March 2002
LM431
Adjustable Precision Zener Shunt Regulator
General Description
Features
n Average temperature coefficient 50 ppm/˚C
The LM431 is a 3-terminal adjustable shunt regulator with
guaranteed temperature stability over the entire temperature
range of operation. It is now available in a chip sized pack-
age (4-Bump micro SMD) using National’s micro SMD pack-
age technology. The output voltage may be set at any level
greater than 2.5V (VREF) 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 excel-
lent replacement for many zener diode applications.
n Temperature compensated for operation over the full
temperature range
n Programmable output voltage
n Fast turn-on response
n Low output noise
n LM431 in micro SMD package
n See AN-1112 for micro SMD considerations
Connection Diagrams
TO-92: Plastic Package
SOT-23: 3-Lead Small Outline
DS010055-28
DS010055-1
Top View
Top View
4-Bump micro SMD
SO-8: 8-Pin Surface Mount
DS010055-54
DS010055-2
Top View
(bump side down)
Top view
*
Note: NC = Not internally connected. Must be electrically isolated from the
rest of the circuit for the microSMD package.
© 2002 National Semiconductor Corporation
DS010055
www.national.com
NSC [ National Semiconductor ]
