MC33972抑制唤醒多路开关检测接口

　　The 33972 Multiple Switch Detection Interface with suppressed wake-up is designed to detect the closing and opening of up to 22 switch contacts. The switch status， either open or closed， is transferred to the microprocessor unit （MCU） through a serial peripheral interface （SPI）。 The device also features a 22-to-1 analog multiplexer for reading inputs as analog. The analog input signal is buffered and provided on the AMUX output pin for the MCU to read. The 33972 device has two modes of operation， Normal and Sleep. Normal mode allows programming of the device and supplies switch contacts with pull-up or pull-down current as it monitors switch change of state. The Sleep mode provides low quiescent current， which makes the 33972 ideal for automotive and industrial products requiring low sleep-state currents.