF IK

VIN VKA = VREF

IK (OFF)

VIN VKA




Figure 2

Figure 4

Figure 3

Figure 5

I K –

Cat

hode

Cur

rent

(µA)

900

700

600

500

400

300

200

100

0

–100

–200

800

–1.0 0 1.0


2.0 3.0



125°C

25°C

–55°C I K –

Cat

hode

Cur

rent

(mA)

150

125

100

75

50

25

0

–25

–50

–75

–100–2 –1 0 1 2 3




I Z o

ff –

Off S

tate

Cat

hode

Cur

rent

(nA)

100

10

1

0.1

0.01–60 –30 0 30


60 90 120

Off State Leakage


V REF

– R

efer

ence

Vol

tage

(V)

2.53

2.52

2.51

2.50

2.49

2.48

2.47

2.46

2.45–60 –30 0 30


60 90 120


Reference Voltage vs Ambient Temperature

VREF = 2.500 V at 25°C




Figure 6

Figure 8

Figure 7

Figure 9

3.0

2.5

2.0

1.5

1.0

0.5

0–60 –30 0 30 60 90 120

I REF

– R

efer

ence

Inpu

t Cur

rent

(µA)



R1 = 10 kΩR2 = ∞ �IK =10 mA

0

–10

–20

–30

–40

–500 3 6 9

VKA – Cathode Voltage (V)12 15 18 21 24 27 30

V REF

– C

hang

e in

Ref

eren

ce V

olta

ge (m

V)IK = 10 mA



125°C

–55°C

75°C

25°C

0°C

70

60

50

40

30

20

10

0 10 100 1 k


10 k 100 k

Nois

e Vo

ltage

nV/

√HZ


Noise Voltage

Z KA

– Dy

nam

ic Im

peda

nce

(Ω)

0.150

0.125

0.100

0.075

0.050

0.025

0.0–60 –30 0 30


60 90 120






Figure 10

Figure 11

100

10

1.0

Z KA

– Dy

nam

ic Im

peda

nce

(Ω)

0.1

0.011 k 10 k 100 k


TA = 25°CIK = 1 to 100 mA


70

60

50

40

30

20

10

01 k 10 k 100 k 1 M 10 M


230 ΩIK

A V –

Sm

all S

igna

l Vol

tage

Gai

n (d

B)


IK = 10 mA

OUT

GND

15 k

8.25 k

9 µF




Figure 12

Figure 13

6

5

4

3

Inpu

t and

Out

put V

otag

es (V

)

2

1

0

–00 1 2 3 4 5 6 7

t – Time (ms)8 9 10 11 12

Input

Output

Pulse Response


50 Ω

OUT

GND

fp = 100 kHz

100

90

80

70

60

50

40

30

20

10

0100 101 102 103

CL – Load Capacitance (pF)104 105 106 107

150 Ω

CL

10 K

IKC

DTA = 25°C


StabilityRegionI K

– C

atho

de C

urre

nt (m

A)


A

B




Features¥ Temperature-compensated: 15 ppm/¡C

¥ Trimmed bandgap reference

¥ Internal amplifier with 100 mA capability

¥ Multiple temperature ranges

¥ Low frequency dynamic output impedance:< 450 m½

¥ Low output noise

DescriptionThe AS2431 is a three-terminal adjustable shunt regulator providing a highly accu-rate bandgap reference. The adjustable shunt regulator is ideal for a wide varietyof linear applications that can be implemented using external components toobtain adjustable currents and voltages.In the standard shunt configuration, the combination of low temperature coeffi-cient (TC), sharp turn-on characteristics, low output impedance and program-mable output voltage make this precision reference an excellent error amplifier.The AS2431 is a direct replacement for the AS431 in low voltage, low current appli-cations. It is also available in the very small footprint SOT-23.

SEMICONDUCTOR


CATHODE

TO-92 (LP) SOIC (D)

ANODE

REFERENCE

CATHODE

REFERENCE

ANODE

ANODE

N/C

CATHODE

ANODE

ANODE

N/C

SOT-89 (S)SOT-23/3L (VS)

ANODE

REFERENCE

1

2

3

4

8

7

6

5

CATHODE

REFERENCE

ANODE


Temperature Range: A = 0°C to 70°C B = 0°C to 105°C C = –40°C to +85°C D = –55°C to +125°C

Bandgap Tolerance: 2 1 R4 R5 R25

= ±2%= ±1%= ±0.4%= ±0.5%= ±0.25%

AS2431 A 2 D 7


Package Style: D LP S VS


= SOIC= TO-92= SOT-89= SOT-23/3L










Continuous Power Dissipation at 25¡C PDTO-92 775 mW

8L SOIC 750 mW

SOT-89 1000 mW

SOT-23/3L 200 mW



Lead Temp, Soldering 10 Seconds TL 300 ¡C


Ð

+REFERENCE (R)

ANODE (A)

CATHODE (K)

2.5 V





TO-92 160¡C/W 80¡C/W 6.3 mW/¡C

SOIC 175¡C/W 45¡C/W 5.7 mW/¡C

SOT-89 110¡C/W 8¡C/W 9.1 mW/¡C

SOT-23/3L 575¡C/W 150¡C/W 1.7 mW/¡C



Electrical CharacteristicsElectrical Characteristics are guaranteed over full junction temperature range (0 to 105¡C). Ambient temperature must be derated basedon power dissipation and package thermal characteristics. The conditions are: VKA = VREF and IK = 10 mA unless otherwise stated.



Over temp. 2.480 2.518 2.480 2.530 V 1







Dynamic Output ZKA f ² 1 kHz 0.45 1 0.45 1 ½ 1Impedance IK = 1 to 150 mA



Over temp. 2.450 2.540 2.415 2.580 V 1







Dynamic Output ZKA f ² 1 kHz 0.45 1 0.45 1 ½ 1Impedance IK = 1 to 150 mA

*Calculating Average Temperature Coefficient (TC). Refer to following page.



