MC33CD1020AESR2 is a cost optimized multiple switch detection interface device 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 through a Serial Peripheral Interface. This SMARTMOS device also features a 22-to-1 analog multiplexer for reading the input channels as analog inputs. The analog selected input signal is buffered and provided on the AMUX output pin for the MCU to read. It has two modes of operation, normal and low-power mode. Normal mode allows programming of the device and supplies switch contacts with pull-up or pull-down current as it monitors the change of state on the switches. It provides low quiescent current, which makes CD1020 ideal for automotive and industrial products requiring low sleep-state currents. Application includes automotive, heating ventilation and air conditioning, lighting, central gateway/in-vehicle networking, gasoline engine management.