BD3381EKV-C is a 33-channel Multiple Input Switch Monitor IC that detects the opening and closing of mechanical switches. Once it senses a change in the status of a switch, it sends an interrupt signal to the MCU via a serial peripheral interface (SPI). The 33 switch inputs have two types of power supply, VPUB and VPUA. The VPUB and the VPUA power supplies can either be from a battery or from another power supply system. VPUB is the supply for the INB inputs while VPUA is for the INZ and INA inputs. BD3381EKV-C has two modes of operation, Normal and Sleep. In both modes, the internal registers can be set to make the device perform either intermittent or continuous monitoring of the switches. In intermittent monitoring, the switch status is monitored at regular time intervals, allowing the IC to operate with low power consumption. Also, operation with reduced noise can be achieved by enabling uniform sequential monitoring of all switches or sequential monitoring by power supply system.