Test Circuits



0

–10

–20

0.55000

0 0

0 15

0.07 mV/°C

0.003%/°C

27 ppm/°C

30 45 60 75 90 105

ppm mV

%∆VREF

∆T

Temperature (°C)

• TC in mV/°C =

• TC in %/°C =

∆TA

∆TA

X 100

∆VREF (mV)

VREF at 25°C

∆VREF


X 106VREF at 25°C

∆VREF

R1

R2

IK

VIN VKA

(VREF)IREF

IREF IK

VIN VKA = VREF

IK (OFF)

VIN VKA



Typical Performance

Figure 2

Figure 4

Figure 3

Figure 5

I K –

Cat

hode

Cur

rent

(µA)

900

700

600

500

400

300

200

100

0

–100

–200

800

–1.0 0 1.0


2.0 3.0



125°C

25°C

–55°C I K –

Cat

hode

Cur

rent

(mA)

150

125

100

75

50

25

0

–25

–50

–75

–100–2 –1 0 1 2 3




I Z o

ff –

Off S

tate

Cat

hode

Cur

rent

(nA)

100

10

1

0.1

0.01–60 –30 0 30


60 90 120

Off State Leakage


V REF

– R

efer

ence

Vol

tage

(V)

3.53

2.52

2.51

2.50

2.49

2.48

2.47

2.46

2.45–60 –30 0 30


60 90 120



VREF = 2.500 V at 25°C




Figure 6

Figure 8

Figure 7

Figure 9

3.0

2.5

2.0

1.5

1.0

0.5

0–60 –30 0 30 60 90 120

I REF

– R

efer

ence

Inpu

t Cur

rent

(µA)



R1 = 10 kΩR2 = ∞ �IK =10 mA

0

–5

–10

–15

–20

–250 3 6 9

VKA – Cathode Voltage (V)12 15 18

∆ VRE

F – C

hang

e in

Ref

eren

ce V

olta

ge (m

V)IK = 10 mA


–30°C

25°C

75°C

125°C


70

60

50

40

30

20

10

0 10 100 1 k


10 k 100 k

Nois

e Vo

ltage

nV/

√Hz


Noise Voltage

Z KA

– Dy

nam

ic Im

peda

nce

(Ω)

0.150

0.125

0.100

0.075

0.050

0.025

0.0–60 –30 0 30


60 90 120






Figure 10

Figure 11

100

10

1.0

Z KA

– Dy

nam

ic Im

peda

nce

(Ω)

0.1

0.011 k 10 k 100 k


TA = 25°CIK = 1 to 100 mA


70

60

50

40

30

20

10

01 k 10 k 100 k 1 M 10 M


230 ΩIK

A V –

Sm

all S

igna

l Vol

tage

Gai

n (d

B)


IK = 10 mA

OUT

GND

15 k

8.25 k

9 µF





Figure 12

Figure 13

6

5

4

3

Inpu

t and

Out

put V

otag

es (V

)

2

1

0

–10 1 2 3 4 5 6 7

t – Time (ms)8 9 10 11 12

Input

Output

Pulse Response


50 Ω

OUT

GND

fP = 100 kHz

100

90

80

70

60

50

40

30

20

10

0100 101 102 103

CL – Load Capacitance (pF)

104 105 106 107

150 Ω

CL

10 K

IK

A

C

D

BTA = 25°C


StabilityRegionI K

– C

atho

de C

urre

nt (m

A)



AS4321.24V Precision Adjustable Shunt Reference/Amplifier

Features¥ Temperature-compensated:

50 ppm/¡C¥ 0.25% to 2.0% bandgap offered¥ Internal amplifier with 150 mA

capability¥ Multiple temperature ranges¥ Low frequency dynamic output

impedance: < 150 m½¥ Low output noise

DescriptionThe AS432 is a three terminal adjustable shunt regulator utilizing an accurate1.24V bandgap reference. The AS432 is functionally similar to an AS431 exceptfor its lower reference voltage, making it usable in a wide variety of low voltageapplications.

Because of its robust bipolar technology, the AS432 handles a wide range of cur-rent, and holds off more than 18V so its use is not limited to low power, low volt-age systems. Significant care has been taken to provide adequate AC bandwidthto allow the AS432 as an amplifier in control systems and power electronics.

SEMICONDUCTOR



CATHODE

TO-92 (LP) SOIC (D)

ANODE

REFERENCE

REFERENCE

ANODE

ANODE

N/C

CATHODE

ANODE

ANODE

N/C

SOT-89 (S)

CATHODE

ANODE

REFERENCE

1

2

3

4

8

7

6

5

SOT-23/5L (DBV)

ANODE

REFERENCE

N/C

N/C

CATHODE

SOT-23/3L (VS)

CATHODE

REFERENCE

ANODE

Circuit Type: 1.24V Precision Adjustable Shunt Regulator/Amplifier

Temperature Range: A B C

Bandgap Tolerance: 2 1 R5 R25

= 0°C to 70°C= 0°C to 105°C= –40°C to +85°C

= ±2%= ±1%= ±0.5%= ±0.25%


Package Style: D DBV LP S VS


= SOIC= SOT-23/5L= TO-92= SOT-89= SOT-23/3L

AS432 A 2 D 7


AS432 1.24V Precision Adjustable Shunt Reference/Amplifier


Ð

+REFERENCE (R)

ANODE (A)

CATHODE (K)

1.24 VÐ

+






Continuous Power at 25¡C PDTO-92 775 mW

8L SOIC 750 mW

SOT-89 1000 mW

SOT-23/3L/5L 200 mW



Lead Temperature (Soldering 10 sec.) TL 300 ¡C






TO-92 160¡C/W 80¡C/W 6.3 mW/¡C

SOIC 175¡C/W 45¡C/W 5.7 mW/¡C

SOT-89 110¡C/W 8¡C/W 9.1 mW/¡C

SOT-23/3L/5L 575¡C/W 150¡C/W 1.7 mW/¡C



Electrical CharacteristicsElectrical characteristics are guaranteed over the full junction temperature range (0Ð105¡C). Ambient temperature must be deratedbased upon power dissipation and package thermal characteristics. Unless otherwise stated, test conditions are: VKA = VREF andIK = 10 mA.

Test AS432 (0.25%) AS432 (0.5%)Parameter Symbol Condition Min. Typ. Max. Min. Typ. Max. Unit

Output Voltage VREF IK = 10 mA 1.237 1.240 1.243 1.234 1.240 1.246 VTJ = 25¡CVK = VREF

Line Regulation ÆVREF VKA = 1.25 to 15 V 28 50 28 50 mV

Load Regulation ÆVREF IK = 1 to 100 mA 3.9 6 3.9 6 mV

Temperature Deviation ÆVREF 0 < TJ < 105¡C 5 10 5 10 mV

Reference Input Current IREF 2.3 6 2.3 6 µA

Reference Input Current ÆIREF 0 < TJ < 105¡C 0.14 0.6 0.14 0.6 µATemperature Coefficient

Minimum Cathode IK(min) 0.2 1 0.2 1 mACurrent for Regulation

Off State Leakage IK(min) VREF = 0 V, 0.04 500 0.04 500 nAVKA = 15 V

Test AS432 (1.0%) AS432 (2.0%)Parameter Symbol Condition Min. Typ. Max. Min. Typ. Max. Unit

Output Voltage VREF IK = 10 mA 1.228 1.240 1.252 1.215 1.240 1.256 VTJ = 25¡CVK = VREF

Line Regulation ÆVREF VKA = 1.25 to 15 V 28 50 28 50 mV

Load Regulation ÆVREF IK = 1 to 100 mA 3.9 6 3.9 6 mV

Temperature Deviation ÆVREF 0 < TJ < 105¡C 5 12 5 12 mV

Reference Input Current IREF 2.3 6 2.3 6 µA

Reference Input Current ÆIREF 0 < TJ < 105¡C 0.14 0.6 0.14 0.6 µATemperature Coefficient

Minimum Cathode IK(min) 0.2 1 0.2 1 mACurrent for Regulation

Off State Leakage IK(min) VREF = 0 V, 0.04 500 0.04 500 nAVKA = 15 V

*Temperature deviation is defined as the maximum deviation of the reference over the given temperature range and does not implyan incremental deviation at any given temperature.



