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The 33972 Multiple Switch Detection Interface with suppressed

wake-up 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 analog input signal is buffered and provided on

the AMUX output pin for the MCU to read.

The 33972 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 switch change

of state. The Sleep mode provides low quiescent current, which makes

the 33972 ideal for automotive and industrial products requiring low

sleep-state currents.

Features

? Designed to operate 5.5 V ? VPWR ? 26 V

? Switch input voltage range -14 V to VPWR, 40 V Max

? Interfaces directly to MPU using 3.3 V/5.0 V SPI protocol

? Selectable wake-up on change of state

? Selectable wetting current (16 or 2.0 mA)

? 8 programmable inputs (switches to battery or ground)

? 14 switch-to-ground inputs

? Typical standby current - VPWR = 100 ?A and VDD = 20 ?A

? Active interrupt (INT) on change-of-switch state