MAX31912 Datasheet, PDF (1/18 Pages) Maxim Integrated Products – Ultra-Low Power Industrial

MAX31912
EVALUATION KIT AVAILABLE
Ultra-Low Power Industrial, Octal,
Digital Input Translator/Serializer
General Description
The MAX31912 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 dis-
crete 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. Field-side LED drivers recycle
the current from the eight inputs to provide visual input
status indication without any additional current or power
consumption.
The MAX31912 uses patent-pending circuit techniques
to achieve further reduction of power beyond what is
possible by input current limiting alone.
For low-cost applications, Maxim Integrated offers a pin-
compatible version of this device, the MAX31913, which
does not include the patent-pending current-switching
circuitry included in the MAX31912.
Benefits and Features
●● Ultra-Low Power and Heat Dissipation
• Low Quiescent Current (1.6mA, typ)
• Highly Accurate and Stable Input Current Limiters,
Adjustable from 0.5mA to 6mA
• Special (Patent-Pending) Ultra-Low-Power Mode
with Switched Current Limiters
• Energy-Less Field-Side LED Drivers
●● High Integration Reduces BOM Count, Board Size,
and System Cost
• 8 High-Voltage Input Channels (36V max)
• On-Chip 8-1 Serialization with SPI Interface,
• On-Chip 5V Regulator
• On-Chip Overtemperature Indicator
• Dual On-Chip Field Supply Voltage Monitors
• Integrated Debounce Filters, Selectable from 0 to 3ms
●● Robust Features and Performance for Industrial
Environments
• Multibit CRC Code Generation and Transmission for
Error Detection and More Reliable Data Transmission
• High ESD Immunity on All Field Input Pins
●● Accepts Industry Standard Input Types
• Configurable for IEC 61131-2 Input Types 1, 2, and 3
●● Flexible Power Supply Capability Enables Usage in
5V, 12V, 24V, and Higher Voltage Systems
• Wide Operating Field Supply Range of 7V to 36V
• Can Be Powered from the Logic-Side Using a 5V
Supply
Applications
●● Digital Input Modules for PLCs
●● Industrial, Building, and Process Automation
●● Motor Control
Ordering Information appears at end of data sheet.
19-6925; Rev 3; 4/15