Test Circuits


R1

R2

IK

VIN VKA

(VREF)IREF

IREF IK

VIN VKA = VREF

IK (OFF)

VIN VKA

Typical Performance Curves*Calculating Average Temperature Coefficient (TC)

0

–5

–10

0.22000

0 0

0 15

0.021 mV/°C

0.008%/°C

8.0 ppm/°C

30 45 60 75 90 105

ppm mV

%∆VREF

∆T

Temperature (°C)

• TC in mV/°C =

• TC in %/°C =

∆TA

∆TA

X 100

∆VREF (mV)

VREF at 25°C

∆VREF


X 106VREF at 25°C

∆VREF



Typical Performance

Figure 2

Figure 4

Figure 3

Figure 5


I K –

Cat

hode

Cur

rent

(µA)

–0.5 0 0.5 1.0 1.5–200

–100

0

100

200

300

400

500

600

700

800

900


–55°C

25°C

125°C I K –

Cat

hode

Cur

rent

(mA)


–2 –1 0 1 2–100

–75

–50

–25

0

25

50

75

100

125

150

175


VKA = VREFTemperature Range –55 to 125°C

–60 –30 0 30


60 90 120

I Z o

ff –

Off S

tate

Cat

hode

Cur

rent

(nA)

100

10

1

0.1

0.01

Off State Leakage


–60 –30 0 30


60 90 120

V REF

– R

efer

ence

Vol

tage

(V)

1.27

1.26

1.25

1.24

1.23

1.22

1.21

1.20

1.19



VREF = 1.240 V at 25°C




Figure 6

Figure 8

Figure 7

Figure 9

–60 –30 0 30


60 90 120

I REF

– R

efer

ence

Inpu

t Cur

rent

(µA)

2.4

2.3

2.2

2.1

2.0


R1 = 10 kΩR2 = ∞IK = 10 mA

0 3 6 9 12 15 18

–40°C

25°C

75°C

125°C


∆VRE

F – C

hang

e in

Ref

eren

ce V

olta

ge (m

V)

0

–10

–20

–30

–40

–50


IK = 10 mATemperature Range: –55 to 125°C

10 100 1 k 10 k 100 k


70

60

50

40

30

20

10

0

Nois

e Vo

ltage

nV/

√Hz

Noise Voltage


–60 –30 0 30

TA – Free Air Temperature (°C)

60 90 120

40

30

20

10

0

Z KA

– Dy

nam

ic Im

peda

nce

(mΩ

)


VKA = VREFVKA = 1 to 100 mAf ≤ 1kHz




Figure 10

Figure 11

100

10

1.0

Z KA

– Dy

nam

ic Im

peda

nce

(Ω)

0.1

0.011 k 10 k 100 k


TA = 25°CIK = 1 to 100 mA


80

70

60

50

40

30

20

10

01 k 10 k 100 k 1 M 10 M


230 ΩIK

A V –

Sm

all S

igna

l Vol

tage

Gai

n (d

B)

Temperature Range: –55° to 125°C

IK = 10 mA

OUT

GND

15 k

8.25 k

9 µF





Figure 12

Figure 13

4

3

Inpu

t and

Out

put V

otag

es (V

)

2

1

0

–10 1 2 3 4 5 6 7

t – Time (µs)8 9 10 11 12

Input

Output

Pulse Response


50 Ω

OUT

GND

fP = 100 kHz

100

90

80

70

60

50

40

30

20

10

0100 101 102 103

CL – Load Capacitance (pF)

104 105 106 107

150 Ω

CL

10 K

IK

A

C

D

BTA = 25°C


StabilityRegionI K

– C

atho

de C

urre

nt (m

A)


AS1004Micropower Voltage Reference

DescriptionThe AS1004 is a two-terminal precision band-gap voltagereference with a low turn-on current of 10 µA.

Emulating a 1.235 V zener diode, the AS1004 operates morethan three orders of magnitude of output current with minuteoutput impedance and guaranteed stability. With an initialtolerance of ± 4 mV and guaranteed temperature perfor-mance, it is ideal for precision instrumentation, especially inlow power applications. Being a low-voltage reference, theAS1004 is also well-suited as a reference for low-voltagepower supply applications, especially in power suppliesintended for low-voltage logic systems, laptop computersand other portable or battery operated equipment.

The AS1004 is pin-for-pin compatible with the LT1004 andthe LM385 and offers improved specifications over both theLM385 and the MP5010. It is also available as a 2.5 Vreference with a guaranteed start-up current of 20 µA.

Features

• Low voltage reference• 10 µA turn-on current for

AS1004-1.2

• 20 µA turn-on current forAS1004-2.5

• ± 4 mV (0.3 %) initial accuracyfor AS1004-1.2

• ± 20 mV (0.8 %) initial accuracyfor AS1004-2.5

• Guaranteed operation to 20 mA.Over three orders of magnitudeof operating current!

• Temperature performanceguaranteed

• Very low dynamic impedance


Description Temperature Range Order Codes

TO-92 0 to 70° C AS1004-1.2LP AS1004-2.5LP

8-Pin Plastic SOIC 0 to 70° C AS1004-1.2D AS1004-2.5D

SOT-89 0 to 70° C AS1004-1.2S AS1004-2.5S

© ASTEC Semiconductor

Pin Configuration — Top view

ANODE

CATHODE

N/C

81N/C CATHODE

72N/C N/C

63N/C CATHODE

54ANODE ANODE

N/C

ANODE

CATHODE

TO-92 (LP) SOIC (D) SOT-89 (S)

29

AS1004 Micropower Voltage Reference

ASTEC Semiconductor30

Simplified Schematic

Recommended Conditions

Parameter Symbol Rating Unit

Cathode Current IZ 100 µA

Typical Thermal Resistances

Package θJA θJC Typical Derating

TO-92 160° C/W 80° C/W 6.3 mW/°C

8L SOIC 175° C/W 45° C/W 5.7 mW/°C

SOT-89 110° C/W 8° C/W 9.1 mW/°C

Absolute Maximum Ratings

Parameter Symbol Rating Units

Reverse Breakdown Current IZ 30 mA

Forward Current IF 30 mA

Continuous Power Dissipation at 25° C PDTO-92 775 mW

8LSOIC 750 mW

SOT-89 1000 mW

Maximum Junction Temp TJ 150 °C

Storage Temperature TSTG –65 to 150 °C

Lead Temperature, Soldering 10 Seconds TL 300 °C

R2

R6 R7

C1

C2

Q12

R4

C3

R11

R10

R12

Q6

A

K

Q14

Q4 Q3Q13

Q11

Q10

Q7

Q9 Q8

Q5 Q1

Micropower Voltage Reference AS1004


Electrical CharacteristicsElectrical Characteristics are guaranteed over full junction temperature range (0 to 70° C). Ambient temperature must be derated basedon power dissipation and package thermal characteristics.

