MAXREFDES27#: Optical Proximity Sensor, IO-Link

The MAXREFDES27# is a tiny IO-Link proximity sensor with an IR receiver, matching IR LED driver, IO-Link transceiver, and energy-efficient step-down converter all on an 8.2mm x 31.5mm printed circuit (PC) board. Maxim Integrated and Technologie Management Gruppe Technologie und Engineering (TMG TE) collaborated in designing the MAXREFDES27# as an IO-Link version 1.1/1.0 compliant proximity sensor reference design. The MAXREFDES27# design consists of an industry standard Maxim Integrated IO-Link device transceiver (MAX14821), a tiny low-dropout linear regulator (MAX8532), an efficient high-voltage step-down converter (MAX17552), a Renesas ultra-low-power 16-bit microcontroller (RL78) utilizing TMG TE's IO-Link device stack, and a Maxim Integrated proximity sensor (MAX44000).

Today's factories rely more on automation and less on manual labor. With this increased use of robotics comes the increased need for proximity sensing. Proximity sensors are devices that can sense when an object is a specific distance away from a reference point location. They are able to act as a switch by flipping when the target object passes a predefined distance threshold. They can also provide continuous readings when objects are changing distances within a sensor's range. Several types of proximity sensors exist today such as optical, inductive, capacitive, ultrasonic, magnetic, and even mechanical. Some applications have special requirements that may make one type better suited than another. Optical sensors are extremely versatile, due to the rapid development of photoelectric technology. This versatility allows them to solve the bulk of the industrial proximity sensing needs1. Such needs include sensing of metallic or non-metallic objects, very small objects, over long distances, and with fast response times.

Factories are also moving towards using universally accepted industrial protocols. IO-Link is the first open, field bus agnostic, low-cost, point-to-point serial communication protocol used for communicating with sensors and actuators that has been adopted as an international standard (IEC 61131-9)2. IO-Link finally standardizes interoperability of industrial equipment from all over the world. IO-Link can function directly from the PLC or can be integrated into all standard field buses, quickly making it the defacto standard for universally communicating with smart devices like the MAXREFDES27#. IO-Link, being simple yet intelligent, allows for the smallest low-cost smart sensors in the industry.