Note 5: Adapter Enable input is used to change the state of Disconnect, Direction Sense input is used to change the state of Backfeed.

a.

is initiated at Adapter Enable or Direction Sense.

b.

at Adapter Enable or Direction Sense.

Typical Application

10130903

Notes

1.

R

programmed over current will cause a voltage drop

across R

R

should be used to scale the voltage drop down.

2.

Internal and external circuits associated with Direction

Sense and Backfeed FET pins allow to emulate a Schot-

tky diode functionality with much lower forward voltage

drop and, therefore, with much lower power dissipation.

R2/R4 resistor divider programs the backfeed current

protection threshold. The backfeed FET Q1 turns off

when the backfeed current pulse level causes more than

9 mV (typical value) voltage drop between V

and Direction Sense pin.

3.

Voltage difference (V

be higher than 20mV to reliably isolate the adapter in

case of leakage.

4.

R5 and R6 prevent the FETs from turning on unless

driven by LM2601.

5.

C

mula:

C

6.

T

also the Typical Delay Time vs. Temperature graph.

7.

Pin Master Power Source (MPS) should be connected to

System Management Controller’s (SMC) and battery

packs’ GPIOs. When SMC detects a powered AC

adapter via active signals at Charger Present or Adapter

Present outputs, it asserts Adapter Enable signal and

isolates the battery pack(s). Adapter Enable signal turns

the Disconnect FET on. When the AC adapter is un-

plugged or powered off, SMC enables one of the system

battery packs. The battery packs’ embedded controller

starts driving the logic MPS signal high that turns the

Disconnect FET off.

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