MC33978 Datasheet | NXP Semiconductors

22-channel multiple switch detection interface with programmable wetting current Rev. 10 - 20 August 2024 Product data sheet 1 General description The 33978 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). Individually selectable input currents are available in Normal and Low-power (LPM) modes, as needed for the application. It also Features a 24-to-1 analog multiplexer for reading inputs as analog. The analog input signal is buffered and provided on the AMUX output pin for the MCU to read. A battery and temperature monitor are included in the IC and available via the AMUX pin. The 33978 device has several modes of operation: Normal mode, Low-power mode (LPM), and Polling mode. Normal mode allows programming of the device and supplies switch contacts with pull-up or pull-down current as it monitors the change of state of switches. The LPM provides low quiescent current, which makes the 33978 ideal for automotive and industrial products requiring low sleep-state currents. Polling mode periodically interrogates the input pins to determine the state the pins are in, and to decide whether there was a change of state from Normal mode. Note: The IC is functional from 4.5 V < VBATP < 6.0 V, but with degraded parametric values. The parameters may not meet the minimum and maximum specifications when VBATP drops below 6.0 V. NXP Semiconductors 22-channel multiple switch detection interface with programmable wetting current Battery Battery SP0 SP1 SP7 SG0 SG12 VDDQ VBATP SG1 Power supply WAKE_B VDDQ Power supply INT_B CS_B MISO MOSI SCLK AMUX INTB CSB MISO MOSI SCLK AN0 SG13 EP GND Figure 1. Simplified application diagram MCU aaa-055953 Product data sheet All information provided in this document is subject to legal disclaimers. Rev....