Reduce power, size and cost of PLC digital-input subsystems

27th August 2013

Nat Bowers

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Designers can now reduce power, size and system cost for programmable logic controller digital-input subsystems, with the Corona (MAXREFDES12#) reference design from Maxim. 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 the MAX13256 transformer driver, the Corona design reduces isolated channels and eliminates the need for power-hungry optocouplers and discrete parts.

This design reduces isolated channels and leverages analog integration for industrial control and automation applications. 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.

Tony Partow, Senior Business Manager at Maxim, comments: “The MAX31911 incorporated in Corona uses up to 80% less supply current compared to the competition. 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.”

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.

Availability and pricing: