ACT8941A datasheet(40/42 Pages) ACTIVE-SEMI

40 / 42 page

ACT8941A

Rev 0, 12-Mar-13

- 40 -

www.active-semi.com

ActivePMU

TM and ActivePathTM are trademarks of Active-Semi.

I2CTM is a trademark of NXP.

Innovative PowerTM

Active-Semi Proprietary―For Authorized Recipients and Customers

102μA (typ) current into the thermistor (via the TH

pin) and sensing the voltage at TH. The voltage at

TH is continuously monitored, and charging is

suspended if the voltage at TH exceeds either of

the internal VTHH and VTHL thresholds of 0.5V and

2.51V, respectively.

The net resistance (from TH to GA) required to

cross the thresholds are given by:

102μA × RNOM × kHOT = 0.5V → RNOM × kHOT

≈ 5kΩ

102μA × RNOM × kCOLD = 2.51V → RNOM ×

kCOLD ≈ 25kΩ

where RNOM is the nominal thermistor resistance

at room temperature, and kHOT and kCOLD

represent the ratios of the thermistor's resistance at

the desired hot and cold thresholds, respectively, to

the resistance at 25°C.

Battery Temperature Interrupts

In order to ease detecting the status of the battery

temperature, the charger features the ability to

generate interrupts based upon the status of the

battery temperature. Set the TEMPOUT[ ] bit to 1

and TEMPSTAT[ ] bit to 1 to generate an interrupt

when battery temperature goes out of the valid

temperature range. Set the TEMPIN[ ] bit to 1 and

TEMPSTAT[ ] bit to 1 to generate an interrupt when

battery temperature returns to the valid range.

TEMPDAT[ ] indicates the status of the battery

temperature. A value of

1 indicates the battery

temperature is inside of the valid range, a value of 0

indicates the battery is outside of the valid range.

When an interrupt is generated by the battery

temperature event, reading the TEMPSTAT[ ]

returns a value of 1. TEMPSTAT[ ] is automatically

cleared to 0 upon reading. When no interrupt is

generated by the battery temperature event,

reading the TEMPSTAT[ ] returns a value of 0.

Figure 6:

Simple Configuration

ACT8941A

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