LM3881 Datasheet, PDF (1/14 Pages) National Semiconductor (TI) – Power Sequencer

February 6, 2008
LM3881
Power Sequencer
General Description
The LM3881 Power Sequencer offers the easiest method to
control power up and power down of multiple power supplies
(switching or linear regulators). By staggering the startup se-
quence, it is possible to avoid latch conditions or large in-rush
currents that can affect the reliability of the system.
Available in MSOP-8 package, the Power Sequencer con-
tains a precision enable pin and three open drain output flags.
Upon enabling the LM3881, the three output flags will se-
quentially release, after individual time delays, permitting the
connected power supplies to startup. The output flags will fol-
low a reverse sequence during power down to avoid latch
conditions. Time delays are defined using an external capac-
itor and the output flag states can be inverted by the user.
Features
■ ^{Easiest method to sequence rails}
■ ^{Power up and power down control}
■ ^{Input voltage range of 2.7V to 5.5V}
■ ^{Small footprint MSOP-8 package}
■ ^{Low quiescent current of 80 µA}
■ ^{Output invert feature}
■ ^{Timing controlled by small value external capacitor}
Applications
■ ^{Multiple Supply Sequencing}
■ ^{Microprocessor / Microcontroller Sequencing}
■ ^{FPGA Sequencing}
Typical Application Circuit
30048401
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