BQ24030_07 Datasheet, PDF (21/38 Pages) Texas Instruments – SINGLE-CHIP CHARGE AND SYSTEM POWER-PATH MANAGEMENT IC (bqTINY)

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bq24030, bq24031, bq24032A
bq24035, bq24038
SLUS618F – AUGUST 2004 – REVISED NOVEMBER 2006
V_USB
I_USB
Figure 13. USB Boot-Up Power-Up
Battery Temperature Monitoring
The bqTINY™ III-series continuously monitors battery temperature by measuring the voltage between the TS
and VSS pins. An internal current source (I_(TS) = 100 µA, typical) provides the bias for most common 10-kΩ
negative-temperature coefficient thermistors (NTC) (see Figure 14). The device compares the voltage on the TS
pin against the internal V_(LTF) , and V_(HTF) thresholds (0.5 V and 2.5 V, respectively are typical) to determine if
charging is allowed. Once a temperature outside the V_(LTF) and V_(HTF) thresholds is detected, the device
immediately suspends the charge. The device suspends 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.
The allowed temperature range for 103AT-type thermistor is 0°C to 45°C. However, the user may increase the
range by adding two external resistors. See Figure 15.
bqTINYIII
LTF
HTF
V_LTF
V_HTF
PACK+
I_TS
PACK−
TS
9
+
NTC
BATTERY
PACK
UDG−04085
Figure 14. TS Pin Configuration
bqTINYIII
LTF
HTF
V_LTF
V_HTF
PACK+
+
I_TS
PACK−
TS
9
RT1 _TEMP
NTC
BATTERY
RT2
PACK
UDG−04086
Figure 15. TS Pin Thresholds
Battery Pre-Conditioning
During a charge cycle, if the battery voltage is below the V_(LOWV) threshold (3.0 V, typical), the bqTINY III-series
applies a precharge current, I_O(PRECHG), to the battery. This feature revives deeply discharged cells. The resistor
connected between the ISET1 and VSS, R_SET, determines the precharge rate. The V_(PRECHG) and
K_(SET) parameters are specified in the specifications table. Note that this applies to both AC and USB charging.
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