ACT2801/ACT2801B/ACT2801C
Rev 9, 14-Mar-17
limits.
In a typical application, the TH pin is connected to
the battery pack's thermistor input as shown in
Figure 20. The ACT2801 injects a 60µA current out of
the TH pin into the thermistor, so that the thermistor
resistance is monitored by comparing the voltage at
TH to the internal VTHL and VTHH thresholds of 0.3V
and 1.5V, respectively. When VTH > VTHH or VTH < VTHL
charging and the charge timers are suspended. When
VTH returns to the normal range, charging and the
charge timers resume.
The threshold is given by:
60µA×RNOM×kHOT=0.3V→ RNOM×kHOT=5kΩ
60µA×RNOM×kCOLD=1.5V → RNOM×kCOLD= 25kΩ
where RNOM is the nominal thermistor resistance at
room temperature, and kHOT and kCOLD are the ratios
of the thermistor's resistance at the desired hot and
cold thresholds, respectively.
60µA
+
VTHH
Li+ Battery
Pack
+
-
TH
+
-
NTC
VTHL
–
Figure 20. Battery thermal circuit
Innovative PowerTM
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