background image

TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

1

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

D

Equivalent Full-Range Temperature

Coefficient . . . 30 ppm/

°

C

D

0.2-

 Typical Output Impedance

D

Sink-Current Capability . . . 1  mA  to  100 mA

D

Low Output Noise

D

Adjustable Output Voltage . . . V

ref

 to 36 V

D

Available in a Wide Range of High-Density

Packages

description

The TL431 and TL431A are three-terminal

adjustable shunt regulators with specified thermal

stability over applicable automotive, commercial,

and military temperature ranges. The output

voltage can be set to any value between V

ref

(approximately 2.5 V) and 36 V with two external

resistors (see Figure 17). These devices have a

typical output impedance of 0.2 

. Active output

circuitry provides a very sharp turn-on

characteristic, making these devices excellent

replacements for Zener diodes in many

applications, such as onboard regulation,

adjustable power supplies, and switching power

supplies.

The TL431C and TL431AC are characterized for

operation from 0

°

C to 70

°

C, and the TL431I and

TL431AI are characterized for operation from

–40

°

C to 85

°

C.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

1

2

3

4

8

7

6

5

CATHODE

ANODE

ANODE

NC

REF

ANODE

ANODE

NC

D PACKAGE

(TOP VIEW)

1

2

3

4

8

7

6

5

CATHODE

NC

NC

NC

REF

NC

ANODE

NC

P OR PW PACKAGE

(TOP VIEW)

PK PACKAGE

(TOP VIEW)

LP PACKAGE

(TOP VIEW)

REF ANODE CATHODE

CATHODE

ANODE

REF

CATHODE

ANODE

REF

ANODE

KTP PACKAGE

(TOP VIEW)

NC – No internal connection

 

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Copyright 

©

 1999, Texas Instruments Incorporated

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

2

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

AVAILABLE OPTIONS

PACKAGED DEVICES

TA

SMALL

OUTLINE

(D)

PLASTIC

FLANGE

MOUNT

(KTP)

TO-226AA

(LP)

PLASTIC

DIP

(P)

SOT-89

(PK)

SHRINK

SMALL

OUTLINE

(PW)

CHIP

FORM

(Y)

0

°

C to 70

°

C

TL431CD

TL431ACD

TL431CKTPR

TL431CLP

TL431ACLP

TL431CP

TL431ACP

TL431CPK

TL431CPW

TL431Y

–40

°

C to 85

°

C

TL431ID

TL431AID

TL431ILP

TL431AILP

TL431IP

TL431AIP

TL431IPK

TL431Y

The D and LP packages are available taped and reeled. The KTP and PK packages are only available taped and reeled. Add

the suffix R to device type (e.g., TL431CDR). Chip forms are tested at TA = 25

°

C.

symbol

REF

CATHODE

ANODE

functional block diagram

CATHODE

REF

ANODE

+

_

Vref

equivalent schematic

ANODE

REF

CATHODE

2.4 k

7.2 k

3.28 k

20 pF

4 k

1 k

800 

800 

800 

20 pF

150 

10 k

† All component values are nominal.

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

3

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

absolute maximum ratings over operating free-air temperature range (unless otherwise noted)

Cathode voltage, V

KA

 (see Note 1) 

37 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Continuous cathode current range, I

KA

 

–100 mA to 150 mA

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Reference input current range 

–50 

µ

A to 10 mA

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Package thermal impedance, 

θ

JA

 (see Notes 2 and 3): D package

97

°

C/W

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 

LP package

156

°

C/W

. . . . . . . . . . . . . . . . . . . . . . . . . . 

KTP package

28

°

C/W

. . . . . . . . . . . . . . . . . . . . . . . . . 

P package

127

°

C/W

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 

PK package

52

°

C/W

. . . . . . . . . . . . . . . . . . . . . . . . . . . 

PW package

149

°

C/W

. . . . . . . . . . . . . . . . . . . . . . . . . . 

Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds: D, P, or PW package 

260

°

C

. . . . . . . . . . . . 

Lead temperature 1,6 mm (1/16 inch) from case for 60 seconds: LP or PK package 

300

°

C

. . . . . . . . . . . . . . 

