S-8211CDO-I6T1U datasheet(21/43 Pages) ABLIC

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BATTERY PROTECTION IC FOR 1-CELL PACK

Rev.7.7_03

S-8211C Series



Operation

Remark Refer to " Battery Protection IC Connection Example".

1. Normal status

The S-8211C 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 (VDL) to overcharge detection voltage (VCU), and the VM pin

voltage is in the range from the charge overcurrent detection voltage (VCIOV) to discharge overcurrent detection

voltage (VDIOV), the S-8211C Series turns both the charging and discharging control FETs on. This condition is called

the normal status, and in this condition charging and discharging can be carried out freely.

The resistance (RVMD) between the VM pin and VDD pin, and the resistance (RVMS) 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 the charge overcurrent detection

voltage (VCIOV) or more and the discharge overcurrent detection voltage (VDIOV) or less by

connecting the charger. The S-8211C Series then returns to the normal status.

2. Overcharge status

When the battery voltage becomes higher than overcharge detection voltage (VCU) during charging in the normal

status and detection continues for the overcharge detection delay time (tCU) or longer, the S-8211C Series turns the

charging control FET off to stop charging. This condition is called the overcharge status.

The resistance (RVMD) between the VM pin and VDD pin, and the resistance (RVMS) between the VM pin and VSS pin

are not connected in the overcharge status.

The overcharge status is released in the following two cases ( (1) and (2) ).

(1) In the case that the VM pin voltage is higher than or equal to the charge overcurrent detection voltage (VCIOV),

and is lower than the discharge overcurrent detection voltage (VDIOV), the S-8211C Series releases the

overcharge status when the battery voltage falls below the overcharge release voltage (VCL).

(2) In the case that the VM pin voltage is higher than or equal to the discharge overcurrent detection voltage (VDIOV),

the S-8211C Series releases the overcharge status when the battery voltage falls below the overcharge

detection voltage (VCU).

The discharge is started by connecting a load after the overcharge detection, the VM pin voltage rises more than

the VSS pin voltage due to the Vf voltage of the parasitic diode, because the discharge current flows through the

parasitic diode in the charging control FET. If this VM pin voltage is higher than or equal to the discharge

overcurrent detection voltage (VDIOV), the S-8211C Series releases the overcharge status when the battery voltage

is lower than or equal to the overcharge detection voltage (VCU).

For the actual application boards, changing the battery voltage and the charger voltage simultaneously enables to

measure the overcharge release voltage (VCL). In this case, the charger is always necessary to have the

equivalent voltage level to the battery voltage. The charger keeps VM pin voltage higher than or equal to the

charge overcurrent detection voltage (VCIOV) and lower than or equal to the discharge overcurrent detection

voltage (VDIOV). The S-8211C Series releases the overcharge status when the battery voltage falls below the

overcharge release voltage (VCL).

Caution 1. If the battery is charged to a voltage higher than overcharge detection voltage (VCU) and the

battery voltage does not fall below overcharge detection voltage (VCU) even when a heavy load is

connected, discharge overcurrent detection and load short-circuiting detection do not function

until the battery voltage falls below overcharge detection voltage (VCU). Since an actual battery

has an internal impedance of tens of m

, the battery voltage drops immediately after a heavy

load that causes overcurrent is connected, and discharge overcurrent detection and load short-

circuiting detection function.

2. When a charger is connected after overcharge detection, the overcharge status is not released

even if the battery voltage is below overcharge release voltage (VCL). The overcharge status is

released when the VM pin voltage goes over the charge overcurrent detection voltage (VCIOV) by

removing the charger.

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