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NXP Semiconductors Technical Data
22 channel multiple switch detection interface with programmable wetting current
Document Number: MC33978 Rev. 8.0, 7/2018
33978 34978
The 33978 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). This SMARTMOS device also features a 24-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.
Independent programmable wetting currents are available as needed for the application. A battery and temperature monitor are included in the IC and available via the AMUX pin.
33978 Datasheet
