ACT2803
Rev 1, May-12-2016
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.
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.
INDICATION PATTERN
RPT
#
Conventional
1a
4kΩ
Always On In Discharge
Conventional
1b
2
12kΩ
24kΩ
40kΩ
56kΩ
5s Indication in Discharge
Breathing
5s Indication in Discharge
Bottom Charging
3
5s Indication in Discharge
Circulating
4
5s Indication in Discharge
Below shows 4 LED indication patterns.
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 .
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.
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
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