Storage temperature range, T

stg

 –65

°

C to 150

°

C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

† 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 under “recommended operating conditions” is not

implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

NOTES:

1. Voltage values are with respect to the anode terminal unless otherwise noted.

2. Maximum power dissipation is a function of TJ(max), 

θ

JA, and TA. The maximum allowable power dissipation at any allowable

ambient temperature is PD = (TJ(max) – TA)/

θ

JA. Operating at the absolute maximum TJ of 150

°

C can impact reliability.

3. The package thermal impedance is calculated in accordance with JESD 51, except for through-hole packages, which use a trace

length of zero.

recommended operating conditions

MIN

MAX

UNIT

Cathode voltage, VKA

Vref

36

V

Cathode current, IKA

1

100

mA

Operating free air temperature range TA

TL431C, TL431AC

0

70

°

C

Operating free-air temperature range, TA

TL431I, TL431AI

–40

85

°

C

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

4

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

electrical characteristics over recommended operating conditions, T

A

 = 25

°

C (unless otherwise

noted)

PARAMETER

TEST

TEST CONDITIONS

TL431C

UNIT

PARAMETER

CIRCUIT

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Vref

Reference voltage

2

VKA = Vref,

IKA = 10 mA

2440

2495

2550

mV

VI(dev)

Deviation of reference voltage

over full temperature range

(see Figure 1)

2

VKA = Vref, IKA = 10 mA,

TA = full range†

4

25

mV

D

V

ref

Ratio of change in reference voltage

3

IKA = 10 mA

VKA = 10 V – Vref

–1.4

–2.7

mV

ref

D

V

KA

g

g

to the change in cathode voltage

3

IKA = 10 mA

VKA = 36 V – 10 V

–1

–2

mV

V

Iref

Reference current

3

IKA = 10 mA, R1 = 10 k

, R2 = 

2

4

µ

A

II(dev)

Deviation of reference current

over full temperature range

(see Figure 1)

3

IKA = 10 mA, R1 = 10 k

, R2 = 

,

TA = full range†

0.4

1.2

µ

A

Imin

Minimum cathode current

for regulation

2

VKA = Vref

0.4

1

mA

Ioff

Off-state cathode current

4

VKA = 36 V,

Vref = 0

0.1

1

µ

A

|zKA|

Dynamic impedance (see Figure 1)

1

IKA = 1 mA to 100 mA, VKA = Vref,

 1 kHz

0.2

0.5

† Full range is 0

°

C to 70

°

C for the TL431C.

The deviation parameters V

ref(dev)

 and I

ref(dev)

 are defined as the differences between the maximum and minimum

values obtained over the recommended temperature range. The average full-range temperature coefficient of the

reference voltage, 

α

Vref

, is defined as:

where:

T

A

 is the recommended operating free-air temperature range of the device.

α

Vref

 can be positive or negative, depending on whether minimum V

ref

 or maximum V

ref

, respectively, occurs at the

lower temperature.

Example: maximum V

ref

 = 2496 mV at 30

°

C, minimum V

ref

 = 2492 mV at 0

°

C, V

ref

 = 2495 mV at 25

°

C,

T

= 70

°

C for TL431C

Because minimum V

ref

 occurs at the lower temperature, the coefficient is positive.

Calculating Dynamic Impedance

The dynamic impedance is defined as:

When the device is operating with two external resistors (see Figure 3), the total dynamic impedance of the circuit

is given by:

Maximum Vref

Minimum Vref

TA

VI(dev)

Ť

a

Vref

Ť

ǒ

ppm

°

C

Ǔ

+

ǒ

V

I(dev)

V

ref

at 25

°

C

Ǔ

 

106

D

T

A

Ť

a

Vref

Ť

+

ǒ

4 mV

2495 mV

Ǔ

 

106

70

°

C

[

23 ppm

ń

°

C

Ť

z

KA

Ť

+

D

V

KA

D

I

KA

|z

Ȁ

|

+ D

V

D

I

[

Ť

z

KA

Ť

ǒ

1

)

R1

R2

Ǔ

Figure 1. Calculating Deviation Parameters and Dynamic Impedance

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

5

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

electrical characteristics over recommended operating conditions, T

A

 = 25

°

C (unless otherwise

noted)

PARAMETER

TEST

TEST CONDITIONS

TL431I

UNIT

PARAMETER

CIRCUIT

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Vref

Reference voltage

2

VKA = Vref,

IKA = 10 mA

2440

2495

2550

mV

VI(dev)

Deviation of reference voltage

over full temperature range

(see Figure 1)

