BQ24090_12 Datasheet, PDF (21/34 Pages) Texas Instruments – 1A, Single-Input, Single Cell Li-Ion and Li-Pol Battery Charger

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bq24095
SLUS968D – JANUARY 2010 – REVISED DECEMBER 2012
Termination
Once the OUT pin goes above VRCH, (reaches voltage regulation) and the current tapers down to the
termination threshold, the CHG pin goes high impedance and a battery detect route is run to determine if the
battery was removed or the battery is full. If the battery is present, the charge current will terminate. If the battery
was removed along with the thermistor, then the TS pin is driven high and the charge enters TTDM. If the battery
was removed and the TS pin is held in the active region, then the battery detect routine will continue until a
battery is inserted.
Battery Detect Routine
The battery detect routine should check for a missing battery while keeping the OUT pin at a useable voltage.
Whenever the battery is missing the CHG pin should be high impedance.
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 threshold, 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.
Refresh Threshold
After termination, if the OUT pin voltage drops to V_RCH (100mV below regulation) then a new charge is initiated,
but the CHG pin remains at a high impedance (off).
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.
Copyright © 2010–2012, Texas Instruments Incorporated
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