S-8262AAA-I8T1U Datasheet, PDF (16/36 Pages) Seiko Instruments Inc – BATTERY PROTECTION IC

BATTERY PROTECTION IC FOR 2-SERIAL-CELL PACK
S-8262A Series
Rev.1.0_02
 Operation
Remark Refer to " Battery Protection IC Connection Example".
1. Normal status
The S-8262A Series monitors the voltage of the battery connected between the VDD pin and VSS pin and the
voltage difference between the VM pin and VSS pin to control charging and discharging. When the battery voltage
is in the range from overdischarge detection voltage (V_DL) to overcharge detection voltage (V_CU), and the VM pin
voltage is in the range from the charge overcurrent detection voltage (V_CIOV) to discharge overcurrent 1 detection
voltage (V_DIOV1), the S-8262A Series turns both the charge and discharge control FETs on. This condition is called
the normal status, and in this condition charging and discharging can be carried out freely. In the normal status the
AO pin output becomes "High-Z". The resistance (R_VMD) between the VM pin and VDD pin, and the resistance
(R_VMS) between the VM pin and VSS pin are not connected in the normal status.
Caution When the battery is connected for the first time, discharging may not be enabled. In this case,
Short the VM pin and VSS pin, or
Set the VM pin’s voltage at the level of V_CIOV or more and V_DIOV1 or less by connecting the charger
The IC returns to the normal status.
2. Overcharge status
When the battery voltage becomes higher than V_CU during charging in the normal status and detection continues
for the overcharge alarm detection delay time (t_AU) or longer, the AO pin output becomes 'L". Moreover, when the
detection continues for the detection delay time (t_CU) or longer, the S-8262A Series turns the charge control FET off
to stop charging. This condition is called the overcharge status. In the overcharge status the AO pin output
maintains "L", and R_VMD and R_VMS are not connected.
When the AO pin output is "L", the AO pin output becomes "High-Z" after the overcharge alarm release delay time
(t_AL) if the battery voltage decreases and falls below V_CU during t_CU.
The overcharge status is released in the following two cases ((1) and (2)). The AO pin output becomes "High-Z"
simultaneously with the release of the overcharge status.
(1) In the case that the VM pin voltage is lower than V_DIOV2, the S-8262A Series releases the overcharge status
when the battery voltage falls below V_CL.
(2) In the case that the VM pin voltage is higher than or equal to V_DIOV2, the S-8262A Series releases the
overcharge status when the battery voltage falls below V_CU.
When the discharge is started by connecting a load after the overcharge detection, the VM pin voltage rises
more than the voltage at VSS pin due to the V_f voltage of the parasitic diode, because the discharge current
flows through the parasitic diode in the charge control FET. If this VM pin voltage is higher than or equal to
V_DIOV2, the S-8262A Series releases the overcharge status when the battery voltage is lower than or equal to
V_CU.
Caution 1.
2.
If the battery is charged to a voltage higher than V_CU and the battery voltage does not fall to
V_CU or lower even when a heavy load is connected, discharge overcurrent 1 detection,
discharge overcurrent 2 detection and load short-circuiting detection do not function until the
battery voltage falls below V_CU. However, since an actual battery has an internal impedance of
tens of mΩ, the battery voltage drops immediately after a heavy load that causes overcurrent
is connected, and discharge overcurrent 1 detection, discharge overcurrent 2 detection and
load short-circuiting detection function.
If a charger is connected after the overcharge detection, the overcharge status is not released
even when the battery voltage falls below V_CL. The S-8262A Series releases the charge
overcurrent status when the voltage at the VM pin returns to V_CIOV or higher by removing the
charger.
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