S-8235AAA-TCT1U Datasheet, PDF (13/24 Pages) Seiko Instruments Inc – FOR AUTOMOTIVE BATTERY PROTECTION IC

FOR AUTOMOTIVE BATTERY PROTECTION IC FOR 3-SERIAL TO 5-SERIAL CELL PACK (SECONDARY PROTECTION)
Rev.1.7_00
S-8235A Series
 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,
and then the S-8235A Series spuriously becomes overcharge status (Refer to Figure 8). I_VCLn or I_VCHn flows in R_VCn during
the self-test operation. Since the S-8235A Series detects overcharge when the voltage between voltage monitoring pins
exceeds overcharge detection voltage n (V_CUn), it is possible to confirm whether the S-8235A Series normally detects the
overcharge or not by monitoring the CO pin output signal.
RVC1 VC1
V1 (< V_CU1)
R_{VC2 VC2}
+
CO
"H"
−
I_VCL2
V2
V1 + I_VCL2 × R_VC2 (≥ V_CU1)
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 kΩ, 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.
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