Interface Circuit. LM2601 Datasheet
Adapter Interface Circuit
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
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
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
n Allows for battery capacity gas-gauge calibration under
system software/firmware control
n Adapter over current threshold programmable with
n Wide input range: 5V - 24V
n Available in TSSOP-14 package
n Portable Computers
n Portable IAs (Internet Appliances, Information
n Other Battery Powered Devices
© 2001 National Semiconductor Corporation DS101309
* Partial Rails are available, there is no minimum order quantity. Tape and Reel is supplied as full reels only.
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Tape and Reel (2500
A capacitor between this pin and ground sets the delay of the MPS risetime. See MPS
DELAY description in Typical Application section.
Bi-directional logic pin. If driven high by an external source, indicates that a battery is
powering the power bus. If driven high by the AIC, indicates the adapter is powering the
bus. AIC cannot drive MPS low. If there is no valid adapter voltage present, the pin is not
an output but a high impedance logic input. The input is pulled-down via an internal 40k
Logic input pin. Active high. Grants permission to the adapter to drive both the power bus
and the MPS signal.
Logic output pin. High when 12 volts < VADAPTER < 17 volts. The output typically has 40k
pull-down resistor. The source current is not internally limited and the part can be
damaged if the output is shorted to ground when driven HIGH.
Logic output pin. High when VADAPTER > 17 volts. The output typically has 40k pull-down
resistor. The source current is not internally limited and the part can be damaged if the
output is shorted to ground when driven HIGH.
IC ground pin.
Drives the gate of the disconnect P-ch FET.
Drives the gate of the backfeed P-ch FET.
Connection for current sense resistor to control BACKFEED.
Connection for current sense resistor to control DISCONNECT.
Power input pin. Output of AC adapter, auto adapter or airline adapter.