BATTERY PROTECTION IC FOR SINGLE-CELL PACK
S-8261 Series
Rev.1.9_00
4. Overdischarge Condition
When the battery voltage falls below the overdischarge detection voltage (VDL) during discharging under
the normal condition and the detection continues for the overdischarge detection delay time (tDL) or
longer, the S-8261 Series turns the discharging control FET off to stop discharging. This condition is
called the overdischarge condition. 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 (RVMD). 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 (IPDN). This condition is called the power-down condition.
The power-down condition 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 (VDL) or higher, the S-8261 Series turns the discharging FET on and
returns to the normal condition.
5. Charger Detection
When a battery in the overdischarge condition is connected to a charger and provided that the VM pin
voltage is lower than the charger detection voltage (VCHA), the S-8261 Series releases the overdischarge
condition and turns the discharging control FET on when the battery voltage becomes equal to or higher
than the overdischarge detection voltage (VDL) since the charger detection function works. This action is
called charger detection.
When a battery in the overdischarge condition is connected to a charger and provided that the VM pin
voltage is not lower than the charger detection voltage (VCHA), the S-8261 Series releases the
overdischarge condition when the battery voltage reaches the overdischarge detection voltage (VDL) +
overdischarge hysteresis (VHD) or higher.
6. Abnormal Charge Current Detection
If the VM pin voltage falls below the charger detection voltage (VCHA) during charging under normal
condition and it continues for the overcharge detection delay time (tCU) 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 (VCHA). 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 (tCU) elapses.
Abnormal charge current detection is released when the voltage difference between VM pin and VSS pin
becomes less than charger detection voltage (VCHA).
Seiko Instruments Inc.
19
SII [ SEIKO INSTRUMENTS INC ]
