S-8252AAA-M6T1U Datasheet, PDF (16/36 Pages) Seiko Instruments Inc – BATTERY PROTECTION IC

BATTERY PROTECTION IC FOR 2-SERIAL-CELL PACK
S-8252 Series
Rev.3.2_00
3. Overdischarge status
When the battery voltage falls below overdischarge detection voltage (V_DL) during discharging in the normal status
and the condition continues for the overdischarge detection delay time (t_DL) or longer, the S-8252 Series turns the
discharging control FET off to stop discharging. This condition is called the overdischarge status.
Under the overdischarge status, the VM pin and VDD pin are shorted by R_VMD in the S-8252 Series. The VM pin is
pulled up by R_VMD.
R_VMS is not connected in the overdischarge status.
3. 1 With power-down function
Under the overdischarge status, when voltage difference between the VM pin and VDD pin is 0.8 V typ. or lower,
the power-down function works and the current consumption is reduced to the current consumption during
power-down (I_PDN). By connecting a battery charger, the power-down function is released when the VM pin
voltage is 0.7 V typ. or lower.
• When a battery is not connected to a charger and the VM pin voltage ≥ 0.7 V typ., the S-8252 Series maintains
the overdischarge status even when the battery voltage reaches V_DU or higher.
• When a battery is connected to a charger and 0.7 V typ. > the VM pin voltage > −0.7 V typ., the battery voltage
reaches V_DU or higher and the S-8252 Series releases the overdischarge status.
• When a battery is connected to a charger and −0.7 V typ. ≥ the VM pin voltage, the battery voltage reaches V_DL
or higher and the S-8252 Series releases the overdischarge status.
3. 2 Without power-down function
The power-down function does not work even when voltage difference between the VM pin and VDD pin is 0.8 V
typ. or lower.
• When a battery is not connected to a charger and the VM pin voltage ≥ 0.7 V typ., the battery voltage reaches
V_DU or higher and the S-8252 Series releases the overdischarge status.
• When a battery is connected to a charger and 0.7 V typ. > the VM pin voltage > −0.7 V typ., the battery voltage
reaches V_DU or higher and the S-8252 Series releases the overdischarge status.
• When a battery is connected to a charger and −0.7 V typ. ≥ the VM pin voltage, the battery voltage reaches V_DL
or higher and the S-8252 Series releases the overdischarge status.
4. Discharge overcurrent status (Discharge overcurrent, load short-circuiting)
When a battery in the normal status is in the status where the voltage of the VM pin is equal to or higher than V_DIOV
because the discharge current is equal to or higher than the specified value and the status lasts for the discharge
overcurrent detection delay time (t_DIOV) or longer, the discharge control FET is turned off and discharging is stopped.
This status is called the discharge overcurrent status.
In the discharge overcurrent status, the VM pin and VSS pin are shorted by the R_VMS in the S-8252 Series. However,
the voltage of the VM pin is at the V_DD potential due to the load as long as the load is connected. When the load is
disconnected, the VM pin returns to the V_SS potential.
If the voltage at the VM pin returns to V_DIOV or lower, the S-8252 Series releases the discharge overcurrent status.
R_VMD is not connected in the discharge overcurrent detection status.
5. Charge overcurrent status (with charge overcurrent detection function)
When a battery in the normal status is in the status where the voltage of the VM pin is equal to or lower than V_CIOV
because the charge current is equal to or higher than the specified value and the status lasts for the charge
overcurrent detection delay time (t_CIOV) or longer, the charge control FET is turned off and charging is stopped. This
status is called the charge overcurrent status.
The S-8252 Series releases the charge overcurrent status when the voltage at the VM pin returns to V_CIOV or higher
by removing the charger.
The charge overcurrent detection function does not work in the overdischarge status.
R_VMD and R_VMS are not connected in the charge overcurrent detection status.
6. Abnormal charge current status (without charge overcurrent detection function)
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 status.
Abnormal charge current status is released when the voltage difference between VM pin and VSS pin becomes less
than charger detection voltage (V_CHA).
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