BQ25100_15 Datasheet, PDF (20/32 Pages) Texas Instruments – bq2510x 250-mA Single Cell Li-Ion Battery Chargers, 1-mA Termination, 75-nA Battery Leakage

bq25100, bq25101, bq25100A, bq25100H, bq25101H, bq25100L
SLUSBV8C – AUGUST 2014 – REVISED NOVEMBER 2014
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Device Functional Modes (continued)
8.4.5 Termination and Timer Disable Mode (TTDM) - TS Pin High
The battery charger is in TTDM when the TS pin goes high from removing the thermistor (removing battery
pack/floating the TS pin) or by pulling the TS pin up to the TTDM threshold.
When entering TTDM, the 10 hour safety timer is held in reset and termination is disabled. A battery detect
routine is run to see if the battery was removed or not. For bq25101/1H, if the battery was removed then the
CHG pin will go to its high impedance state if not already there. If a battery is detected the CHG pin does not
change states until the current tapers to the termination threshold, where the CHG pin goes to its high
impedance state if not already there (the regulated output will remain on).
The charging profile does not change (still has pre-charge, fast-charge constant current and constant voltage
modes). This implies the battery is still charged safely and the current is allowed to taper to zero.
When coming out of TTDM, the battery detect routine is run and if a battery is detected, then a new charge cycle
begins.
If TTDM is not desired upon removing the battery with the thermistor, one can add a 237-kΩ resistor between TS
and V_SS to disable TTDM. This keeps the current source from driving the TS pin into TTDM. This creates ≉0.1°C
error at hot and a ≉3°C error at cold.
8.4.6 Battery Detect Routine
The battery detect routine should check for a missing battery while keeping the OUT pin at a useable voltage.
The battery detect routine is run when entering and exiting TTDM to verify if battery is present, or run all the time
if battery is missing and not in TTDM. On power-up, if battery voltage is greater than V_RCH thereshold, a battery
detect routine is run to determine if a battery is present.
The battery detect routine is disabled while the IC is in TTDM, or has a TS fault. See Figure 23 for the Battery
Detect Flow Diagram.
8.4.7 Refresh Threshold
After termination, if the OUT pin voltage drops to V_RCH (100mV below regulation) then a new charge is initiated.
8.4.8 Starting a Charge on a Full Battery
The termination threshold is raised by ≉14% for the first minute of a charge cycle so if a full battery is removed
and reinserted or a new charge cycle is initiated, that the new charge terminates (less than 1 minute). Batteries
that have relaxed many hours may take several minutes to taper to the termination threshold and terminate
charge.
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