ACT2813/ACT2813C
Rev 2, 19-May-15
Figure 2:
ACT2813C System Operation Flow Chart
at a reduced current, 10% of the programmed
maximum fast charge constant current. Once VBAT
reaches the precondition threshold voltage the state
machine jumps to the fast charge state.
Latch-Off
ACT2813/ACT2813C has latch off function. If
discharging stops due to battery cut-off, and latch
off will be triggered, it would prevent battery from
discharging again, latch-off is released when input
power is recycled.
Fast Charge
If battery voltage is above preconditioning
threshold, buck converter charges battery with
constant current. In fast charge state, the ACT2813/
ACT2813C charges at the current set by the
external resistor connected at the ICST pin. During
a normal charge cycle fast charge continues in CC
mode until VBAT reaches the charge termination
voltage, at which point the ACT2813/ACT2813C
charges in top off state.
Switching Battery Charger
ACT2813/ACT2813C is configured in charge mode
(buck mode) when VIN is valid. In this mode, the
battery is charged with preconditioning, fast charge,
top-off and end of charge (EOC). The typical charge
management is shown in Figure 3 and Figure 4.
CC/CV Regulation Loop
Top Off
There are CC/CV regulation loops built in ACT2813/
ACT2813C, which regulates either current or
voltage as necessary to ensure fast and safe
charging of the battery. In a normal charge cycle,
this loop regulates the current to the value set by
the external resistor at the ICST pin. Charging
continues at this current until the battery cell voltage
reaches the termination voltage. At this point the
CV loop takes over, and charge current is allowed
to decrease as necessary to maintain charging at
the termination voltage.
With the battery voltage approaches the EOC
voltage, charge current decreases as charging
continues. In the top off state, the cell is charged in
constant voltage (CV) mode. During a normal
charging cycle charging proceeds until the charge
current decreases below the end of charge (EOC)
threshold, defined as 15% of fast charge current.
When this happens, the state machine terminates
the charge cycle and jumps to the EOC state.
End of Charge
Precondition Charge
When charges current decreases to 15% of set fast
charge current, the buck converter goes into end of
charge mode and keep monitoring the battery
voltage.
A new charging cycle begins with the precondition
state, and operation continues in this state until VBAT
exceeds the precondition threshold voltage. When
operating in precondition state, the cell is charged
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