NIKO-SEM
L431L
1
1.24V Low-Voltage Adjustable
Precision Shunt Regulator
GENERAL DESCRIPTION
The L431L is a three-terminal adjustable shunt
regulator utilizing an accurate 1.24V band gap
reference. The output voltage can be set to any
value between 1.24V (VREF) to 18V with two
external resistors as shown in the typical
application circuit. The device exhibit a wide
operating current range of 0.2 to 100 mA with a
typical dynamic impedance of 0.25Ω. Active
output circuitry provides a very sharp turn-on
characteristic, making the L431L excellent re-
placements for low-voltage zener diodes in
many applications, including on-board regulat-
ion and adjustable power supplies.
When used with an opto-coupler, the L431L is
ideal voltage reference in isolated feedback
circuits for 3.3V switching-mode power supplies.
The L431L shunt regulator is available in two
voltage tolerances (0.5% & 1.0%) and three
package options (TO-92, SOT-23-3 and SO-8).
FEATURES
Internal amplifier with 100 mA capability
Programmable output voltage to 18V
0.25Ω typical output impedance
Pin to pin compatible with TLV431A,
TS431, SC431L & AS432
Trimmed bandgap design 0.5% & 1.0%
with three package options
Low output noise
APPLICATIONS
Linear regulator controller
Precision voltage reference
Switching power supplies
Battery operating equipment
Instrumentation
PCs, Computer disk drives
SYMBOL & BLOCK DIAGRAM
Anode (A)
Cathod
Reference
-
+
Cathode (K)
Anode (A)
Reference (R)
1.24 Vref
FUNCTIONAL BLOCK DIAGRAM
SYMBOL
(R)
(K)
APR-25-2002
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