AS1004-1.2 AS1004-2.5Parameter Symbol Test Condition Min Typ Max Min Typ Max Unit

Reverse Breakdown Voltage VZ IZ = 100 µA, TJ = 25° C 1.231 1.235 1.239 2.480 2.500 2.520 V

0° C ≤ TA ≤ 70° C 1.225 1.235 1.245 2.470 2.500 2.530 V

Average Temperature ∆VZ /∆T Imin ≤ IZ ≤ 20 mA 20 60 ppm/°CCoefficient

Minimum Operating Current IZ (min) 4 10 12 20 µA

Reverse Breakdown Voltage ∆VZ /∆IZ Imin ≤ IZ ≤ 1 mA 0.5 1 0.5 1 mVChange With Current

Over Temperature 0.5 1.5 0.5 1.5 mV

1 mA ≤ IZ ≤ 20 mA 6.5 10 6.5 10 mV

Over Temperature 6.5 20 6.5 20 mV

Reverse Dynamic Impedance ZZ IZ = 100 mA, f = 25 Hz 0.2 0.6 0.8 0.9 Ω

Over Temperature 1 1.5 1.5 Ω

Wide Band Noise en IZ = 100 µA10 Hz ≤ f ≤ 10 KHz 60 60 µV

Long Term Stability ∆VZ /∆T IZ = 100 µATA = 25° C ± 0.1° C 20 60 ppm/kH

AS1004-1.2 Reference Voltage vs.Ambient Temperature

Figure 1 Figure 2


ppm

% mV

5000 0.5

0 0

0

0∆VREF

∆T

-5

-1010 20 30 40 50 60 70

Temperature (°C)

0.025 mV/°C

0.002 %/°C

20 ppm/°C

Average Temperature Coefficient =∆VREF

∆T

Calculating Average TemperatureCoefficient for the AS1004-1.2 Reference


VZ –

Ref

eren

ce V

olta

ge (

V)

1.225

1.230

1.235

1.240

1.245

–55 –15 25 85 125 –35 5 45 65 105

IZ = 100 µA




AS1004-2.5 Reference Voltageversus Ambient Temperature

Figure 3 Figure 4

AS1004-1.2 Reverse OperatingCharacteristics

AS1004-2.5 Reverse OperatingCharacteristics

Figure 5 Figure 6

VR – Reverse Voltage (V)

IR –

Rev

erse

Cur

rent

(µA

)

1

10

100

0.1 0 0.2 0.6 1 1.4 0.4 0.8 1.2

TA = –55° C to 125° C

VR – Reverse Voltage (V)

I R –

Rev

erse

Cur

rent

(µA

)

1

10

100

0.1 0 0.5 1.5 2.0 3.0 1.0 2.5

TA = –55° C to 125° C

ppm

% mV

5000 0.5

0 0

0

0∆VREF

∆T

-5

-1010 20 30 40 50 60 70

Temperature (°C)

0.046 mV/°C

0.004 %/°C

37 ppm/°C

Average Temperature Coefficient =∆VREF

∆T

Calculating Average TemperatureCoefficient for the AS1004-2.5 Reference


VZ –

Ref

eren

ce V

olta

ge (

V)

2.480

2.490

2.500

2.510

2.520

–55 –15 25 85 125 –35 5 45 65 105

IZ = 100 µA




AS1004-1.2 Change in ReferenceVoltage versus Reverse Current

AS1004-2.5 Change in ReferenceVoltage versus Reverse Current

Figure 9

Figure 7 Figure 8

IR – Reverse Current (mA)

∆V

Z –

Cha

nge

In R

efer

ence

Vol

tage

(m

A)

0

4

8

12

16

–4 0.01 0.1 1 10 100

TA = –55° C to 125° C

Figure 10

AS1004-1.2 Transient Response AS1004-2.5 Transient Response

IR – Reverse Current (mA)

∆V

Z –

Cha

nge

In R

efer

ence

Vol

tage

(m

A)

0

4

8

12

16

–4 0.01 0.1 1 10 100

TA = –55° C to 125° C

t – Time (µs)

Inpu

t and

Out

put V

olta

ge (

V)

5

0.5

1.5

00 50 100 600 500

INPUT

1

0

OUTPUT

VO

36 kΩVI

t – Time (µs)

Inpu

t and

Out

put V

olta

ge (

V)

5

1

3

00 50 100 600 500

VO36 kΩ

VI

INPUT

2

0

OUTPUT




Figure 11 Figure 12

Figure 13 Figure 14

AS1004-1.2 Reverse DynamicImpedance

AS1004-2.5 Reverse DynamicImpedance

Low Frequency Reverse DynamicImpedance

f = Frequency (kHz)

ZZ –

Ref

eren

ce Im

peda

nce

(Ω)

1

10

100

1 k

10 k

0.1 0.01 0.1 1 10 1 k 100

tZ = 100 µA TA = 25° C

f = Frequency (kHz)

ZZ –

Ref

eren

ce Im

peda

nce

(Ω)

1

10

100

1 k

10 k

0.1 0.01 0.1 1 10 1 k 100

tZ = 100 µA TA = 25° C

Forward Characteristics

IF = Forward Current (mA)

VF –

For

war

d V

olta

ge (

V)

0.4

0.8

1.2

0 0.01 0.1 1 10 100

TA = 25° C

IZ – Reverse Current (mA)

ZZ –

Ref

eren

ce Im

peda

nce

(Ω)

1

10

100

0.1 0.01 0.1 1 10 100

TA = –55° C to 125° C f = 25 Hz



Typical Applications

2.5V Reference

VIN

3 k

OUT

AS1004-1.2

VIN

100 k

OUT

AS1004-2.5

VIN

100 k

OUT

AS1004-2.5

22 Ω

50 µF

Low Noise Reference1.235V Reference

Figure 20 Figure 21

Figure 15 Figure 16 Figure 17

High Stability 5V Regulator

VIN

OUT

AS1004-2.5

200 Ω

10 µF

0.1 µF +

5 k

V-

LM317VIN VOUT

ADJ

R ≤ V-– 1V

0.015 mA

Variable OutputRegulator

Figure 18 Figure 19

Lead Acid Low Battery Detector

–

+12 V

86.7 k

500 k 150 pF

AS1004-1.2

500 kLO = Battery Low

Micropower 10V Reference

VIN ≥ 8 V

5 V OUT

AS1004-2.5

976 Ω, 1%

22 µF

+

LM338VIN VOUT

ADJ

324 Ω, 1%

22 M

1 M

150 pF

AS1004-1.2

–

+

3.5 M

500 k

LM4250

3

2

7

68

4

VIN = 12 V to 20 V

AS2842/3/4/5Current Mode Controller

DescriptionThe AS2842 family of control ICs provide pin-for-pin replace-ment of the industry standard UC3842 series of devices. Thedevices are redesigned to provide significantly improvedtolerances in power supply manufacturing. The 2.5 V refer-ence has been trimmed to 1.0% tolerance. The oscillatordischarge current is trimmed to provide guaranteed dutycycle clamping rather than specified discharge current. Thecircuit is more completely specified to guarantee all param-eters impacting power supply manufacturing tolerances.

