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 pullup 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. Freescale offers multiple Switch Dectection Interface Devices. The 33975 device offers the following improvements: (a) the programmable interrupt timer for Sleep mode can be disabled, (b) switch detection currents are 32 mA and 4.0 mA for switch-to-ground inputs, (c) the interrupt bit is a reset bit, and (d) the package is a Pb-free 32-lead exposed pad.Designed to Operate 5.5 V= VPWR= 28 VSwitch Input Voltage Range -14 V to VPWR, 40 V MaxInterfaces Directly to Microprocessor Using 3.3 V/5.0 V SPI ProtocolSelectable Wake-Up on Change of StateSelectable 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 InputsVPWR Standby Current 100µA Typical, VDD Standby Current 20µA TypicalPb-Free Packaging Designated by Suffix Code EK