BQ24750_07 Datasheet, PDF (23/38 Pages) Texas Instruments – Host-controlled Multi-chemistry Battery Charger with Integrated System Power Selector and AC Over-Power Protection

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bq24750
SLUS735 – DECEMBER 2006
The DPMDET open-drain output goes low (after a 10-ms delay) when the DPM loop is active to reduce the
battery charge current.
Temperature Qualification
The controller continuously monitors the battery temperature by measuring the voltage between the TS pin and
AGND. In a typical application, a negative-temperature-coefficient thermistor (NTC) and an external voltage
divider develop this voltage. The controller compares this voltage against its internal thresholds to determine if
charging is allowed. To initiate a charge cycle, the battery temperature must be within the V_LTF to V_HTF
thresholds. If the battery temperature is outside of this range, the controller suspends charging and waits until
the battery temperature is within the V_LTF to V_HTF range. During the charge cycle, the battery temperature must
be within the V_LTF to V_TCO thresholds. If the battery temperature is outside this range, the controller suspends
charging and waits until the battery temperature is within the V_LTF to V_HTF range. The controller suspends
charging by turning off the PWM charge FETs. The V_TSDET voltage threshold is used to detect whether a battery
is connected. Figure 32 summarizes the operation.
VREF
VREF
V_LTF
V_LTF-HYS
CHARGE SUSPENDED
TEMPERATURE RANGE
TO INITIATE CHARGE
CHARGE SUSPENDED
V_LTF
V_LTF-HYS
TEMPERATURE RANGE
DURING A CHARGE
CYCLE
V_HTF
CHARGE SUSPENDED
CHARGE SUSPENDED
V_TCO
AGND
AGND
Figure 32. TS, Thermistor Sense Thresholds
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