6/8
XC6802
Series
■
OPERATIONAL EXPLANATION (Continued)
<Charge Condition Status>
The /CHG pin constantly monitors the charge states classified as below:
●
Strong pull-down: I
/CHG
=10mA (TYP.) in a charge cycle,
●
Weak pull-down: I
/CHG
=20
μ
A (TYP.) in a stand-by mode,
●
High impedance: in shutdown mode.
<Connection of Shorted BAT Pin>
Even if the BAT pin is shorted to the V
SS
, a trickle charge mode starts to operate for protecting the IC from destruction caused
by over current.
<Undervoltage Lockout (UVLO)>
The UVLO circuit keeps the charger in shut-down mode until the input voltage, V
IN
, rises more than the UVLO voltage.
Moreover, in order to protect the battery charger, the UVLO circuit keeps the charger in shut-down mode when a voltage
between the input pin voltage and BAT pin voltage falls to less than 30mV. The charge will not restart until the voltage
between the input pin voltage and BAT pin voltage rises more than 100mV. During the shut-down mode, the driver transistor
turns off but a failure detection circuit operates, and supply current is reduced to 5
μ
A.
<Soft-Start Function>
To protect against inrush current from the input to the battery, soft-start time is set in the circuit optimally (100
μ
sec, TYP.).
<Manual Shut-Down>
During the charge cycle, the IC can be shifted to the shut-down mode by floating the I
SEN
pin. For this, a drain current to the
battery is reduced to less than 2
μ
A and a shut-down current of the IC is reduced to less than 5
μ
A. A new charge cycle starts
when reconnecting the current sense resistor.
<Opened BAT Pin>
When the BAT pin is left open, the IC needs to be shut-down once after monitoring the CHG pin by a microprocessor etc and
keeping the I
SEN
pin in H level.
<Backflow Prevention Between the BAT Pin and the VIN Pin>
A backflow prevention circuit protects against current flowing from the BAT pin to the V
IN
pin even the BAT pin voltage is higher
than the V
IN
pin voltage.