MC33975抑制唤醒和32毫安润湿电流的多开关检测接口

　　The 33975 Multiple Switch Detection Interface with Suppressed Wakeup 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 33975 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 the switch change of state. The Sleep mode provides low quiescent current， which makes the 33975 ideal for automotive and industrial products requiring low sleep state currents. Improvements are a programmable interrupt timer for Sleep mode that can be disabled， switch detection currents of 32 mA and 4.0 mA for switch-to-ground inputs， and an interrupt bit that can be reset. This device is powered using SMARTMOS technology.