LM2601MTCEVAL National Semiconductor Corporation, LM2601MTCEVAL Datasheet - Page 5

• Manufacturer Part Number: LM2601MTCEVAL
• Description: LM2601 - Adapter Interface Circuit Not Recommended For Designs , Package: Tssop, Pin Nb=14
• Manufacturer: National Semiconductor Corporation

Application Information
The adapter interface circuit (AIC) IC provides the control
functions necessary for use in mating a constant voltage
output AC-DC adapter or airline adapter to a notebook com-
puter system or a portable device. It allows optimal battery
charging during computer operation, and allows battery dis-
charge for battery gas gauge calibration. It receives control
signals from the notebook computer, monitors input current
from the adapter, provides adapter voltage status to the
notebook system management microcontroller (or embed-
ded controller ), and appropriately drives MOSFET switches
to electrically connect the adapter to the computer.
AIC will allow a system designer to solve various power
management tasks typical for an adapter powered systems
containing a rechargeable battery.
When a notebook computer is being powered from a battery
and the adapter is plugged in, the computer should start
drawing power from the adapter, not from the battery. The
most time efficient charging scenario is when a computer
draws the full rated current from a constant voltage adapter.
The computer uses what it needs to run, and passes all
remaining power on to the battery for charging. The com-
puter should be able to automatically refuse to charge a
battery when powered from an airplane power line. It may be
Typical Delay Time vs. Temperature
5
necessary sometimes to have a computer fully discharging
the battery and then fully recharging it (for battery gas gauge
calibration purposes) while being powered by an AC adapter.
AIC will also allow a computer to prevent backfeeding cur-
rent into an adapter if the adapter is not powered while being
plugged into the computer (some of existing adapters can
draw current from the computer under this conditions for
charging the AC adapter output bulk capacitance from the
computer battery).
While the lowest usable adapter voltage is about 9.5V, that is
V
down to V
erate false readings down to V
readings would be MPS = HIGH, ADAPTER PRESENT =
HIGH, CHARGER PRESENT = HIGH.
AIC determines usable voltage ranges by comparing
V
Electrical Characteristics). AIC detects operating current limit
and leakage current limit into the adapter jack by differential
sensing across current sense resistor R
or scaled down by resistor dividers R1/R3 and R2/R4.
When designing the LM2601 into a system it may be neces-
sary to consider ESD protection requirements for the
adapter jack according to your system design spec.
ADAPTER
ADAPTER
ADAPTER
= 11.7V minus 2.2V hysteresis, AIC is operational
with an internal 2.5V voltage reference (see also
10130905
= 5V. This means that AIC will not gen-
ADAPTER
SENSE
= 5V. Such false
either directly
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