BATTERY PROTECTION IC FOR 1-CELL PACK
Rev.5.3_00
S-8261 Series
Seiko Instruments Inc.
19
4. Overdischarge Status
With power-down function
When the battery voltage falls below the overdischarge detection voltage (V
DL
) during discharging under the normal
status and the detection continues for the overdischarge detection delay time (t
DL
) or longer, the S-8261 Series turns
the discharging control FET off to stop discharging. This status is called the overdischarge status. When the
discharging control FET is turned off, the VM pin voltage is pulled up by the resistor between VM and VDD in the IC
(R
VMD
). When the voltage difference between the VM and VDD then is 1.3 V (typ.) or lower, the current consumption
is reduced to the power-down current consumption (I
PDN
). This status is called the power-down status.
The power-down status is released when a charger is connected and the voltage difference between the VM and
VDD becomes 1.3 V (typ.) or higher. Moreover when the battery voltage becomes the overdischarge detection
voltage (V
DL
) or higher, the S-8261 Series turns the discharging FET on and returns to the normal status.
Without power-down function
When the battery voltage falls below the overdischarge detection voltage (V
DL
) during discharging under the normal
status and the detection continues for the overdischarge detection delay time (t
DL
) or longer, the S-8261 Series turns
the discharging control FET off to stop discharging. This status is called the overdischarge status. When the
discharging control FET is turned off, the VM pin voltage is pulled up by the resistor between VM and VDD in the IC
(R
VMD
).
When the battery voltage becomes the overdischarge detection voltage (V
DL
) or higher, the S-8261 Series turns the
discharging FET on and returns to the normal status.
5. Charger Detection
When a battery in the overdischarge status is connected to a charger and provided that the VM pin voltage is lower
than the charger detection voltage (V
CHA
), the S-8261 Series releases the overdischarge status and turns the
discharging control FET on when the battery voltage becomes equal to or higher than the overdischarge detection
voltage (V
DL
) since the charger detection function works. This action is called charger detection.
When a battery in the overdischarge status is connected to a charger and provided that the VM pin voltage is not
lower than the charger detection voltage (V
CHA
), the S-8261 Series releases the overdischarge status when the
battery voltage reaches the overdischarge detection voltage (V
DL
) + overdischarge hysteresis (V
HD
) or higher.
6. Abnormal Charge Current Detection
If the VM pin voltage falls below the charger detection voltage (V
CHA
) during charging under normal status and it
continues for the overcharge detection delay time (t
CU
) or longer, the charging control FET turns off and charging
stops. This action is called the abnormal charge current detection.
Abnormal charge current detection works when the DO pin voltage is “H” and the VM pin voltage falls below the
charger detection voltage (V
CHA
). Consequently, if an abnormal charge current flows to an over-discharged battery,
the S-8261 Series turns the charging control FET off and stops charging after the battery voltage becomes higher
than the overdischarge detection voltage which make the DO pin voltage “H”, and still after the overcharge detection
delay time (t
CU
) elapses.
Abnormal charge current detection is released when the voltage difference between VM pin and VSS pin becomes
less than charger detection voltage (V
CHA
).
