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www.fairchildsemi.com
Features
Low voltage operation to 1.24V
1% reference voltage tolerance
Output voltage adjustable from V
ref
to 12V
Low 80
m
A operational cathode current
0.25
W
typical output impedance
TO-92 and SOT23-5 packages
Applications
Voltage reference for discrete power circuits
Description
The RC431A is a low-voltage 3-terminal adjustable preci-
sion voltage reference regulator. It has an excellent thermal
stability over the standard commercial temperature range.
The output voltage can be set to any value between Vref
(1.24V) and 12V using two external resistors. The RC431A
operates from a lower voltage (1.24V) than the traditional
shunt regulator references which operate from 2.5V. When
used with an optocoupler, the RC431A will be an ideal volt-
age reference in an isolated feedback circuit for use in
switched-mode power supplies and modular DC-DC con-
verters. The RC431A has a low output impedance of active
output circuitry offering a very sharp turn-on characteristic.
The RC431A will be an excellent replacement for low-
voltage zener diodes in many applications such as on-board
regulation and adjustable power supplies.
Symbol
Block Diagram
RC431A
Low-Voltage Adjustable Prec ision S hunt Regulator
REF
65-431A-01
Anode
Cathode
V
ref
= 1.24V
REF
+
_
CATHODE
ANODE
65-431A-02
Rev. 1.0.3