ACE4702

2 Cell Li-ion Battery Charger IC

VER 1.1

8

Where:

 I



Rext is the external resistance from EOC pin to GND in Ω. Rext can not be great than 100KΩ,

otherwise the charging may not be terminated correctly.

 R

CS

is the current sense resistance between CSP pin and BAT pin in Ω

When Rext=0Ω, the minimum I

When Rext=100KΩ, the maximum I

Automatic Battery Recharge

After the charge cycle is completed and both the battery and the input power supply (wall adapter) are

still Connected, a new charge cycle will begin if the battery voltage drops below 4V/cell due to

self-discharge or external loading. This will keep the battery capacity at more than 80% at all times

without manually restarting the charge cycle.

Battery Temperature Monitoring

A negative temperature coefficient (NTC) thermistor located close to the battery pack can be used to

monitor battery temperature and will not allow charging unless the battery temperature is within an

acceptable range.

Connect a 10kΩ thermistor from the TEMP pin to ground. Internally, for hot

temperature, the low voltage threshold is set at 175mV which is equal to 50℃(RNTC≈

3.5kΩ). For cold

temperature, the high voltage threshold is set at 1.61V which is equal to 0℃(RNTC≈

32kΩ) with 50uA of

pull-up current.

Once the temperature is outside the window, the charge cycle will be suspended, and the charge cycle

resumes if the temperature is back to the acceptable range.

The TEMP pin’s pull up current is about 50uA, so the NTC thermistor’s resistance should be 10kΩ at 25

℃,

about 3.5kΩ at hot temperature threshold, and about 32kΩ at cold temperature threshold. The NTC

thermistor such as TH11-

3H103F, MF52(10 kΩ), QWX-103 and NCP18XH103F03RB can work well with

ACE4702. The above mentioned part numbers are for reference only, the users can select the right NTC

thermistor part number based on their requirements.

If battery temperature monitoring function is not needed, just connect a 10KΩ resistor from TEMP pin to

GND.

Status Indication

The ACE4702 has 2 open-drain status outputs: CHRG and DONE. CHRG is pulled low when the

charger is in charging status, otherwise CHRG becomes high impedance. DONE is pulled low if the

charger is in charge termination status, otherwise DONE becomes high impedance.

When the battery is not present, the charger charges the output capacitor to the float-charge voltage.