MC34978AES

NXP Semiconductors Document Number: MC33978 Rev. 9, 1/2021 Technical Data 22 channel multiple switch detection 33978 interface with programmable 34978 wetting current MULTIPLE SWITCH DETECTION INTERFACE 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). This SMARTMOS device also features a 24-to-1 analog multiplexer for reading the input channels as analog inputs. The analog selected input signal is buffered and provided on the AMUX output pin for the MCU to read. Independent programmable wetting currents are available as needed for the application. A battery and temperature monitor are included in the IC and ES SUFFIX AE SUFFIX (PB- EK SUFFIX (PB- available via the AMUX pin. (PB-FREE) FREE) FREE) 98ASA00173D The 33978 device has two modes of operation, Normal and Low-power mode 98ASA10556D 98ASA00656D 48-PIN LQFP-EP 32-PIN QFN 32-PIN SOICW- (LPM). Normal mode allows programming of the device and supplies switch (WF-TYPE) EP contacts with pull-up or pull-down current as it monitors the change of state on the switches. The LPM provides low quiescent current, which makes the 33978 ideal for automotive and industrial products requiring low sleep-state currents. Applications Features Automotive Fully functional operation 4.5 V V 36 V BATP Heating ventilation and air conditioning (HVAC) Full parametric operation 6.0 V V 28 V BATP Lighting Operating switch input voltage range from -1.0 V to 36 V Central gateway/in-vehicle networking Eight programmable inputs (switches to battery or ground) Gasoline engine management 14 switch-to-ground inputs Industrial Selectable wetting current (2, 6, 8, 10, 12, 14, 16, or 20 mA) Programmable logic control (PLC) Interfaces directly to an MCU using 3.3 V / 5.0 V SPI protocol Process control, temperature control Selectable wake-up on change of state Input-output control (I/O Control) Typical standby current I = 30 A and I = 10 A BATP DDQ Single board computer Active interrupt (INT B) on change-of-switch state Ethernet switch Integrated battery and temperature sensing Notes 1. The IC is functional from 4.5 V < V < 6.0 V, but with degraded parametric values. The parameters may not meet the minimum and maximum BATP specifications when VBATP drops below 6.0 V. V DDQ Battery Power Supply 33978 SG1 Battery VBATP SP0 Power WAKE B Supply MCU SP1 VDDQ INT B INTB SP7 CS B CSB MISO MISO MOSI MOSI SCLK SCLK SG0 AN0 AMUX SG12 EP SG13 GND Figure 1. 33978 simplified application diagram NXP B.V. 2021.Table of Contents 1 Orderable parts 3 2 Internal block diagram . 4 3 Pin connections 5 3.1 Pinout . 5 3.2 Pin definitions . 6 4 General product characteristics 7 4.1 Maximum ratings . 7 4.2 Thermal characteristics 8 4.3 Operating conditions 9 4.4 Electrical characteristics . 9 5 General description 17 5.1 Features 17 5.2 Functional block diagram . 18 6 General IC functional description 19 6.1 Battery voltage ranges . 19 6.2 Power sequencing conditions 20 7 Functional block description . 21 7.1 State diagram 21 7.2 Low-power mode operation 22 7.3 Input functional block 24 7.4 Oscillator and timer control functional block . 26 7.5 Temperature monitor and control functional block 26 7.6 WAKE B control functional block . 26 7.7 INT B functional block . 27 7.8 AMUX functional block . 27 7.9 Serial peripheral interface (SPI) 28 7.10 SPI control register definition 31 8 Typical applications 53 8.1 Application diagram 53 8.2 Bill of materials . 53 8.3 Abnormal operation 54 9 Packaging . 55 9.1 Package mechanical dimensions . 55 10 Reference section . 65 11 Revision history . 66 33978 NXP Semiconductors 2