Document Number: MC34972
Rev. 1.0, 9/2013
Multiple Switch Detection
Interface with Suppressed
The 34972 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 34972 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 34972 ideal for industrial products requiring low sleep-state
currents. This device is powered by SMARTMOS technology.
• 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)
• Eight programmable inputs (switches to supply 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
EW SUFFIX (Pb-FREE)
EK SUFFIX (Pb-FREE)
32-PIN SOICW EP
-40 to 85 °C
32 SOICW EP
Figure 1. 34972 Simplified Application Diagram
Freescale Semiconductor, Inc. reserves the right to change the detail specifications,
as may be required, to permit improvements in the design of its products.
© Freescale Semiconductor, Inc., 2013. All rights reserved.