Document Number: MC33972
Rev. 9.0, 4/2007
Multiple Switch Detection
Interface with Suppressed
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 pullup or pulldown 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.
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 mA or 2.0 mA)
8 Programmable Inputs (Switches to Battery or Ground)
14 Switch-to-Ground Inputs
Typical Standby Current - VPWR = 100 µA and VDD = 20 µA
Active Interrupt (INT) on Change-of-Switch State
Pb-Free Packaging Designated by Suffix Code EW
EW SUFFIX (Pb-FREE)
-40°C to 125°C
Figure 1. 33972 Simplified Application Diagram
* This document contains certain information on a new product.
Specifications and information herein are subject to change without notice.
© Freescale Semiconductor, Inc., 2007. All rights reserved.