Isolated Error Amplifiers Outperform Optocouplers

Isolated error amplifiers from Analog Devices Inc. provide power supply designers with a higher performing, single-chip alternative to isolation techniques based on optocouplers and shunt regulators. Designed for linear feedback power supplies using primary side controllers, the ADuM3190 and ADuM4190 isolated error amplifiers have a 400-kHz bandwidth, with 0.5% typical initial accuracy at 25°C and 1% total accuracy over the extended temperature range of -40°C to +125°C. This provides manufacturers of ac-to-dc and dc-to-dc power supplies, including those that are DOSA (Distributed-power Open Standards Alliance)-compliant, with a significant upgrade in speed and operating temperature range, as well as a 5x improvement in transient response.

Designed with ADI's iCoupler®  digital isolation technology, the ADuM3190 and ADuM4190 eliminate the CTR (current-transfer ratio) of optocouplers that degrades over the lifetime of the devices and limits operation to 85°C. The ADuM3190 and ADuM4190 include a highly accurate 1.225-V reference and a wideband operational amplifier that can be used to set up a variety of commonly used power supply loop compensation techniques.