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| BQ24013 Datasheet, PDF (14/21 Pages) Texas Instruments – SINGLE-CHIP, LI-ION CHARGE MANAGEMENT IC FOR HANDHELD APPLICATIONS (bq TINY) | |||
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bq24010, bq24012, bq24013, bq24014
SLUS530F â SEPTEMBER 2002 â REVISED AUGUST 2005
FUNCTIONAL DESCRIPTION
www.ti.com
BATTERY ABSENT DETECTION
For applications with removable battery packs, bqTINY provides a battery absent detection scheme to reliably detect
insertion and/or removal of battery packs.
The voltage at the BAT pin is held above the battery recharge threshold, V(RCH), by the charged battery following
fast charging. When the voltage at the BAT pin falls to the recharge threshold, either by a load on the battery or due
to battery removal, the bqTINY begins a battery absent detection test. This test involves enabling a detection current,
I(DETECT), for a period of t(DETECT) and checking to see if the battery voltage is below the pre-charge threshold,
V(LOWV). Following this, the precharge current, IO(PRECHG) is applied for a period of t(DETECT) and the battery voltage
checked again to be above the recharge threshold. The purpose is to attempt to close a battery pack with an open
protector, if one is connected to the bqTINY. Passing both of the discharge and charging tests indicates a battery
absent fault at the STAT pins. Failure of either test starts a new charge cycle. For the absent battery condition the
voltage on the BAT pin rises and falls between the V(LOWV) and VO(REG) thresholds indefinitely. See Figure 7.
Charge Done
or
Timer Fault
No
VI(BAT) <
V(RCH)
Yes
Enable
I(DETECT) for
t(DETECT)
VI(BAT) <
V(LOWV)
No
Yes
Apply
IO(PRECHG) for
t(DETECT)
VI(BAT) >
No
V(RCH)
Yes
BATTERY
ABSENT
BATTERY
PRESENT
Begin Charge
BATTERY
PRESENT
Begin
Charge
Figure 7. Battery Absent Detection
14
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