Isolation between circuit components is often required for security and/or data integrity reasons. For example, isolation protects sensitive circuit components and human-machine interfaces on the system side from dangerous voltage levels present on the field side, where more powerful components such as sensors and actuators are present. Isolation also eliminates common-mode noise or ground loops that affect data acquisition accuracy. While data transfer across the isolation barrier can be achieved with traditional optocouplers or Analog Devices iCoupler devices, the main challenge and common problem is finding a way to transfer power from the non-isolated system side to the isolated field side. This article discusses the technology behind a new approach that addresses this challenge by integrating power isolation and data signal isolation using Analog Devices’ latest iCoupler product.
Until recently, transferring power through an isolation barrier required either a separate DC-DC converter, which was relatively large, expensive, and insufficiently isolated, or a custom discrete approach that was bulky and difficult to design.
These methods are the only viable alternatives, even in applications such as data acquisition modules that require only a small amount of isolated power.
Analog Devices has recently addressed this problem with a complete, fully integrated isolation solution that involves the use of miniature transformers to transmit both signal and power across an isolation barrier. This extension of our iCoupler technology, called isoPower, is a breakthrough alternative. Signal and power within a single component eliminates the need for bulky, expensive, difficult-to-design isolated power supplies and provides adequate isolation up to 5 kV. It can significantly reduce the total cost, board space and design time of an isolation system. As shown in Figure 1, the 2-channel iCoupler device with isoPower is nearly 90% smaller and 70% less expensive.