bq24030, bq24031, bq24032,
bq24032A, bq24035, bq24038, bq24039
www.ti.com
SLUS618C–AUGUST 2004–REVISED JUNE 2005
V
USB
I
USB
Figure 13. USB Boot-Up Power-Up
Battery Temperature Monitoring
The bqTINY-III continuously monitors battery temperature by measuring the voltage between the TS and VSS
pins. An internal current source 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 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.
PACK+
PACK+
bqTINYIII
bqTINYIII
+
+
PACK−
RT1
I
TS
PACK−
TS
I
TS
TS
NTC
NTC
TEMP
9
9
LTF
LTF
BATTERY
PACK
V
LTF
BATTERY
PACK
V
LTF
RT2
V
HTF
HTF
V
HTF
HTF
UDG−04086
UDG−04085
Figure 14. TS Pin Configuration
Figure 15. TS Pin Thresholds
Battery Pre-Conditioning
During a charge cycle, if the battery voltage is below the V(LOWV) threshold, the bqTINY-III applies a precharge
current, IO(PRECHG), to the battery. This feature revives deeply discharged cells. The resistor connected between
the ISET1 and VSS, RSET, 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.
21
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