S-8254AAAFT-TB-X Datasheet, PDF(14/29 Page) Seiko Instruments Inc

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S-8254AAAFT-TB-X Datasheet, PDF (14/29 Pages) Seiko Instruments Inc – BATTERY PROTECTION IC

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BATTERY PROTECTION IC FOR 3-SERIAL- OR 4-SERIAL-CELL PACK

S-8254A Series

Rev.5.2_00

ï® Operation

Remark Refer to âï® Battery Protection IC Connection Exampleâ.

1. Normal Status

When the voltage of each of the batteries is in the range from VDLn to VCUn and the discharge current is

lower than the specified value (the VINI pin voltage is lower than VIOV1 and VIOV2, and the VMP pin voltage

is higher than VIOV3), the charging and discharging FETs are turned on.

2. Overcharge Status

When the voltage of one of the batteries becomes higher than VCUn and the state continues for tCU or

longer, the COP pin becomes high impedance. The COP pin is pulled up to the EB+ pin voltage by an

external resistor, and the charging FET is turned off to stop charging. This is called the overcharge

status. The overcharge status is released when one of the following two conditions holds.

(1) The voltage of each of the batteries becomes VCLn or lower.

(2) The voltage of each of the batteries is VCUn or lower, and the VMP pin voltage is 39 / 40 Ã VDD or

lower (a load is connected and discharging is started via the body diode of the charging FET).

3. Overdischarge Status

When the voltage of one of the batteries becomes lower than VDLn and the state continues for tDL or

longer, the DOP pin voltage becomes VDD level, and the discharging FET is turned off to stop discharging.

This is called the overdischarge status.

3. 1 Power-down Function

When the overdischarge status is reached, the VMP pin is pulled down to the VSS level by the

internal RVMS resistor of the IC. When the VMP pin voltage is VDD / 2 or lower, the power-down

function starts to operate and almost every circuit in the S-8254A Series stops working. The

conditions of each output pin are as follows.

(1) COP pin : High-Z

(2) DOP pin : VDD

The power-down function is released when the following condition holds.

(1) The VMP pin voltage is VDD / 2 or higher.

The overdischarge status is released when the following two conditions hold.

(1) In case the VMP pin voltage is VDD / 2 or higher and the VMP pin voltage is lower than VDD, the

overdischarge status is released when the voltage of each of the batteries is VDUn or higher.

(2) In case a charger is connected, the overdischarge hysteresis is released. And the

overdischarge status is released when the voltage of each of the batteries is VDLn or higher.

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