The process of developing analog input modules for PLC or DCS applications, historically, used to come with significant tradeoffs in performance vs. cost. The new generation of analog-to-digital converters, such as the AD4111 from Analog Devices, have higher performance and better efficiency than their predecessors. In this article, learn more about the underlying technologies that enable these newest products.
There are four main improvements to modern ADCs: An integrated front end, open-wire detection, better system integration, and more robust EMC testing.
Integrated Front End
Featuring adaptable, integrated designs, modern ADCs such as the 24-bit Σ-Δ AD4111 eliminate the need for external components. This simplifies the product design process and lowers costs as well. For example, the AD4111 can accept ±10V voltage inputs, 0 mA to 20 mA current inputs, and can operate off of a single 5V or 3.3V power supply. In the past, this level of adaptability would have required additional buffers and other components, driving up cost and complexity. However, all of that functionality is integrated onto one device now.
Open Wire Detection
Older, single 5V designs have usually lacked native open wire detection functionality. It could be added after the fact, though, at additional expense. The AD4111 has open wire detection built-in, making it simpler to integrate this component into your design.
System-Level Solution
With an integrated voltage reference and internal clock, the AD4111 can help to reduce board size and complexity as compared to existing modular designs.
EMC Testing
PLC and DCS modules often operate in tough industrial environments which may include high levels of electromagnetic interference. With proven EMC performance, low susceptibility to RF interference, sufficient immunity to electrostatic discharge, and CISPR11 compliance, the AD4111 is robust enough to perform in the most demanding applications.
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