NXP MC34978AEK

MC34978AEK is a 22 channel multiple switch detection interface with programmable wetting current. It is designed to detect the closing and opening of upto 22 switch contacts. The switch status, either open or closed, is transferred to the microprocessor unit (MCU) through a serial peripheral interface (SPI). This SMARTMOS device also features a 24-to-1 analogue multiplexer for reading the input channels as analogue inputs. The analogue selected input signal is buffered and provided on the AMUX output pin for the MCU to read. Independent programmable wetting currents are available as needed for the application. This device has two modes of operation, normal and low-power mode (LPM). 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. The LPM provides low quiescent current, which makes the 33978 ideal for automotive and industrial products requiring low sleep-state currents.