2

VKA = Vref, IKA = 10 mA,

TA = full range†

5

50

mV

D

V

ref

Ratio of change in reference voltage

3

IKA = 10 mA

VKA = 10 V – Vref

–1.4

–2.7

mV

ref

D

V

KA

g

g

to the change in cathode voltage

3

IKA = 10 mA

VKA = 36 V – 10 V

–1

–2

mV

V

Iref

Reference current

3

IKA = 10 mA, R1 = 10 k

, R2 = 

2

4

µ

A

II(dev)

Deviation of reference current

over full temperature range

(see Figure 1)

3

IKA = 10 mA, R1 = 10 k

, R2 = 

,

TA = full range†

0.8

2.5

µ

A

Imin

Minimum cathode current for

regulation

2

VKA = Vref

0.4

1

mA

Ioff

Off-state cathode current

4

VKA = 36 V,

Vref = 0

0.1

1

µ

A

|zKA|

Dynamic impedance (see Figure 1)

2

IKA = 1 mA to 100 mA, VKA = Vref,

 1 kHz

0.2

0.5

† Full range is –40

°

C to 85

°

C for the TL431I.

electrical characteristics over recommended operating conditions, T

A

 = 25

°

C (unless otherwise

noted)

PARAMETER

TEST

TEST CONDITIONS

TL431AC

UNIT

PARAMETER

CIRCUIT

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Vref

Reference voltage

2

VKA = Vref,

IKA = 10 mA

2470

2495

2520

mV

VI(dev)

Deviation of reference voltage

over full temperature range

(see Figure 1)

2

VKA = Vref, IKA = 10 mA,

TA = full range†

4

25

mV

D

V

ref

Ratio of change in reference voltage

3

IKA = 10 mA

VKA = 10 V – Vref

–1.4

–2.7

mV

ref

D

V

KA

g

g

to the change in cathode voltage

3

IKA = 10 mA

VKA = 36 V – 10 V

–1

–2

mV

V

Iref

Reference current

3

IKA = 10 mA, R1 = 10 k

, R2 = 

2

4

µ

A

II(dev)

Deviation of reference current

over full temperature range

(see Figure 1)

3

IKA = 10 mA, R1 = 10 k

, R2 = 

,

TA = full range‡

0.8

1.2

µ

A

Imin

Minimum cathode current

for regulation

2

VKA = Vref

0.4

0.6

mA

Ioff

Off-state cathode current

4

VKA = 36 V,

Vref = 0

0.1

0.5

µ

A

|zKA|

Dynamic impedance (see Figure 1)

1

IKA = 1 mA to 100 mA, VKA = Vref,

 1 kHz

0.2

0.5

‡ Full range is 0

°

C to 70

°

C for the TL431AC.

background image

TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

6

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

electrical characteristics over recommended operating conditions, T

A

 = 25

°

C (unless otherwise

noted)

PARAMETER

TEST

TEST CONDITIONS

TL431AI

UNIT

PARAMETER

CIRCUIT

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Vref

Reference voltage

2

VKA = Vref,

IKA = 10 mA

2470

2495

2520

mV

VI(dev)

Deviation of reference voltage

over full temperature range

(see Figure 1)

2

VKA = Vref, IKA = 10 mA,

TA = full range†

5

50

mV

D

V

ref

Ratio of change in reference voltage

3

IKA = 10 mA

VKA = 10 V – Vref

–1.4

–2.7

mV

ref

D

V

KA

g

g

to the change in cathode voltage

3

IKA = 10 mA

VKA = 36 V – 10 V

–1

–2

mV

V

Iref

Reference current

3

IKA = 10 mA, R1 = 10 k

, R2 = 

2

4

µ

A

II(dev)

Deviation of reference current

over full temperature range

(see Figure 1)

3

IKA = 10 mA, R1 = 10 k

, R2 = 

,

TA = full range†

0.8

2.5

µ

A

Imin

Minimum cathode current

for regulation

2

VKA = Vref

0.4

0.7

mA

Ioff

Off-state cathode current

4

VKA = 36 V,

Vref = 0

0.1

0.5

µ

A

|zKA|

Dynamic impedance (see Figure 1)

2

IKA = 1 mA to 100 mA, VKA = Vref,

 1 kHz

0.2

0.5

† Full range is –40

°

C to 85

°

C for the TL431AI.

electrical characteristics over recommended operating conditions, T

A

 = 25

°

C (unless otherwise

noted)