In addition, the oscillator and flip-flop sections have beenenhanced to provide additional performance. The RT/CT pinnow doubles as a synchronization input that can be easilydriven from open collector/open drain logic outputs. Thissync input is a high impedance input and can easily be usedfor externally clocked systems. The new flip-flop topologyallows the duty cycle on the AS2844/5 to be guaranteedbetween 49 and 50%. The AS2843/5 requires less than0.5 mA of start-up current over the full temperature range.

Pin Configuration — Top view

Features

• 2.5 V bandgap referencetrimmed to 1.0% andtemperature-compensated

• Extended temperature rangefrom - 40 to 105° C

• AS2842/3 oscillations trimmedfor precision duty cycle clamp

• AS2844/5 have exact 50% maxduty cycle clamp

• Advanced oscillator designsimplifies synchronization

• Improved specs on UVLOand hysteresis providemore predictable start-upand shutdown

• Improved 5 V regulator providesbetter AC noise immunity

• Guaranteed performancewith current sense pulledbelow ground

• Over-temperature shutdown

8L SOIC (D)

81COMP VREG

72VFB VCC

63ISENSE OUT

54RT/CT GND

PDIP (N)

81COMP VREG

72VFB VCC

63ISENSE OUT

54RT/CT GND


Description Temperature Range Order Codes

8-Pin Plastic DIP -40 to 105° C AS2842/3/4/5N8-Pin Plastic SOIC -40 to 105° C AS2842/3/4/5D-8

ASTEC Semiconductor

37

AS2842/3/4/5 Current Mode Controller



Pin Function Description

Pin Number Function Description

1 COMP This pin is the error amplifier output. Typically used to provide loop compensation tomaintain VFB at 2.5 V.

2 VFB Inverting input of the error amplifier. The non-inverting input is a trimmed 2.5 Vbandgap reference.

3 ISENSE A voltage proportional to inductor current is connected to the input. The PWM usesthis information to terminate the gate drive of the output.

4 RT/CT Oscillator frequency and maximum output duty cycle are set by connecting a resistor(RT) to VREG and a capacitor (CT) to ground. Pulling this pin to ground or to VREG willaccomplish a synchronization function.

5 GND Circuit common ground, power ground, and IC substrate.

6 OUT This output is designed to directly drive a power MOSFET switch. This output can sinkor source peak currents up to 1A. The output for the AS2844/5 switches at one-half theoscillator frequency.

7 VCC Positive supply voltage for the IC.

8 VREG This 5 V regulated output provides charging current for the capacitor CT through theresistor RT.

Figure 1. Block Diagram of the AS2842/3/4/5

–

+

–

+

–

+

–

+

6OUT

2

ERROR AMP

1

4 5

7

8

GND

VCC

VREG

RT/CT

VFB

COMP

S

R

FF

S

R

FF

(5.0 V)

(2.5 V)

(1.0 V)

2R

R

(5 V)

(3.0 V)

(1.3 V)

(0.6 V)OSCILLATOR

PWMCOMPARATOR

OVERTEMPERATURE

T

FF

CLK ÷ 2 [3844/45]

CLK [3842/43]

5 VREGULATOR

(5.0 V)

REF OK

(4 V)

UVLO

(4 V)

PWM LOGIC

3

+

–

ISENSE

ASTEC Semiconductor

Current Mode Controller AS2842/3/4/5

39

Absolute Maximum Ratings


Supply Voltage (ICC < 30 mA) VCC Self-Limiting V

Supply Voltage (Low Impedance Source) VCC 30 V

Output Current IOUT ±1 AOutput Energy (Capacitive Load) 5 µJAnalog Inputs (Pin 2, Pin 3) –0.3 to 30 V

Error Amp Sink Current 10 mA

Maximum Power Dissipation PD8L SOIC 750 mW8L PDIP 1000 mW

Maximum Junction Temperature TJ 150 °CStorage Temperature Range TSTG – 65 to 150 °CLead Temperature, Soldering 10 Seconds TL 300 °CStresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stressrating only and functional operation of the device at these or any other conditions above indicated in the operational sections of thisspecification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.

Recommended Conditions


Supply Voltage VCCAS2842,4 15 V

AS2843,5 10 V

Oscillator fOSC 50 to 500 kHz

Typical Thermal Resistances

Package θJA θJC Typical Derating

8L PDIP 95° C/W 50° C/W 10.5 mW/°C8L SOIC 175° C/W 45° C/W 5.7 mW/°C



Electrical CharacteristicsElectrical characteristics are guaranteed over full junction temperature range (-40 to 105° C ). Ambient temperature must be derated basedon power dissipation and package thermal characteristics. The conditions are: VCC = 15 V, RT = 10 kΩ, and CT = 3.3 nF, unless otherwisestated. To override UVLO, VCC should be raised above 17 V prior to test.

