Document order number: MC33975
Rev 4.0, 08/2005
Multiple Switch Detection
Interface with Suppressed
Wake-Up and 32mA Wetting
Freescale offers multiple Switch Detection Interface Devices. The
33975 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.
DETECTION INTERFACE WITH
The 33975 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 33975 ideal for automotive and industrial products requiring low
sleep state currents.
Improvements are a programmable interrupt timer for Sleep mode
that can be disabled, switch detection currents of 32 mA and 4.0 mA
for switch-to-ground inputs, and an interrupt bit that can be reset.
EK Suffix (Pb-Free)
32-TERMINAL SOICW EP
• Designed to Operate 5.5 V ≤ VPWR ≤ 28 V
• Switch Input Voltage Range -14 V to VPWR
• Interfaces Directly to Microprocessor Using 3.3 V/5.0 V SPI
• Selectable Wake-Up on Change of State
-40°C to 125°C
• Selectable Wetting Current (32 mA or 4.0 mA for switch-to-ground
• 8 Programmable Inputs (Switches to Battery or Ground)
• 14 Switch-to-Ground Inputs
• VPWR Standby Current 100 µA Typical, VDD Standby Current 20 µA Typical
• Pb-free 32-terminal suffix EK
Figure 1. 33975 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., 2005. All rights reserved.