The NXP® MC33978AEK is a multiple switch detection interface (MSDI) 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 through a SPI in automotive environments.
This SMARTMOS® device features a 24-to-1 analog multiplexer for reading analog inputs
The analog input signal is buffered and provided on the analog multiplexer (AMUX) output pin for the MCU to read
Individually selectable input currents are available in Normal and Low-Power Mode
Battery and temperature monitor are included in the IC and available via the AMUX pin
Interfaces with any MCU that supports SPI communications
Feature
Designed to operate 4.5 V ≤ VBATP ≤ 36 V
Switch input voltage range -14 V to VPWR, 36 V Max.
Interfaces directly to an MCU using 3.3 V / 5.0 V SPI protocol
Selectable wake-up on change of state
Selectable wetting current (2, 6, 8, 10, 12, 14, 16, or 20 mA)
8 programmable inputs (switches to battery or ground) and 14 switch-to-ground inputs
Typical standby current - VBATP = 30 uA and VDD = 10 uA
Integrated battery and temperature sensing
Catalogue
FPGA / CPLD
Memory
MOS 
MCU 
DSP
OCEP
Secondary 
Other 
