BQ24630 Datasheet, PDF (19/33 Pages) Texas Instruments – Stand-Alone Synchronous Switch-Mode Lithium Phosphate Battery Charger with System Power Selector and Low Iq

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SLUS894 – JANUARY 2010
TEMPERATURE QUALIFICATION
The controller continuously monitors battery temperature by measuring the voltage between the TS pin and
GND. A negative temperature coefficient thermistor (NTC) and an external voltage divider typically 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 battery
temperature is outside of this range, the controller suspends charge and the safety timer 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 battery temperature is outside of this range, the controller suspends
charge and safety timer and waits until the battery temperature is within the V(LTF) to V(HTF) range. If the
battery temperature is between the V(LTF) and the V(COOL) thresholds or between the V(HTF) and V(WARM)
thresholds, charge is automatically reduced to I_CHARGE/8. To avoid early termination during COOL/WARM
condition, set I_TERM ≤ I_CHARGE/10. The controller suspends charge by turning off the PWM charge FETs. Figure 18
and Figure 19 summarizes the operation.
VREF
TEMPERATURE RANGE TO
INITIATE CHARGE
TEMPERATURE RANGE
DURING A CHARGE CYCLE
VREF
CHARGE SUSPENDED
CHARGE SUSPENDED
V_{LTF_}^V_HLYTFS
V_COOL
V_{COOL_HYS}
CHARGE at I_CHARGE/8
CHARGE at I_CHARGE/8
V_LTF
V_COOL
V_WARM
V_{WARM_HYS}
CHARGE at I_CHARGE
CHARGE at I_CHARGE
V_HTF
CHARGE at I_CHARGE/8
CHARGE at I_CHARGE/8
CHARGE SUSPENDED
CHARGE SUSPENDED
GND
Figure 18. TS, Thermistor Sense Thresholds
V_WARM
V_TCO
GND
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