Parameter Symbol Test Condition Min Typ Max Unit

5 V Regulator

Output Voltage VREG TJ = 25° C, IREG = 1 mA 4.95 5.00 5.05 V

Line Regulation PSRR 12 ≤ VCC ≤ 25 V 2 10 mV

Load Regulation 1 ≤ IREG ≤ 20 mA 2 10 mV

Temperature Stability1 TCREG 0.2 0.4 mV/°C

Total Output Variation1 Line, load, temperature 4.85 5.15 V

Long-term Stability1 Over 1,000 hrs at 25° C 5 25 mV

Output Noise Voltage VNOISE 10 Hz ≤ f ≤ 100 kHz, TJ = 25° C 50 µV

Short Circuit Current ISC 30 100 180 mA

2.5 V Internal Reference

Nominal Voltage VFB T = 25° C; IREG = 1 mA 2.475 2.500 2.525 V

Line Regulation PSRR 12 V ≤ VCC ≤ 25 V 2 5 mV

Load Regulation 1 ≤ IREG ≤ 20 mA 2 5 mV

Temperature Stability1 TCVFB 0.1 0.2 mV/°C

Total Output Variation1 Line, load, temperature 2.450 2.500 2.550 V

Long-term Stability1 Over 1,000 hrs at 125° C 2 12 mV

Oscillator

Initial Accuracy fOSC TJ = 25° C 47 52 57 kHz

Voltage Stability 12 V ≤ VCC ≤ 25 V 0.2 1 %

Temperature Stability1 TCf TMIN ≤ TJ≤ TMAX 5 %

Amplitude fOSC VRT/CT peak-to-peak 1.6 V

Upper Trip Point VH 2.9 V

Lower Trip Point VL 1.3 V

Sync Threshold VSYNC 400 600 800 mV

Discharge Current ID 7.5 8.7 9.5 mA

Duty Cycle Limit RT = 680 Ω, CT = 5.3 nF, TJ = 25° C 46 50 52 %

ASTEC Semiconductor


41

Electrical Characteristics (cont’d)Electrical characteristics are guaranteed over full junction temperature range (-40 to 105° C ). Ambient temperature must be derated basedon power dissipation and package thermal characteristics. The conditions are: VCC = 15 V, RT = 10 kΩ, and CT = 3.3 nF, unless otherwise stated.To override UVLO, VCC should be raised above 17 V prior to test.


Error Amplifier

Input Voltage VFB TJ = 25° C 2.475 2.50 2.525 V

Input Bias Current IBIAS – 0.1 –1 µA

Voltage Gain AVOL 2 ≤ VCOMP ≤ 4 V 65 90 dB

Transconductance Gm 1 mA/mV

Unity Gain Bandwidth1 GBW 0.8 1.2 MHz

Power Supply Rejection Ratio PSRR 12 ≤ VCC ≤ 25 V 60 70 dB

Output Sink Current ICOMPL VFB = 2.7 V, VCOMP = 1.1V 2 6 mA

Output Source Current ICOMPH VFB = 2.3 V, VCOMP = 5 V 0.5 0.8 mA

Output Swing High VCOMPH VFB = 2.3 V, RL = 15 kΩ to Ground 5 5.5 V

Output Swing Low VCOMPL VFB = 2.7 V, RL = 15 kΩ to Pin 8 0.7 1.1 V

Current Sense Comparator

Transfer Gain2,3 AVCS –0.2 ≤ VSENSE ≤ 0.8 V 2.85 3.0 3.15 V/V

ISENSE Level Shift2 VLS VSENSE = 0 V 1.5 V

Maximum Input Signal2 VCOMP = 5 V 0.9 1 1.1 V

Power Supply Rejection Ratio PSRR 12 ≤ VCC ≤ 25 V 70 dB

Input Bias Current IBIAS –1 –10 µA

Propagation Delay to Output1 tPD 85 150 ns

Output

Output Low Level VOL ISINK = 20 mA 0.1 0.4 V

VOL ISINK = 200 mA 1.5 2.2 V

Output High Level VOH ISOURCE = 20mA 13 13.5 V

VOH ISOURCE = 200mA 12 13.5 V

Rise Time1 tR CL = 1 nF 50 150 ns

Fall Time1 tF CL = 1 nF 50 150 ns

Housekeeping

Start-up Threshold VCC(on) 2842/4 15 16 17 V

2843/5 7.8 8.4 9.0 V

Minimum Operating Voltage VCC(min) 2842/4 9 10 11 V

After Turn On 2843/5 7.0 7.6 8.2 V

Output Low Level in UV State VOUV ISINK = 20 mA, VCC = 6 V 1.5 2.0 V

Over-Temperature Shutdown4 TOT 125 °C



Notes:1. This parameter is not 100% tested in production.2. Parameter measured at trip point of PWM latch.3. Transfer gain is the relationship between current sense input and corresponding error amplifier output at the PWM latch trip pointand is mathematically expressed as follows:

4. At the over-temperature threshold, TOT, the oscillator is disabled. The 5 V reference and the PWM stages, including the PWMlatch, remain powered.

Electrical Characteristics (cont’d)Electrical characteristics are guaranteed over full junction temperature range (-40 to 105° C ). Ambient temperature must be derated basedon power dissipation and package thermal characteristics. The conditions are: VCC = 15 V, RT = 10 kΩ, and CT = 3.3 nF, unless otherwise stated.To override UVLO, VCC should be raised above 17 V prior to test.


AI

VVCOMP

SENSE

= − ≤ ≤∆∆

; 0.2 V 0.8SENSE

PWM

Maximum Duty Cycle Dmax 2842/3 94 97 100 %

Minimum Duty Cycle Dmin 2842/3 0 %

Maximum Duty Cycle Dmax 2844/5 49 49.5 50 %

Minimum Duty Cycle Dmin 2844/5 0 %

Supply Current

Start-up Current ICC 2842/4, VFB = VSENSE = 0 V, VCC = 14 V 0.5 1.0 mA2843/5, VFB = VSENSE = 0 V, VCC = 7 V 0.3 0.5 mA

Operating Supply Current ICC 9 17 mA

VCC Zener Voltage VZ ICC = 25 mA 30 V

ASTEC Semiconductor


43


Supply Current vs Supply Voltage Output Voltage vs Supply Voltage

Regulator Output Voltage vsAmbient Temperature

Regulator Short Circuit Current vsAmbient Temperature

Figure 2 Figure 3

Figure 4 Figure 5

TA – Ambient Temperature (°C)–60

I RE

G –

Reg

ulat

or S

hort

Circ

uit (

mA

)

40

60

100

120

140

180

0 30 90 150–30 60 120

80


4.90

VR

EG –

Reg

ulat

or O

utpu

t (V

)

4.92

4.94

4.98

5.00

5.02

5.04

0 30 90 150–30 60 120

4.96

VCC – Supply Voltage (V)0

0

I CC –

Sup

ply

Cur

rent

(m

A)

10

15

20

25

10 15 25

5

5 20 35

AS

2842

/4

AS

2843

/5

30VCC – Supply Voltage (V)

00

VO

UT –

Out

put V

olta

ge (

V)

10

15

20

25

10 15 25

5

5 20 30

AS

2843

/5

AS

2842

/4




Regulator Load Regulation

Timing Capacitor vs OscillatorFrequency

Figure 6 Figure 7

Figure 8 Figure 9

Maximum Duty Cycle TemperatureStability

Maximum Duty Cycle vs TimingResistor

ISC – Regulator Source Current (mA)0

∆VR

EG –

Reg

ulat

or V

olta

ge C

hang

e (m

V)

–24

–20

–12

–8

–4

0

40 60 100 14020 80

–16

120

150° C 25° C –55° C

RT – Timing Register (kΩ)0.3

20

Max

imum

Dut

y C

ycle

(%

)40

60

80

100

101 3

FOSC – Oscillator Frequency (kHz)10

0.1

CT –

Tim

ing

Cap

acito

r (n

F)

