A daisy-chain SPI interface in a battery voltage monitoring IC for electric vehicles

This paper presents a current-mode Serial Peripheral Interface (SPI) in a battery voltage monitoring (BVM) IC for electric vehicles (EVs). In the BVM system, multiple cascaded BVM ICs are required to communicate with the MCU, which places big challenges to the design of the bus interface circuits. A current-mode SPI interface of the BVM IC is presented in this paper to form a daisy-chain bus configuration between the cascaded BVM ICs and the MCU, which can avoid the issues of isolated communication, and reduce the required I/O ports of the MCU extensively. The BVM IC is fabricated in a 0.5?m BCD process. Measurement results show that the presented SPI interface achieves a date rate up to 1Mbps, while consumes 3mA in the operation mode.