PARAMETER

TEST

TEST CONDITIONS

TL431Y

UNIT

PARAMETER

CIRCUIT

TEST CONDITIONS

MIN

TYP

MAX

UNIT

Vref

Reference voltage

2

VKA = Vref,

IKA = 10 mA

2495

mV

D

V

ref

Ratio of change in reference voltage

3

IKA = 10 mA

VKA = 10 V – Vref

–1.4

mV

ref

D

V

KA

g

g

to the change in cathode voltage

3

IKA = 10 mA

VKA = 36 V – 10 V

–1

mV

V

Iref

Reference input current

3

IKA = 10 mA, R1 = 10 k

, R2 = 

2

µ

A

Imin

Minimum cathode current

for regulation

2

VKA = Vref

0.4

mA

Ioff

Off-state cathode current

4

VKA = 36 V,

Vref = 0

0.1

µ

A

|zKA|

Dynamic impedance‡

2

IKA = 1 mA to 100 mA, VKA = Vref,

 1 kHz

0.2

‡ Calculating dynamic impedance:

The dynamic impedance is defined as: 

Ť

z

KA

Ť

+

D

V

KA

D

I

KA

When the device is operating with two external resistors (see Figure 3), the total dynamic impedance of the circuit is given by:

| z

Ȁ

|

+

V

I

[

| z

KA

|

ǒ

1

)

R1

R2

Ǔ

background image

TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

7

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

PARAMETER MEASUREMENT INFORMATION

Vref

Input

VKA

IKA

Figure 2. Test Circuit for V

KA

 = V

ref

V

KA

+

V

ref

ǒ

1

)

R1

R2

Ǔ

)

I

ref

 

R1

Iref

IKA

VKA

Input

Vref

R1

R2

Figure 3. Test Circuit for V

KA

 > V

ref

Ioff

VKA

Input

Figure 4. Test Circuit for I

off

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

8

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

TYPICAL CHARACTERISTICS

Table 1. Graphs

FIGURE

Reference input voltage vs Free-air temperature

5

Reference input current vs Free-air temperature

6

Cathode current vs Cathode voltage

7, 8

Off-state cathode current vs Free-air temperature

9

Ratio of delta reference voltage to change in cathode voltage vs Free-air temperature

10

Equivalent input noise voltage vs Frequency

11

Equivalent input noise voltage over a 10-second period

12

Small-signal voltage amplification vs Frequency

13

Reference impedance vs Frequency

14

Pulse response

15

Stability boundary conditions

16

Table 2. Application Circuits

FIGURE

Shunt regulator

17

Single-supply comparator with temperature-compensated threshold

18

Precision high-current series regulator

19

Output control of a three-terminal fixed regulator

20

High-current shunt regulator

21

Crowbar circuit

22

Precision 5-V 1.5-A regulator

23

Efficient 5-V precision regulator

24

PWM converter with reference

25

Voltage monitor

26

Delay timer

27

Precision current limiter

28

Precision constant-current sink

29

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

9

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

TYPICAL CHARACTERISTICS

‡ Data is for devices having the indicated value of Vref at IKA = 10 mA,

TA = 25

°

C.

Figure 5

2500

2480

2420

2400

–75

–50

–25

0

25

50

75

2540

2580

REFERENCE VOLTAGE

vs

FREE-AIR TEMPERATURE

2600

100

125

2460

2560

2520

2440

TA – Free-Air Temperature – 

°

C

Vref = 2495 mV‡

Vref = 2440 mV‡

VKA = Vref

IKA = 10 mA

Vref = 2550 mV‡

– Reference V

oltage – mV

V

ref

Figure 6

3

2

1

0

–75

–25

0

50

4

REFERENCE CURRENT

vs

FREE-AIR TEMPERATURE

5

100

125

–50

25

75

TA – Free-Air Temperature – 

°

C

R1 = 10 k

R2 = 

IKA = 10 mA

– Reference Current –

ref

I

A

µ

Figure 7

25

0

–50

–75

–100

125

–25

–2

–1

0

1

75

50

100

CATHODE CURRENT 

vs 

CATHODE VOLTAGE

150

2

3

VKA – Cathode Voltage – V

VKA = Vref

TA = 25

°

C

– Cathode Current – mA

I

KA

Figure 8

400

200

0

–200

–1

0

1

600

CATHODE CURRENT

vs

CATHODE VOLTAGE

800

2

3

VKA = Vref

TA = 25

°

C

VKA – Cathode Voltage – V

Imin

– Cathode Current – 

I

KA

A

µ

† Data at high and low temperatures are applicable only within the recommended operating free-air temperature ranges of the various devices.

