Industrial, Octal, Digital Input Translator/Serializer

Industry's Most Robust Low-Power Industrial Digital Input Serializer


The MAX31911 industrial interface serializer translates, conditions, and serializes the 24V digital output of sensors and switches used in industrial, process, and building automation to 5V CMOS-compatible signals required by microcontrollers. It provides the front-end interface circuit of a programmable logic controller (PLC) digital input module. The device features integrated current limiting, lowpass filtering, and channel serialization. Input current limiting allows a significant reduction in power consumed from the field voltage supply as compared to traditional discrete resistor-divider implementations. Selectable on-chip lowpass filters allow flexible debouncing and filtering of sensor outputs based on the application. On-chip serialization allows a drastic reduction in the number of optocouplers used for isolation. The device serializer is stackable so that any number of input channels can be serialized and output through only one SPI-compatible port. This reduces the number of optocouplers needed to only three, regardless of the number of input channels. For enhanced robustness with respect to high-frequency noise and fast electrical transients, a multibit CRC code is generated and transmitted through the SPI port for each 8 bits of data. The on-chip 5V voltage regulator can be used to power external optocouplers, digital isolators, or other external 5V circuitry.

For ultra-low-power applications, Maxim offers a pin-compatible version of this device, the MAX31910. The MAX31910 uses patent-pending circuit techniques to achieve further reduction of power beyond what is possible by input current limiting alone.

The future generation version of the MAX31910 and MAX31911 will include energy-less LED drivers while maintaining pin compatibility.
MAX31911: Block Diagram MAX31911: Block Diagram Enlarge+

Key Features

  • Eight High-Voltage Input Channels (36V max)
  • Configurable for IEC 61131-2 Input Types 1, 2, 3
  • Wide Operating Supply Range of 7V to 36V
  • Optional Configuration Allows 5V Supply
  • Selectable Input Filtering and Debouncing from 0ms to 3ms
  • Configurable Input Current Limiting from 0.5mA to 6mA
  • High HBM ESD Immunity on All Field Input Pins
  • On-Chip 8-to-1 Serialization with SPI Interface
  • On-Chip 5V Regulator
  • Overtemperature Indicator
  • On-Chip 24V Field Supply Voltage Monitor
  • Low Quiescent Current and Power Dissipation
  • Multibit CRC Code Generation and Transmission for Error Detection and More Reliable Data Transmission to an External Micro


  • Building Automation
  • Digital Input Modules for PLCs
  • Industrial Automation
  • Motor Control
  • Process Automation
Part Number Sensor Interface Type µC Interface Type Channels VSUPPLY
Low Pwr. Shutdn Oper. Temp.
min max typ See Notes
MAX31911  IEC 61131-2 Digital Input Types 1, 2, 3 SPI 8 10 36 1400 No -40 to +125 $1.71 @1k
See All Sensor Interface Devices (10)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX31910EVKIT: Evaluation Kit for the MAX31910 and MAX31911
MAX31911EVKIT: Evaluation Kit for the MAX31910 and MAX31911

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