May 2000
LP3961/LP3964
800mA Fast Ultra Low Dropout Linear Regulators
General Description
Features
n Ultra low dropout voltage
n Low ground pin current
The LP3961/LP3964 series of fast ultra low-dropout linear
regulators operate from a +2.5V to +7.0V input supply. Wide
range of preset output voltage options are available. These
ultra low dropout linear regulators respond very fast to step
changes in load which makes them suitable for low voltage
microprocessor applications. The LP3961/LP3964 are de-
veloped on a CMOS process which allows low quiescent
current operation independent of output load current. This
CMOS process also allows the LP3961/LP3964 to operate
under extremely low dropout conditions.
n Load regulation of 0.02%
n 15µA quiescent current in shutdown mode
n Guaranteed output current of 0.8A DC
n Available in SOT-223,TO-263 and TO-220 packages
n Output voltage accuracy 1.5%
n Error flag indicates output status (LP3961)
n Sense option improves better load regulation (LP3964)
n Extremely low output capacitor requirements
n Overtemperature/overcurrent protection
±
Dropout Voltage: Ultra low dropout voltage; typically 24mV
at 80mA load current and 240mV at 800mA load current.
n −40˚C to +125˚C junction temperature range
Ground Pin Current: Typically 4mA at 800mA load current.
Shutdown Mode: Typically 15µA quiescent current when
the shutdown pin is pulled low.
Applications
n Microprocessor power supplies
n GTL, GTL+, BTL, and SSTL bus terminators
n Power supplies for DSPs
n SCSI terminator
Error Flag: Error flag goes low when the output voltage
drops 10% below nominal value (for LP3961).
SENSE: Sense pin improves regulation at remote loads.
(For LP3964)
n Post regulators
Precision Output Voltage: Multiple output voltage options
n High efficiency linear regulators
n Battery chargers
are available ranging from 1.2V to 5.0V and adjustable, with
±
a guaranteed accuracy of 1.5% at room temperature, and
±
3.0% over all conditions ( varying line, load, and tempera-
n Other battery powered applications
ture).
Typical Application Circuits
DS101129-1
# Minimum output capacitance is 10 µF to ensure stability over full load current range. More capacitance provides superior dynamic performance and additional
stability margin.
*SD and ERROR pins must be pulled high through a 10kΩ pull-up resistor. Connect the ERROR pin to ground if this function is not used. See applications sec-
tion for more information.
© 2000 National Semiconductor Corporation
DS101129
www.national.com