LM2601

Adapter Interface Circuit

General Description

The Adapter Interface Circuit (AIC) is used to sense the

presence of an external power source for a portable com-

puter. It notifies the computer if a source is present and

indicates if the source is appropriate for charging battery

packs inside the computer. The AIC also senses an adapter

current and its direction. AIC isolates the adapter and signals

the computer when peak current threshold is exceeded.

LM2601 drives P-channel FETs. No high current rated

Schottky diode is required to implement an adapter switcho-

ver circuit. This significantly decreases additional heat dissi-

pation during simultaneous fast battery charging while run-

ning a computer, particularly in Maximum Performance

mode of operation

Features

n

Detects an AC-DC adapter suitable for battery charging

or an airplane or car power line adapter that should not

be used for battery charging

n

Allows the implementation of intelligent switchover

circuits for portable systems

n

LM2601 shuts down automatically when adapter is

removed

n

Low leakage current from battery when not powered

n

Drives P-channel FETs, no Schottky diodes are required

n

No reverse inrush current from battery into the adapter

output capacitance

n

Allows for battery capacity gas-gauge calibration under

system software/firmware control

n

Adapter over current threshold programmable with

external resistors

n

Wide input range: 5V - 24V

n

Available in TSSOP-14 package

Applications

n

Portable Computers

n

Portable IAs (Internet Appliances, Information

Appliances)

n

Other Battery Powered Devices

Block Diagram

10130901

April 2001

© 2001 National Semiconductor Corporation

DS101309

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