1

10

100

100 1 M

RT = 1 kΩ

RT = 680 Ω

RT = 4.7 kΩ

RT = 10 kΩ

RT = 2.2 kΩ

TA – Ambient Temperature–55

40

Max

imum

Dut

y C

ycle

(%

)

60

80

100

45 125

50

70

90

–35 –15 5 25 65 85 105

RT = 1 kΩ

RT = 680 Ω

RT = 10 kΩ

RT = 2.2 kΩ

ASTEC Semiconductor


45


Current Sense Input Threshold vsError Amp Output Voltage

Error Amp Input Voltage vs AmbientTemperature

Output Sink Capability In Under-Voltage Mode Output Saturation Voltage

Figure 10 Figure 11

Figure 12 Figure 13


2.460

VF

B –

Err

or A

mp

Inpu

t Vol

tage

(V

)2.470

2.480

2.490

2.500

2.510

0 30 90 150–30 60 120

VFB = VCOMPVCC = 15 V

VCOMP – Error Amp Output Voltage (V)0

–0.4

VS

EN

SE –

Cur

rent

Sen

se In

put T

hres

hold

(V

)

–0.2

0.2

0.4

0.6

1.2

1 3 5 62 4

0

0.8

1.0

TA = –55° C

TA = 25° C

TA = 125° C

VOUT – Output Voltage (V)0

1

I OU

T –

Out

put S

ink

Cur

rent

(m

A)

10

100

1 A

1.5 2.50.5 1 2

VCC = 6 VTA = 25° C

IOUT – Output Saturation Current (mA)10

0

VS

AT –

Out

put S

atur

atio

n V

olta

ge (

V)

3

–1

0

100 500

–2

2

1 Sink SaturationTJ = 125° C

TJ = –55° C

TJ = 25° C

TJ = 125° CSource Saturation

VOUT – VCC



Application InformationThe AS2842/3/4/5 family of current-mode controlICs are low cost, high performance controllerswhich are pin compatible with the industrystandard UC2842 series of devices. Suitable formany switch mode power supply applications,these ICs have been optimized for use in highfrequency off-line and DC-DC converters.The AS2842 has been enhanced to providesignificantly improved performance, resulting inexceptionally better tolerances in power supplymanufacturing. In addition, all electrical charac-teristics are guaranteed over the full 0 to 105 °Ctemperature range. Among the many enhance-ments are: a precision trimmed 2.5 volt refer-ence (±0.5% of nominal at the error amplifierinput), a significantly reduced propagation delayfrom current sense input to the IC output, atrimmed oscillator for precise duty-cycle clamp-ing, a modified flip-flop scheme that gives a true50% duty ratio clamp on 2844/45 types, andan improved 5 V regulator for better AC noiseimmunity. Furthermore, the AS2842 providesguaranteed performance with current senseinput below ground. The advanced oscillatordesign greatly simplifies synchronization. Thedevice is more completely specified to guaranteeall parameters that impact power supplymanufacturing tolerances.

Section 1— Theory of Operation

The functional block diagram of the AS2842 isshown in Figure 1. The IC is comprised of thesix basic functions necessary to implementcurrent mode control; the under voltage lockout;the reference; the oscillator; the error amplifier;the current sense comparator/PWM latch;and the output. The following paragraphs willdescribe the theory of operation of each of thefunctional blocks.

1.1 Undervoltage lockout (UVLO)

The undervoltage lockout function of the AS2842holds the IC in a low quiescent current (≤ 1 mA)“standby” mode until the supply voltage (VCC)exceeds the upper UVLO threshold voltage. Thisguarantees that all of the IC’s internal circuitryare properly biased and fully functional beforethe output stage is enabled. Once the IC turns on,the UVLO threshold shifts to a lower level (hys-teresis) to prevent VCC oscillations.

The low quiescent current standby mode of theAS2842 allows “bootstrapping” — a techniqueused in off-line converters to start the IC from therectified AC line voltage initially, after which powerto the IC is provided by an auxiliary winding offthe power supply’s main transformer. Figure 14shows a typical bootstrap circuit where capacitor

Figure 14. Bootstrap Circuit

+

R < VDC MIN1 mA

R

+C

>1 mA

16 V/10 V (2842/4)

8.4 V/7.8 V (2843/5)

OUT6

IC ENABLEAC LINE

AS284x

7 VCC

5GND

AUX

PRI SEC

VDC

ASTEC Semiconductor


47

(C) is charged via resistor (R) from the rectifiedAC line. When the voltage on the capacitor (VCC)reaches the upper UVLO threshold, the IC (andhence, the power supply) turns on and the volt-age on C begins to quickly discharge due to theincreased operating current. During this time, theauxiliary winding begins to supply the currentnecessary to run the IC. The capacitor must besufficiently large to maintain a voltage greaterthan the lower UVLO threshold during start up.The value of R must be selected to providegreater than 1 mA of current at the minimum DCbus voltage (R < VDCmin/1 mA).

The UVLO feature of the AS2842 has significantadvantages over standard 2842 devices. First,the UVLO thresholds are based on a tempera-ture compensated band gap reference ratherthan conventional zeners. Second, the UVLOdisables the output at power down, offering addi-tional protection in cases where VREG is heavilydecoupled. The UVLO on some 2842 devicesshuts down the 5 volt regulator only, whichresults in eventual power down of the output onlyafter the 5 volt rail collapses. This can lead tounwanted stresses on the switching devices dur-ing power down. The AS2842 has two separatecomparators which monitor both VCC and VREFand hold the output low if either are not withinspecification.

The AS2842 family offers two different UVLOoptions. The AS2842/4 has UVLO thresholds of16 volts (on) and 10 volts (off). The AS2843/5 hasUVLO levels of 8.4 volts (on) and 7.6 volts (off).

1.2 Reference (V REG and V FB)

The AS2842 effectively has two precise bandgap based temperature compensated voltagereferences. Most obvious is the VREG pin (pin 8)which is the output of a series pass regulator.This 5.0 V output is normally used to providecharging current to the oscillator’s timingcapacitor (Section 1.3). In addition, there is a

trimmed internal 2.5 V reference which is con-nected to the non-inverting (+) input of the erroramplifier. The tolerance of the internal referenceis ±0.5% over the full specified temperature range,and ±1% for VREG.

The reference section of the AS2842 is greatlyimproved over the standard 2842 in a number ofways. For example, in a closed loop system, thevoltage at the error amplifier’s inverting input(VFB, pin 1) is forced by the loop to match thevoltage at the non-inverting input. Thus, VFB isthe voltage which sets the accuracy of the entiresystem. The 2.5 V reference of the AS2842 istightly trimmed for precision at VFB, includingerrors caused by the op amp, and is specifiedover temperature. This method of trim provides aprecise reference voltage for the error amplifierwhile maintaining the original 5 V regulator speci-fications. In addition, force/sense (Kelvin) bond-ing to the package pin is utilized to further im-prove the 5 V load regulation. Standard 2842’s,on the other hand, specify tight regulation for the5 V output only and rate it over line, load andtemperature. The voltage at VFB, which is ofcritical importance, is loosely specified and onlyat 25° C.

