LMV431/LMV431A/LMV431B

Low-Voltage (1.24V) Adjustable Precision Shunt

Regulators

General Description

The LMV431, LMV431A and LMV431B are precision 1.24V

shunt regulators capable of adjustment to 30V. Negative

feedback from the cathode to the adjust pin controls the

cathode voltage, much like a non-inverting op amp configu-

ration (Refer to Symbol and Functional diagrams). A two

resistor voltage divider terminated at the adjust pin controls

the gain of a 1.24V band-gap reference. Shorting the cath-

ode to the adjust pin (voltage follower) provides a cathode

voltage of a 1.24V.

The LMV431, LMV431A and LMV431B have respective ini-

tial tolerances of 1.5%, 1% and 0.5%, and functionally lends

themselves to several applications that require zener diode

type performance at low voltages. Applications include a 3V

to 2.7V low drop-out regulator, an error amplifier in a 3V

off-line switching regulator and even as a voltage detector.

These parts are typically stable with capacitive loads greater

than 10nF and less than 50pF.

The LMV431, LMV431A and LMV431B provide performance

at a competitive price.

Features

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Low Voltage Operation/Wide Adjust Range (1.24V/30V)

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0.5% Initial Tolerance (LMV431B)

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Temperature Compensated for Industrial Temperature

Range (39 PPM/˚C for the LMV431AI)

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Low Operation Current (55µA)

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Low Output Impedance (0.25

Ω)

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Fast Turn-On Response

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Low Cost

Applications

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Shunt Regulator

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Series Regulator

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Current Source or Sink

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Voltage Monitor

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Error Amplifier

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3V Off-Line Switching Regulator

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Low Dropout N-Channel Series Regulator

Connection Diagrams

TO92: Plastic Package

10095801

Top View

SOT23-5

10095844

*Pin 1 is not internally connected.

*Pin 2 is internally connected to Anode pin. Pin 2 should be either floating

or connected to Anode pin.

Top View

SOT23-3

10095867

Top View

May 2005

© 2005 National Semiconductor Corporation

DS100958

www.national.com