Isolated Error Amps Outperform Optocouplers and Shunt Regulators in Power Supply Applications

Analog Devices, Inc. has introduced isolated error amplifiers that 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 5× 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.

ADuM3190/4190 include the following key features: Bandwidth: 400 kHz; 0.5% initial accuracy at 25°C; 1% total accuracy over –40˚C to +125˚C; Low power operation: <7 mA; Isolation voltage, ADuM3190: 2.5 kV rms, ADuM4190: 5 kV rms (reinforced).

These devices are offered in both QSOP-16 (available now) and wide-body SO-16 packages (scheduled to be available in April). Unit prices, in lots of 1,000, range from $1.04 to $1.39.