BQ24650 Datasheet, PDF (18/33 Pages) Texas Instruments – Synchronous Switch-Mode Battery Charge Controller for Solar Power With Maximum Power Point Tracking

bq24650
SLUSA75 – JULY 2010
www.ti.com
BATTERY DETECTION
For applications with removable battery packs, the bq24650 provides a battery absent detection scheme to
reliably detect insertion or removal of battery packs.
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
No
expired
Yes
Disable 6mA
discharge current
Yes
Battery Present,
Begin Charge
Enable 125mA Charge,
Start 0.5s timer
VFB > VRECH
Yes
Disable 125mA
Charge
0.5s timer
No
expired
No
Yes
Battery Present,
Begin Charge
Battery Absent
Figure 19. Battery Detection Flowchart
Once the device has powered up, a 6-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 (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.
18
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