Document order number: MC33975
Rev 4.0, 08/2005
Freescale Semiconductor
Technical Data
* 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.
Multiple Switch Detection
Interface with Suppressed
Wake-Up and 32mA Wetting
Current
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.
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.
Features
• Designed to Operate 5.5 V ≤ V
PWR
≤ 28 V
• Switch Input Voltage Range -14 V to V
PWR
• Interfaces Directly to Microprocessor Using 3.3 V/5.0 V SPI
Protocol
• Selectable Wake-Up on Change of State
• Selectable Wetting Current (32 mA or 4.0 mA for switch-to-ground
inputs)
• 8 Programmable Inputs (Switches to Battery or Ground)
• 14 Switch-to-Ground Inputs
•V
PWR
Standby Current 100 µA Typical, V
DD
Standby Current 20 µA Typical
• Pb-free 32-terminal suffix EK
Figure 1. 33975 Simplified Application Diagram
ORDERING INFORMATION
Device
Temperature
Range (T
A
)
Package
MC33975EK/R2
-40°C to 125°C 32 SOICW-EP
PC33975AEK/R2
EK Suffix (Pb-Free)
98ARL10543D
32-TERMINAL SOICW EP
33975
33975A
MULTIPLE SWITCH
DETECTION INTERFACE WITH
SUPPRESSED WAKE-UP
33975
V
BAT
V
BAT
SP0
SP1
SP7
SG0
SG1
SG12
SG13
VPWR
VDD
AMUX
WAKE
GND
INT
SO
SI
SCLK
CS
MCU
AN0
INT
MISO
MOSI
SCLK
CS
Power Supply
LVI
Watchdog
Reset
Enable
V
BAT
V
DD
V
DD