Analog Mixed Signal and Power Management MC33972 Multiple Switch Detection Interface with Suppressed Wake-up Applications MC33972 Simplified Application Diagram • Automotive Systems VDD • Aircraft Systems • Industrial Control Systems • Process Control Systems VBAT 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 terminal 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. LVI VPWR VDD ENABLE VDD SP7 WAKE SG0 SG1 Overview POWER SUPPLY 33972 SP0 SP1 • Security Systems • Critical systems requiring switch status verification for safety, operation, or process control purposes VBAT VBAT SG12 SG13 MCU MOSI SCLK CS MISO INT AN0 SI SCLK CS SO INT AMUX GND Performance Typical Values Operating Voltage 5.5 V ≤ VPWR ≤ 26 V Switch Voltage Range -14 to VPWR Contact Wetting Current 2.0 or 16 mA Quiescent Current: VPWR VDD < 100 µA < 20 µA Control SPI Outputs 4 WATCHDOG RESET Analog Mixed signal and Power Management Features Customer Benefits Questions • Switch input voltage range -14 V to VPWR, 40 V Max • Optimized multiple switch OPEN/ CLOSE status verification with immediate reporting to the MCU • Do you need to confirm the status of multiple switches in your system? • Interfaces directly to microprocessor using 3.3 V/5.0 V SPI protocol • • • • • • Interfaces to 3.3 V/5.0 V MCUs with SPI Selectable wake-up on change of state • Surface-mounted device, requires Selectable wetting current (16 mA or minimal PC board space, few 2.0 mA) components, enhanced application 8 programmable inputs (switches to reliability, and lower costs battery or ground) • Simple power conservation solution 14 switch-to-ground inputs providing a WAKE output for system wake-up from Sleep mode VPWR standby current 100 μA typical, VDD standby current 20 μA typical • Active interrupt (INT) on change-ofswitch state • Pb-free packaging designated by suffix code EW and EK • Devices available for comparison are in the Analog Product Selector Guide SG1002 and Automotive Product Selector Guide - SG187 Temperature Range Package MC33972TEW/R2 -40 to 125°C 32 SOICW MC33972ATEW/R2 -40 to 125°C 32 SOICW MC33972ATEK/R2 -40 to 125°C 32 SOICW-EP • Do you need a switch verification device that is also capable of controlling small LEDs as well as MOSFET transistors? • Do you need a switch verification device programmed and controlled via SPI? • Do you need a switch monitoring device that “sleeps” until switches change status and then alerts the MCU that a switch state has changed? 0.65 mm Pitch 7.5 x 11.0 mm Body Evaluation Board KIT33972AEWEVBE • Do you need a switch verification device capable of analog voltage multiplex readout of sensing inputs? 32 SOICW/EP Ordering Information Device • Do you need to verify a switch is closed to battery or ground? Evaluation Board Documentation MC33972 Data sheet order number SG1002 Analog Product Selector Guide SG 187 Automotive Product Selector Guide Learn More: For current information about Freescale products, please visit www.freescale.com. Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc., 2011. All rights reserved. Document Number: MC33972FS REV 6.0