BQ24620 Datasheet, PDF (21/30 Pages) Texas Instruments – Stand-Alone Synchronous Switch-Mode Lithium Phosphate Battery Charger with Low Iq

bq24620
www.ti.com
SLUS893 – MARCH 2010
BATTERY DETECTION
For applications with removable battery packs, bq24620 provides a battery absent detection scheme to reliably
detect insertion or removal of battery packs. CE needs to be HIGH to enable battery detection function.
POR or RECHARGE
Apply 8mA discharge
current, start 1s 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
1s timer
expired
No
Yes
Disable 8mA
discharge current
Yes
Battery Present,
Begin Charge
Enable 125 mA Charge,
Start 0.5s timer
VFB > VRECH
Yes
Disable 125mA
Charge
0.5s timer
No
No
expired
Yes
Battery Present,
Begin Charge
Battery Absent
Figure 15. Battery Detection Flowchart
Once the device has powered up, an 8mA discharge current will be 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 (125mA). If the battery voltage gets up above the recharge threshold within
500ms, there is no battery present and the cycle restarts. If either the 500ms or 1 second timer time out before
the respective thresholds are hit, a battery is detected and a charge cycle is initiated.
Copyright © 2010, Texas Instruments Incorporated
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