Analog, Mixed Signal and Power Management Fact Sheet MC33975 Multiple Switch Detection Interface with Suppressed Wake-up and 32 mA Wetting Current Applications MC33975 Simplified Application Diagram • Automotive systems VDD • Industrial control systems • Process control systems • Security systems • Systems requiring switch status verification for safety, operation, or process control purposes Overview Freescale offers Multiple Switch Detection Interface Devices. The MC33975 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 MC33975 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 MC33975 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 and 4.0 mA for switchto-ground inputs, and an interrupt bit that can be reset. VBAT 33975 SP0 SP1 VBAT POWER SUPPLY LVI VBAT VPWR VDD ENABLE VDD SP7 WAKE SG0 SG1 SG12 SG13 SI SCLK CS SO INT AMUX MCU MOSI SCLK CS MISO INT AN0 WATCHDOG RESET GND Performance Inputs Switch Voltage Range 33975 33975A Operating Voltage Contact Wetting Current Quiescent Current: VPWR VDD Control Operating Temperature Typical Values 8 programmable, 14 switch-to-ground -14 V to VPWR, 38 V max -14 V to VPWR, 40 V max 5.5 – 28 V (VPWR) 4.0 or 32 mA < 70 A < 10 A SPI -40 °C TA 125 °C Analog Mixed signal and Power Management Features Customer Benefits Questions • Designed to operate 5.5 V VPWR 28 V • Optimized switch OPEN/CLOSE status verification of multiple switches with changes immediately reported to the MCU • Do you need to confirm the status of multiple switches in your system? • Programmable levels of verification performance • Do you need a switch verification device capable of analog voltage multiplex readout of sensing inputs? • Switch input voltage range -14 V to VPWR, 40 V max • Interfaces directly to microprocessor using 3.3/5.0 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 • VPWR standby current 100 A typical, VDD standby current 20 A typical • Pb-free 32-terminal suffix EK • Additional devices available for comparison in the Analog Product Selector Guide, SG1002 and Automotive Product Selector Guide, SG187 • Simple interfacing to industry-standard 3.3/5.0 V MCUs having SPI • Surface mounted device requiring minimal PC board space and few components, enhancing application reliability and lower costs • Simple system power conservation solution providing a WAKE output with which the MCU power supply can be enabled when MCU activation is required • Increased wetting current • Increased operating voltage • Multiple 33975 devices in a module system Temperature Range Package MC33975TEK/R2 -40 to 125 °C 32 SOICW-EP MC33975ATEK/R2 -40 to 125 °C 32 SOICW-EP Evaluation Board KIT33975AEWEVBE • Do you need a switch verification device that is also capable of controlling small LEDs as well as FET transistors? • Do you need a switch verification device programmed and controlled via the SPI? • Do you need a switch monitoring device that “sleeps” so long as switches do not change status and alerts the MCU when a switch state changes? 32 SOICW - EP Ordering Information Device • Do you need to verify a switch is connected to VBAT or Ground? Evaluation board 98ASA10556D 0.65 mm Pitch 7.5 x 11.0 mm Body Documentation MC33975 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: MC33975FS REV. 7.0