Simplify Isolated Digital Inputs to an Industrial PLC While Reducing Power, System Cost, and Size

Designers now have a way to reduce power, system cost, and size for programmable logic controller (PLC) digital-input subsystems, with the Corona (MAXREFDES12#) reference design by Maxim Integrated Products, Inc. (NASDAQ: MXIM). This design reduces isolated channels and leverages analog integration for industrial control and automation applications.

One method of reducing the size of I/O solutions in PLCs is to reduce the number of digital channels that need to be isolated. Integrating three Maxim products including a transformer driver, the Corona design reduces isolated channels and eliminates the need for power-hungry optocouplers and discrete parts. These savings reduce power by 16%, solution size by 38%, and cost by 23%. Maxim's devices used in Corona are designed specifically for harsh industrial environments with operating temperature ranges from -40°C to +125°C, so they are ideal for use in PLCs and other automation applications.

Key Advantages

• Analog integration: reduces isolation channels to four while Maxim's digital isolator eliminates the need for optoisolators; optimized for 16, 24, and 32 input channel designs, the digital input serializer's SPI busses can be daisy-chained to further reduce isolation channel count, leading to increased savings
• Lower power: best-in-class power consumption; uses 16% less power than the traditional design approach
• Lower cost: uses 38 fewer parts than a traditional design to create a less expensive integrated solution
• Smaller size: provides 51% fewer components than a traditional design.

Corona's Integrated Products

• MAX31911: industrial, octal, digital input translator/serializer delivers best-in-class power consumption and reduces component count on the board
• MAX14850: 6-channel digital isolator enables low power consumption and stable high-temperature performance; UL1577, CSA, IEC 60747-5-2 safety certified. Replaces optoisolators, which have limited LED lifespan, with a 5x longer life solution
• MAX13256: 36V H-bridge transformer driver simplifies isolated power designs

Industry Commentary

• “The MAX31911 incorporated in Corona uses up to 80% less supply current compared to the competition,” said Tony Partow, Senior Business Manager at Maxim Integrated. “This demonstrates our expertise in analog integration, coupled with our state-of-the-art high-voltage semiconductor process technologies. Corona is one example of how our reference designs accelerate the design process, while also providing innovative solutions.”
• “Reference designs are increasingly important as designers seek to develop sophisticated solutions and reduce development cycle times,” said Susie Inouye, Research Director and Founder of Databeans.

Availability and Pricing

• Complete reference design available in a 90mm x 20mm Pmod™ form factor.
• Pricing for Corona starts at $45 (FOB USA).
• Available through distribution channels today.