The reference section, in addition to providing aprecise DC reference voltage, also powers mostof the IC’s internal circuitry. Switching noise,therefore, can be internally coupled onto thereference. With this in mind, all of the logic withinthe AS2842 was designed with ECL type circuitrywhich generates less switching noise because itruns at essentially constant current regardless oflogic state. This, together with improved ACnoise rejection, results in substantially less switch-ing noise on the 5 V output.

The reference output is short circuit protectedand can safely deliver more than 20 mA to powerexternal circuitry.



1.3 Oscillator

The newly designed oscillator of the AS2842 isenhanced to give significantly improved perfor-mance. These enhancements are discussed inthe following paragraphs. The basic operation ofthe oscillator is as follows:

A simple RC network is used to program thefrequency and the maximum duty ratio of theAS2842 output. See Figure 15. Timing capacitor(CT) is charged through timing resistor (RT) fromthe fixed 5.0 V at VREG. During the charging time,the OUT (pin 6) is high. Assuming that the outputis not terminated by the PWM latch, when thevoltage across CT reaches the upper oscillatortrip point (≈3.0 V), an internal current sink frompin 4 to ground is turned on and discharges CTtowards the lower trip point. During this dis-charge time, an internal clock pulse blanks theoutput to its low state. When the voltage acrossCT reaches the lower trip point (≈1.3 V), thecurrent sink is turned off, the output goes high,and the cycle repeats. Since the output is blankedduring the discharge of CT, it is the discharge timewhich controls the output deadtime and hence,the maximum duty ratio.

Figure 15. Oscillator Set-up and Waveforms

The nature of the AS2842 oscillator circuit is suchthat, for a given frequency, many combinations ofRT and CT are possible. However, only one valueof RT will yield the desired maximum duty ratio ata given frequency. Since a precise maximumduty ratio clamp is critical for many power supplydesigns, the oscillator discharge current istrimmed in a unique manner which providessignificantly improved tolerances as explainedlater in this section. In addition, the AS2844/5options have an internal flip-flop which effectivelyblanks every other output pulse (the oscillatorruns at twice the output frequency), providing anabsolute maximum 50% duty ratio regardless ofdischarge time.

1.3.1 Selecting timing components R T andCTThe values of RT and CT can be determinedmathematically by the following expressions:

5 V REG

OSCILLATOR

AS2842

6 OUTPUT

7 VCC

8

RT

CT

ID

5 GND

CLOCK

PWM

CT

OUTPUT

Large RT/Small CT

CT

OUTPUT

Small RT/ Large CT

4

CD

R

D

RT

T

T

=

ƒ

=ƒ

( )

OSCL

H

OSCK

Kln

1.631

ASTEC Semiconductor


49

Table 1. RT vs Maximum DutyRatio

RT (Ω) Dmax

470 22%

560 37%

683 50%

750 54%

820 58%

910 63%

1,000 66%

1,200 72%

1,500 77%

1,800 81%

2,200 85%

2,700 88%

3,300 90%

3,900 91%

4,700 93%

5,600 94%

6,800 95%

8,200 96%

10,000 97%

18,000 98%

that compensates for all of the tolerances withinthe device (such as the tolerances of VREG,propagation delays, the oscillator trip points,etc.) which have an effect on the frequency andmaximum duty ratio. For example, if the com-bined tolerances of a particular device are 0.5%above nominal, then ID is trimmed to 0.5% abovenominal. This method of trimming virtuallyeliminates the need to trim external oscillatorcomponents during power supply manufactur-

KV

LREG=

−≈ ( )V

VL

REG

0.736 3

KV

HREG=

−≈ ( )V

VH

H

0.4 432

where fosc is the oscillator frequency, D is themaximum duty ratio, VH is the oscillator’s uppertrip point, VL is the lower trip point, VR is theReference voltage, ID is the discharge current.

Table 1 lists some common values of RT and thecorresponding maximum duty ratio. To select thetiming components; first, use Table 1 or equation(2) to determine the value of RT that will yield thedesired maximum duty ratio. Then, use equation(1) to calculate the value of CT. For example, fora switching frequency of 250 kHz and a maxi-mum duty ratio of 50%, the value of RT, fromTable 1, is 683 Ω. Applying this value to equation(1) and solving for CT gives a value of 4700 pF. Inpractice, some fine tuning of the initial valuesmay be necessary during design. However, dueto the advanced design of the AS2842 oscillator,once the final values are determined, they willyield repeatable results, thus eliminating the needfor additional trimming of the timing componentsduring manufacturing.

1.3.2 Oscillator enhancements

The AS2842 oscillator is trimmed to provideguaranteed duty ratio clamping. This means thatthe discharge current (ID ) is trimmed to a value

RV

I

K K

K KT

REG

D

L H

L H

D D

D

D

D

D

D D

D

D

D

D

= ⋅ ( ) ( )( ) ( )

( )

= ⋅ ( ) − ( )−

− −

− −

1 1

1 1

1 1

1 1582

0 736 0 432

0 736 0 432

–

–

. .

( . ) ( . )

2



ing. Standard 2842 devices specify or trim onlyfor a specific value of discharge current. Thismakes precise and repeatable duty ratio clamp-ing virtually impossible due to other IC toler-ances. The AS2844/5 provides true 50% dutyratio clamping by virtue of excluding from its flip-flop scheme, the normal output blanking associ-ated with the discharge of CT. Standard AS2844/5 devices include the output blanking associatedwith the discharge of CT, resulting in somewhatless than a 50% duty ratio.

1.3.3 Synchronization

The advanced design of the AS2842 oscillatorsimplifies synchronizing the frequency of two ormore devices to each other or to an externalclock. The RT/CT doubles as a synchronizationinput which can easily be driven from any opencollector logic output. Figure 16 shows somesimple circuits for implementing synchroniza-tion.

1.4 Error amplifier (COMP)

The AS2842 error amplifier is a wide bandwidth,internally compensated operational amplifierwhich provides a high DC open loop gain (90 dB).The input to the amplifier is a PNP differentialpair. The non-inverting (+) input is internallyconnected to the 2.5 V reference, and the invert-ing (–) input is available at pin 2 (VFB). The outputof the error amplifier consists of an active pull-down and a 0.8 mA current source pull-up asshown in Figure 17. This type of output stageallows easy implementation of soft start, latchedshutdown and reduced current sense clamp func-tions. It also permits wire “OR-ing” of the erroramplifier outputs of several 2842s, or completebypass of the error amplifier when its output isforced to remain in its “pull-up” condition.

Figure 16. Synchronization

Figure 17. Er

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