ACE4702 datasheet(6/15 Pages) ACE

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ACE4702

2 Cell Li-ion Battery Charger IC

VER 1.1

DRV Pin

VDRV High (VCC－VDRV)

IDRV＝-10mA

VDRV Low (VCC－VDRV)

IDRV＝0mA

5.8

Rise Time

Cload＝2nF, 10% to

90%

Fall Time

Cload＝2nF, 90% to

10%

Note 1: VOC is the regulation voltage at BAT pin in constant voltage mode

Detailed Description

The ACE4702 is a constant current, constant voltage Li-Ion battery charger controller that adopts PWM

step-down (buck) switching architecture. The charge current is set by an external sense resistor (RCS)

across the CSP and BAT pins. The final battery regulation voltage in constant voltage mode is internally

set to 8.4V for ACE4702 with 1% accuracy.

A charge cycle begins when the voltage at the VCC pin rises above the UVLO level and is greater than

the battery voltage by VSLPR. At the beginning of the charge cycle, if the battery voltage is less than 5.6V,

the charger goes into trickle charge mode. The trickle charge current is internally set to 15%(Typical) of

the full-scale current. When the battery voltage exceeds 5.6V, the charge goes into full-scale constant

current charge mode. In constant current mode, the charge current is set by the external sense resistor

RCS and an internal 200mV reference, so the charge current equals to 200mV/Rcs. When the battery

voltage approaches the regulation voltage, the charger goes into constant voltage mode, and the charge

current will start to decrease When the charge current drops to a level that is set by the resistor at EOC

pin, the charger cycle is terminated, the DRV pin is pulled up to VCC, and an internal comparator turns off

the internal pull-down N-channel MOSFET at the CHRG pin to indicate that the charge cycle is terminated.

During the charge cycle termination status, another internal pull-down N-channel MOSFET at the DONE

pin is turned on to indicated the termination status.

To restart the charge cycle, just remove and reapply the input voltage. Also, a new charge cycle will

begin if the battery voltage drops below the recharge threshold voltage of 4V/cell.

When the input voltage is not present, the charger goes into sleep mode.

A 10kΩ NTC (negative temperature coefficient) thermistor can be connected from the TEMP pin to

ground for battery temperature qualification. The charge cycle is suspended If the battery temperature is

outside of the acceptable range.

An overvoltage comparator guards against voltage transient overshoots (>8% of regulation voltage). In

this case, P-channel MOSFET is turned off until the overvoltage condition is cleared. This feature is useful

for battery load dump or sudden removal of battery.

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