LM431.PDF

December 1996

LM431

Adjustable Precision Zener Shunt Regulator

General Description

The LM431 is a 3-terminal adjustable shunt regulator with

guaranteed temperature stability over the entire tempera-

ture range of operation. The output voltage may be set at

any level greater than 2.5V (V REF ) up to 36V merely by

selecting two external resistors that act as a voltage divided

network. Due to the sharp turn-on characteristics this device

is an excellent replacement for many zener diode applica-

tions.

Features

Y Average temperature coefficient 50 ppm/ § C

Y Temperature compensated for operation over the full

temperature range

Y Programmable output voltage

Y Fast turn-on response

Y Low output noise

Connection Diagrams

TO-92: Plastic Package

SO-8: 8-Pin Surface Mount

SOT-23: 3-Lead Small Outline

TL/H/10055±2

TL/H/10055±28

TL/H/10055±1

Top View

Order Number LM431ACM,

LM431AIM,

LM431BCM, LM431BIM, LM431CCM

or LM431CIM

Top View

Order Number LM431ACM3,

LM431AIM3,

LM431BCM3, LM431BIM3,

LM431CCM3

or LM431CIM3

Top View

Order Number LM431ACZ,

LM431AIZ,

LM431BCZ, LM431BIZ, LM431CCZ

or LM431CIZ

Ordering Information*

Package

Typical Accuracy

Temperature Range

0.5%

TO-92

LM431CCZ

LM431BCZ

LM431ACZ

0 § Cto a 70 § C

LM431CIZ

LM431BIZ

LM431AIZ

b 40 § Cto a 85 § C

SO-8

LM431CCM

LM431BCM

LM431ACM

0 § Cto a 70 § C

LM431CIM

LM431BIM

LM431AIM

b 40 § Cto a 85 § C

SOT-23

LM431CCM3

LM431BCM3

LM431ACM3

0 § Cto a 70 § C

LM431CIM3

LM431BIM3

LM431AIM3

b 40 § Cto a 85 § C

*See Table 1 for package marking for SOT-23.

C 1996 National Semiconductor Corporation

TL/H/10055

RRD-B30M17/Printed in U. S. A.

http://www.national.com

Absolute Maximum Ratings

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales

Office/Distributors for availability and specifications.

Storage Temperature Range

Cathode Voltage 37V

Continuous Cathode Current b 10 mA to a 150 mA

Reference Voltage

b 0.5V

b 65 § Cto a 150 § C

Reference Input Current

10 mA

Operating Temperature Range

Industrial (LM431xI)

b 40 § Cto a 85 § C

Operating Conditions

Min

Max

Cathode Voltage

V REF

37V

Commercial (LM431xC)

0 § Cto a 70 § C

Cathode Current

1.0 mA

100 mA

Lead Temperature

TO-92 Package/SO-8 Package/SOT-23 Package

(Soldering, 10 sec.)

265 § C

Note 1: T J Max e 150 § C.

Note 2: Ratings appy to ambient temperature at 25 § C. Above this tempera-

ture, derate the TO-92 at 6.2 mW/ § C, the SO-8 at 6.5 mW/ § C, and the

SOT-23 at 2.2 mW/ § C.

Internal Power Dissipation (Notes 1, 2)

TO-92 Package

0.78W

SO-8 Package

0.81W

SOT-23 Package

0.28W

LM431

Electrical Characteristics T A e 25 § C unless otherwise specified

Symbol

Parameter

Conditions

Min Typ Max Units

V REF Reference Voltage

V Z e V REF ,I I e 10 mA

2.440 2.495 2.550 V

LM431A (Figure1)

V Z e V REF ,I I e 10 mA

2.470 2.495 2.520 V

LM431B (Figure1)

V Z e V REF ,I I e 10 mA

2.485 2.500 2.510 V

LM431C(Figure1)

V DEV Deviation of Reference Input

Voltage Over Temperature (Note 3) T A e Full Range (Figure1)

V Z e V REF ,I I e 10 mA,

8.0

17 mV

D V REF

D V Z

Ratio of the Change in Reference

I Z e 10 mA V Z from V REF to 10V

b 1.4 b 2.7

mV/V

Voltage to the Change in Cathode

(Figure2)

V Z from 10V to 36V

b 1.0 b 2.0

Voltage

I REF

Reference Input Current

R 1 e 10 k X ,R 2 e % ,

2.0

4.0 m A

I I e 10 mA (Figure2)

* I REF Deviation of Reference Input Current R 1 e 10 k X ,R 2 e % ,

over Temperature

I I e 10 mA,

0.4

1.2 m A

T A e Full Range (Figure2)

Regulation

I Z(OFF) Off-State Current

V Z e V REF (Figure1)

0.4

1.0 mA

V Z e 36V, V REF e 0V (Figure3)

0.3

1.0 m A

r Z

Dynamic Output Impedance (Note 4) V Z e V REF , LM431A,

Frequency e 0Hz(Figure1)

V Z e V REF , LM431B, LM431C

0.75 X

0.50 X

Frequency e 0Hz(Figure1)

http://www.national.com

I Z(MIN) Minimum Cathode Current for

LM431

Electrical Characteristics T A e 25 § C unless otherwise specified (Continued)

Note 3: Deviation of reference input voltage, V DEV , is defined as the maximum variation of the reference input voltage over the full temperature range.

TL/H/10055±7

The average temperature coefficient of the reference input voltage, * V REF , is defined as:

V Max b V Min

V REF (at 25 § C)

(

10 6

V DEV

V REF (at 25 § C)

(

10 6

ppm

§ C e

* V REF

T 2 b T 1

Where:

T 2 b T 1 e full temperature change.

* V REF can be positive or negative depending on whether the slope is positive or negative.

Example: V DEV e 8.0 mV, V REF e 2495 mV, T 2 b T 1 e 70 § C, slope is positive.

* V REF e

10 6

70 § C ea 46 ppm/ § C

(

Note 4: The dynamic output impedance, r Z , is defined as:

D V Z

D I Z

When the device is programmed with two external resistors, R1 and R2, (see Figure2), the dynamic output impedance of the overall circuit, r Z , is defined as:

r Z e