BATTERY PROTECTION IC WITH ALARM FUNCTION FOR 1-CELL PACK

Rev.1.0_00

S-82T1A Series

17



Operation

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

1.

Normal status

This IC monitors the voltage of the battery connected between VDD pin and VSS pin, the voltage between VINI pin and

VSS pin to control charging and discharging. When the battery voltage is in the range from overdischarge detection

voltage (VDL) to alarm status detection voltage (VAU), and the VINI pin voltage is in the range from charge overcurrent

detection voltage (VCIOV) to discharge overcurrent 1 detection voltage (VDIOV1), both charge and discharge control FETs

are turned on. This status is called the normal status, and in this condition charging and discharging can be carried out

freely.

The resistance between VDD pin and VM pin (RVMD), and the resistance between VM pin and VSS pin (RVMS) are not

connected in the normal status.

Caution After the battery is connected, discharging may not be carried out. In this case, this IC returns to the

normal status by connecting a charger.

2.

Overcharge status

2. 1

VCL

≠ VCU (Product in which overcharge release voltage differs from overcharge detection voltage)

When the battery voltage becomes higher than VCU during charging in the normal status and the condition continues

for the overcharge detection delay time (tCU) or longer, the charge control FET is turned off and charging is stopped.

This status is called the overcharge status.

The overcharge status is released in the following two cases.

(1) In the case that the VM pin voltage is lower than 0.35 V typ., this IC releases the overcharge status when the

battery voltage falls below overcharge release voltage (VCL).

(2) In the case that the VM pin voltage is equal to or higher than 0.35 V typ., this IC releases the overcharge status

when the battery voltage falls below VCU.

When the discharge is started by connecting a load after the overcharge detection, the VM pin voltage rises by the Vf

voltage of the internal parasitic diode than the VSS pin voltage, because the discharge current flows through the

parasitic diode in the charge control FET. If this VM pin voltage is equal to or higher than 0.35 V typ., this IC releases

the overcharge status when the battery voltage is equal to or lower than VCU.

Caution If the battery is charged to a voltage higher than VCU and the battery voltage does not fall below 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 VCU. Since an actual battery has an

internal impedance of tens of m

Ω, the battery voltage drops immediately after a heavy load that

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

detection function.