The NXP MC34978 is a multiple switch detection interface (MSDI) designed to detect the closing and opening of up to 22 switch contacts in industrial environments. * The switch status, either open or closed, is transferred to the microprocessor unit through a serial peripheral interface (SPI) * This SMARTMOS® device also features a 24-to-1 analog multiplexer for reading analog inputs * Individually selectable input currents are available in Normal and Low-Power Mode (LPM), as needed in the application * A battery and temperature monitor are included in the IC and are available via the AMUX pin * This product interfaces with any microcontroller that supports SPI communications