ACT2801 datasheet(16/25 Pages) ACTIVE-SEMI

16 / 25 page

Rev 9, 14-Mar-17

Innovative PowerTM

- 16 -

www.active-semi.com

ACT2801/ACT2801B/ACT2801C

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.

VTHH

VTHL

60µA

Li+ Battery

Pack

–

NTC

Figure 20.

Battery thermal circuit

ACT2801 Datasheet(PDF) 16 Page - Active-Semi, Inc