background image

TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

10

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

TYPICAL CHARACTERISTICS

Figure 9

1.5

1

0.5

0

–75

–25

0

50

– Off-State Cathode Current – 

2

OFF-STATE CATHODE CURRENT

vs

FREE-AIR TEMPERATURE

2.5

100

125

–50

25

75

I

off

A

µ

TA – Free-Air Temperature – 

°

C

VKA = 36 V

Vref = 0

Figure 10

–1.15

–1.25

–1.35

–1.45

–1.05

– 0.95

RATIO OF DELTA REFERENCE VOLTAGE TO

DELTA CATHODE VOLTAGE

vs

FREE-AIR TEMPERATURE

– 0.85

TA – Free-Air Temperature – 

°

C

–75

–25

0

50

100

125

–50

25

75

VKA = 3 V to 36 V

– mV/V

V

ref

V

KA

/

180

140

120

100

10

100

1 k

220

240

f – Frequency – Hz

EQUIVALENT INPUT NOISE VOLTAGE

vs

FREQUENCY

260

10 k

100 k

200

160

– Equivalent Input Noise V

oltage –

nV/

Hz

V

n

IO = 10 mA

TA = 25

°

C

Figure 11

† Data at high and low temperatures are applicable only within the recommended operating free-air temperature ranges of the various devices.

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

11

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

TYPICAL CHARACTERISTICS

19.1 V

VCC

TLE2027

TLE2027

AV = 10 V/mV

VEE

0.1 

µ

F

160 k

820 

(DUT)

TL431

16 

910 

2000 

µ

F

1 k

VEE

VCC

µ

F

16 k

16 k

µ

F

33 k

33 k

AV = 2 V/V

22 

µ

F

500 

µ

F

To Oscilloscope

–1

–2

–4

–5

–6

3

–3

0

1

2

3

4

5

6

1

0

2

EQUIVALENT INPUT NOISE VOLTAGE

OVER A 10-SECOND PERIOD

4

7

8

9

10

5

6

t – Time – s

f = 0.1 to 10 Hz

IKA = 10 mA

TA = 25

°

C

    – Equivalent Input Noise voltage –

µ

V

V

n

+

+

Figure 12. Test Circuit for Equivalent Input Noise Voltage

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

12

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

TYPICAL CHARACTERISTICS

SMALL-SIGNAL VOLTAGE AMPLIFICATION

vs

FREQUENCY

µ

F

GND

Output

232 

8.25 k

IKA

15 k

40

20

10

0

60

30

1 k

10 k

100 k

1 M

10 M

50

f – Frequency – Hz

TEST CIRCUIT FOR VOLTAGE AMPLIFICATION

IKA = 10 mA

TA = 25

°

C

– Small-Signal V

oltage 

Amplification – dB

A

V

+

Figure 13

1 k

50 

GND

Output

IKA

0.1

1 k

10 k

100 k

1 M

10 M

1

f – Frequency – Hz

REFERENCE IMPEDANCE

vs

FREQUENCY

10

100

IKA = 10 mA

TA = 25

°

C

TEST CIRCUIT FOR REFERENCE IMPEDANCE

– Reference Impedance –

KA

|z

|

+

Figure 14

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

13

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

TYPICAL CHARACTERISTICS

3

2

1

0

–1

0

1

2

3

4

Input and Output V

oltage – V

4

5

PULSE RESPONSE

6

5

6

7

Input

Output

TA = 25

°

C

220

 Ω

50 

GND

Output

Pulse

Generator

f = 100 kHz

TEST CIRCUIT FOR PULSE RESPONSE

t – Time – 

µ

s

Figure 15

50

40

10

0

0.001

0.01

0.1

1

70

90

STABILITY BOUNDARY CONDITIONS

100

10

30

80

60

20

TA = 25

°

C

B

Stable

Stable

A VKA = Vref

B VKA = 5 V

C VKA = 10 V

D VKA = 15 Vf

CL – Load Capacitance – 

µ

F

A

C

D

150 

IKA

R1 = 10 k

R2

CL

VBATT

IKA

CL

VBATT

150 

TEST CIRCUIT FOR CURVE A

TEST CIRCUIT FOR CURVES B, C, AND D

– Cathode Current – mA

I

KA

† The areas under the curves represent conditions that may cause the

device to oscillate. For curves B, C, and D, R2 and V+ were adjusted

to establish the initial VKA and IKA conditions with CL = 0. VBATT and

CL were then adjusted to determine the ranges of stability.

