August 2003
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
n Low Voltage Operation/Wide Adjust Range (1.24V/30V)
n 0.5% Initial Tolerance (LMV431B)
n Temperature Compensated for Industrial Temperature
Range (39 PPM/˚C for the LMV431AI)
n Low Operation Current (55µA)
n Low Output Impedance (0.25Ω)
n Fast Turn-On Response
n Low Cost
Applications
n Shunt Regulator
n Series Regulator
n Current Source or Sink
n Voltage Monitor
n Error Amplifier
n 3V Off-Line Switching Regulator
n Low Dropout N-Channel Series Regulator
Connection Diagrams
TO92: Plastic Package
SOT23-3
Top View
SOT23-5
10095801
*Pin 1 is not internally connected.
10095844
*Pin 2 is internally connected to Anode pin. Pin 2 should be either floating
or connected to Anode pin.
Top View
Top View
10095867
© 2003 National Semiconductor Corporation DS100958
www.national.com
