BQ24618_15 Datasheet, PDF (24/43 Pages) Texas Instruments – System Power Selector and Low

bq24618
SLUSA55B – OCTOBER 2010 – REVISED APRIL 2015
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8.3.23 Battery Detection
For applications with removable battery packs, the bq24618 provides a battery-absent detection scheme to
reliably detect insertion or removal of battery packs.
POR or RECHARGE
Apply 8-mA discharge
current, start 1-s timer
The battery detection routine runs on
power up, or if VFB falls below VRECH
due to removing a battery or
discharging a battery
VFB < VLOWV
No
1-s timer
No
expired
Yes
Disable 8-mA
discharge current
Yes
Battery Present,
Begin Charge
Enable 125-mA Charge,
Start 0.5-s timer
VFB > VRECH
Yes
Disable 125-mA
Charge
0.5-s timer
No
expired
No
Yes
Battery Present,
Begin Charge
Battery Absent
Figure 16. Battery-Detection Flow Chart
Once the device has powered up, an 8-mA discharge current is applied to the SRN terminal. If the battery
voltage falls below the LOWV threshold within 1 second, the discharge source is turned off, and the charger is
turned on at low charge current (125 mA). If the battery voltage rises above the recharge threshold within 500
ms, there is no battery present and the cycle restarts. If either the 500-ms or 1-second timer times out before its
respective threshold is hit, a battery is detected and a charge cycle is initiated.
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