+

+

Figure 16

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

14

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

APPLICATION INFORMATION

R1

0.1%

R2

0.1%

R

(see Note A)

Vref

VO

TL431

VI(BATT)

RETURN

NOTE A: R should provide cathode current 

1 mA to the TL431 at minimum VI(BATT).

V

O

+

ǒ

1

)

R1

R2

Ǔ

V

ref

Figure 17. Shunt Regulator

VO

TL431

VI(BATT)

VIT 

2.5 V

GND

Input

Von 

 2 V

Voff 

 VI(BATT)

Figure 18. Single-Supply Comparator With Temperature-Compensated Threshold

R

(see Note A)

VO

TL431

VI(BATT)

2N222

2N222

4.7 k

R1

0.1%

R2

0.1%

0.01 

µ

F

30 

V

O

+

ǒ

1

)

R1

R2

Ǔ

V

ref

NOTE A: R should provide cathode current 

1 mA to the TL431 at minimum VI(BATT).

Figure 19. Precision High-Current Series Regulator

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

15

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

APPLICATION INFORMATION

VO

TL431

VI(BATT)

uA7805

IN

OUT

Common

R1

R2

V

O

+

ǒ

1

)

R1

R2

Ǔ

V

ref

Minimum V

O

+

V

ref

)

5 V

Figure 20. Output Control of a Three-Terminal Fixed Regulator

VO

TL431

VI(BATT)

R1

R2

V

O

+

ǒ

1

)

R1

R2

Ǔ

V

ref

Figure 21. High-Current Shunt Regulator

VO

TL431

VI(BATT)

R1

R2

NOTE A: Refer to the stability boundary conditions in Figure 16 to determine allowable values for C.

C

(see Note A)

Figure 22. Crowbar Circuit

background image

TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

16

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

APPLICATION INFORMATION

VO 

 5 V, 1.5 A

TL431

VI(BATT)

LM317

IN

OUT

Adjust

243 

0.1%

243 

0.1%

8.2 k

Figure 23. Precision 5-V 1.5-A Regulator

VO 

 5 V

TL431

VI(BATT)

27.4 k

0.1%

Rb

(see Note A)

27.4 k

0.1%

NOTE A: Rb should provide cathode current 

1-mA to the TL431.

Figure 24. Efficient 5-V Precision Regulator

TL431

12 V

VCC

5 V

6.8 k

10 k

10 k

0.1%

10 k

0.1%

X

Not

Used

Feedback

TL598

+

Figure 25. PWM Converter With Reference

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TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

17

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

APPLICATION INFORMATION

TL431

VI(BATT)

R3

(see Note A)

R1A

R4

(see Note A)

R2B

R2A

NOTE A: R3 and R4 are selected to provide the desired LED intensity and cathode current 

1 mA to the TL431 at the available VI(BATT).

R1B

Low Limit

+

ǒ

1

)

R1B

R2B

Ǔ

V

ref

High Limit

+

ǒ

1

)

R1A

R2A

Ǔ

V

ref

LED on When Low Limit < VI(BATT) < High Limit

Figure 26. Voltage Monitor

TL431

650

 Ω

2 k

C

On

Off

R

12 V

Delay

+

R

 

C

 

I

n

ǒ

12 V

12 V

*

V

ref

Ǔ

Figure 27. Delay Timer

TL431

IO

RCL

0.1%

R1

VI(BATT)

I

out

+

V

ref

R

CL

)

I

KA

R1

+

V

I(BATT)

I

O

h

FE

)

I

KA

Figure 28. Precision Current Limiter

background image

TL431, TL431A

ADJUSTABLE PRECISION SHUNT REGULATORS

 

 

SLVS005J – JULY 1978 – REVISED JULY 1999

18

POST OFFICE BOX 655303 

 DALLAS, TEXAS 75265

APPLICATION INFORMATION

TL431

RS

0.1%

IO

VI(BATT)

I

O

+

V

ref

R

S

Figure 29. Precision Constant-Current Sink

background image

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Copyright 

©

 1999, Texas Instruments Incorporated