ACT2803 datasheet(15/22 Pages) ACTIVE-SEMI

15 / 22 page

Rev 1, May-12-2016

Innovative PowerTM

- 15 -

www.active-semi.com

ACT2803

APPLICATIONS INFORMATION

In charge mode, the battery charger provides bias

current to balance battery charge. The balance

resistor is either connected to upper battery or

lower battery depending on which battery voltage is

higher. The balance resistor is connected in parallel

with one battery that is higher than the other

battery. For extremely unbalanced 2S batteries, the

charger takes a few cycles to make two battery

voltage balanced. For some applications, like

removable dual cell batteries, a charger is required

to balance dual cells in one charge cycle. In this

case, the circuit shown in Figure 5 is recommended.

The balance current through the 22 Ohm

resistor

needs to be higher than EOC current

threshold.

Figure 5: Cell balance

LED Indication

ACT2803 is designed 5 levels of PT pin voltage into

5 application patterns. A resistor is connected from

PT pin to ground and the voltage at PT pin

programs the LED indication patterns shown in

Figure 6 .

Figure 6: LED Indication

In discharge mode, when battery voltage goes

below LED1 threshold, LED1 starts flashing until

Buck (discharge mode) turns off due to either light

load or Buck UVLO. The flash frequencies for all

the LEDs are 0.5Hz with 1s on and 1s off.

In HZ mode, when PB is pressed for 40ms, Buck

turns on. If VBAT<LED1, LED1 starts flashing until

Buck turns off.

Conventional indication patterns could behave to

have two application. Setting RPT=4kΩ to have

“Always On”, setting RPT=12kΩ to have “5s

Indication”. The behaviors for both setting are same

in charge mode.

See below table for more information.

Below shows 4 LED indication patterns.

LED1-4 Refreshing Cycle

Every time when VIN is plugged in or a PB is

pushed, LED1, 2, 3, 4 turns on sequentially at 0.5s

interval, like a LED scanning, and then goes into

corresponding mode defined by PT pin.

LED1-4 Fault Alarm Signal

At fault conditions, actions are taken. In the

meantime, all the 4 LEDs turn on/off with 0.5s on

and 0.5s off for 10 seconds to send alarm signal

out. The fault conditions include battery OVP, UVP,

OTP.

PCB Board Layout Guidance

When laying out the printed circuit board, the

following checklist should be used to ensure proper

operation of the IC.

1. Arrange the power components to reduce the

AC loop area.

INDICATION PATTERN

RPT

Conventional

Always On In Discharge

4kΩ

Conventional

5s Indication in Discharge

12kΩ

Breathing

5s Indication in Discharge

24kΩ

Bottom Charging

5s Indication in Discharge

40kΩ

Circulating

5s Indication in Discharge

56kΩ

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