FOR AUTOMOTIVE BATTERY PROTECTION IC FOR 3-SERIAL TO 5-SERIAL CELL PACK (SECONDARY PROTECTION)

S-8235A Series

Seiko Instruments Inc.

13



Self-test Function

The S-8235A Series has a self-test function to confirm overcharge detection operation.

Due to the self-test function, a current flows in an external resistor, the voltage between voltage monitoring pins expands,

the self-test operation. Since the S-8235A Series detects overcharge when the voltage between voltage monitoring pins

overcharge or not by monitoring the CO pin output signal.

VC1

VC2

+

−

CO

V1 (

V1

"H"

V2

Figure 8 Self-test Operation between VC1 Pin and VC2 Pin

When not using the self-test function, short-circuit the CLKI pin and the VDD pin, the RSTI pin and the VDD pin via a

resistor of 1 k

Ω, respectively. And short-circuit the CAI pin and the NPI pin via a resistor of 1 kΩ.

1. Self-test operation at the time of cascade connection

The S-8235A Series devices can be connected in cascade.

By connecting as shown in Figure 7, the S-8235A Series protects 6-serial or more cells lithium-ion rechargeable battery

pack.

At the time of cascade connection, the CO pin output signal for upper device of the S-8235A Series is transmitted by

connecting the CO pin and the CTL pin, and is output from the CO pin at the lower device. Therefore, it is possible to

confirm whether all devices of the S-8235A Series normally detects the overcharge or not by monitoring the CO pin

output signal for the lowest device of the S-8235A Series.

On the other hand, the CAO pin output signal for the upper device of the S-8235A Series is transmitted by connecting

the CAO pin and the CAI pin, and is output from the CAO pin at the lower device. Therefore, it is possible to confirm

which device of the S-8235A Series is in a self-test operation by monitoring the CAO pin output signal for the lowest

device of the S-8235A Series.