Spec. No. : C504N3
Issued Date : 2003.03.21
Revised Date : 2005.10.07
Page No. : 1/9
CYStech Electronics Corp.
Adjustable shunt regulator
LM432XA3/N3
Description
Features
The LM432 is a three terminal adjustable shunt
regulator with thermal stability guaranteed over
temperature. The output voltage can be adjusted
to any value from 1.24V(VREF) to 20V with two
external resistors. The LM432 has a typical dynamic
output impedance of 0.05Ω. Active output circuitry
provides a very sharp turn on characteristic, making
◆Low voltage operation(down to 1.24V)
◆Wide operating current range 80μA to 100mA
◆Low dynamic output impedance 0.05Ω typ.
◆Trimmed bandgap design ±0.25%
◆Upgrade for LM431
◆Available in TO-92 and SOT-23 packages
the LM432 an excellent replacement for zener diodes. Applications
The LM432 shunt regulator is available with four
voltage tolerances(0.25%,0.5%,1% and 2%), and two
◆Linear Regulators
◆Adjustable Supplies
package options(TO-92 and SOT-23). This allows the ◆Switching Power Supplies
designer the opportunity to select the optimum combi- ◆Battery Operated Computers
nation of cost and performance for their application.
◆Instrumentation
◆Computer Disk Drives
Typical Application Circuit(Note 1,2)
Notes:
1) Set VOUT according to the following equation:
R
VIN
VOUT
VOUT=VREF(1+R1/R2)+IREFR1
2) Choose the value for R as follows:
˙The maximum limit for R should be such that the
cathode current, Iz, is greater than the minimum
operating current(80μA) at VIN(MIN).
˙The minimum limit for R should be as such that Iz
does not exceed 100mA under all load conditions,
and the instantaneous turn-on value for Iz does not
exceed 150mA. Both of the following conditions
must be met:
R1
VREF
PL432
LM432
R2
GND
Rmin≥VIN(max)/150mA(to limit instantaneous
turn-on Iz)
Rmin≥ VIN(max)-VOUT
(to limit Iz under
IOUT(min)+100mA normal operating
conditions)
LM432XA3/N3
CYStek Product Specification
CYSTEKEC [ CYSTECH ELECTONICS CORP. ]
