5/21
XC6802
Series
■OPERATIONAL EXPLANATION
<Charge Cycle>
If the BAT pin voltage is less than trickle voltage (TYP. 2.9V), the charger enters trickle charge mode. In this mode, a safe
battery charge is possible because approximately only 1/10 of the charge current which was set by the I
SEN
pin, is supplied to
the battery. When the BAT pin voltage rises above the trickle voltage, the charger enters constant-current mode (CC mode)
and the battery is charged by the programmed charge current. When the BAT pin voltage reaches 4.2V, the charger enters
constant-voltage mode (CV mode) automatically. After this, the charge current starts to drop and when it reaches a level
which is 1/10 of the programmed charge current, the charge terminates.
<Setting Charge Current>
The charge current can be set by connecting a resistor between the I
SEN
pin and the V
SS
pin. The battery charge current, I
BAT
,
is 1000 times the current out of the I
SEN
pin. Therefore, the charge current, I
BAT
, is calculated by the following equations:
I
BAT
= (V
ISEN
/ R
SEN
) x 1000 (V
ISEN
= 1.0V (TYP.): Current sense pin voltage)
However I
BAT
≦800mA (SOT-25, SOT-89-5, and USP-6C), I
BAT
≦500mA (USP-6EL)
<Charge Termination>
The battery charge is terminated when the charge current decreases to 1/10
of the full charging level after the battery pin
voltage reaches a float voltage. An internal comparator monitors the I
SEN
pin voltage to detect the charge termination. When
the comparator monitors the I
SEN
pin voltage is less than 100mV (charge termination detect)
(*1)
for 1ms TYP. (charge
termination detect time), the IC enters stand-by mode. A driver transistor turns off during the stand-by mode. In this state, a
failure detection circuit and a monitoring circuit of the battery pin voltage operates.
(*1)
The detect after charging completed: I
SEN
pin voltage should be less than 100mV.
<Automatic Recharge>
In stand-by mode battery voltage falls. When the voltage level at the battery pin drops to recharge battery threshold voltage
(TYP. 4.05V) or less, the charge cycle automatically re-starts after a delay of (TYP. 2ms). As such, no external activation
control is needed.
Charge Cycle
(Charge Main Routine)
Trickle Charge
Constant-Current Charge (CC)
Constant-Voltage Charge (CV)
Yes
Keeping the charge state
during a charge termination
detect time (1ms)
Charge Termination
(Stand-by Mode)
Yes
Keeping the stand-by mode
during a recharge time
(2ms)
Failure Detection
Input Voltage Monitor (UVLO)
Manual Shut-down V
IN
-BAT Voltage Monitor
Charge Cycle Charge Cycle Charge Cycle
Shut-down Shut-down Shut-down
