Datasheet

bq24725A

www.ti.com

SLUSAL0 –SEPTEMBER 2011

external capacitor of ACFET must be carefully selected. The larger the Cgs and Cgd capacitance, the slower turn

on of ACFET will be and less inrush current of adapter. However, if Cgs or Cgd is too large, the ACDRV-CMSRC

voltage may still go low after the 20ms turn on time window is expired. To make sure ACFET will not be turned

on when adapter is hot plugged in, the Cgs value should be 20 times or higher than Cgd. The most cost effective

way to reduce adapter in-rush current is to minimize system total capacitance.

Battery LEARN Cycle

A battery LEARN cycle can be activated via SMBus command (ChargeOption() bit[6]=1 enable LEARN cycle,

bit[6]=0 disable LEARN cycle). When LEARN is enabled with ACFET/RBFET connected, the system power

selector logic is over-driven to switch to battery by turning off ACFET/RBFET and turning on BATFET. LEARN

function allows the battery to discharge in order to calibrate the battery gas gauge over a complete

discharge/charge cycle. The controller automatically exits LEARN cycle when the battery voltage is below battery

depletion threshold, and the system switches back to adapter input by turning off BATFET and turning on

ACFET/RBFET. After LEARN cycle, the LEARN bit is automatically reset to 0. The battery depletion threshold

can be set to 59.19%, 62.65%, 66.55%, and 70.97% of voltage regulation level via SMBus command

(ChargeOption() bit[12:11]).

Product Folder Link(s) :bq24725A