BQ24200DGNG4 Datasheet, PDF (8/20 Pages) Texas Instruments – SINGLE-CHIP LI-ION AND LI-POL CHARGE MANAGEMENT IC FOR CURRENT-LIMITED APPLICATIONS

bq24200, bq24201
bq24202, bq24203
bq24204, bq24205
SLUS501C – OCTOBER 2001 – REVISED MARCH 2008
APPLICATION INFORMATION
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Figure 5. Low Dropout Single-Cell Li-Ion/Li-Pol Charger
FUNCTIONAL DESCRIPTION
The bq2420x supports a precision Li-Ion or Li-Pol charging system suitable for single-cells with either coke or
graphite anodes. Figure 5 shows an application schematic and Figure 6 shows the typical charge profile.
TEMPERATURE QUALIFICATION (bq24200 and bq24202 only)
The bq24200 and bq24201 continuously monitors battery temperature by measuring the voltage between the TS
and VSS pins. A negative- or a positive-temperature coefficient thermistor (NTC, PTC) and an external voltage
divider typically develop this voltage (see Figure 5). The bq24200 and bq24201 compare this voltage against the
internal V_(TS1) and V_(TS2) thresholds to determine if charging is allowed (see Figure 7). The temperature sensing
circuit is immune to any fluctuation in Vcc since both the external voltage divider and the internal thresholds are
referenced to Vcc.
Once a temperature outside the V_(TS1) and V_(TS2) thresholds is detected the bq24200 and bq24201 immediately
suspend the charge. The bq24200 and bq24201 suspend the charge by turning off the power FET and holding
the timer value (i.e., timers are NOT reset). Charge is resumed when the temperature returns to the normal
range.
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