News and New Products

Chip provides both signal isolation and 500 mW of regulated, isolated power

By Margery Conner, Technical Editor -- EDN, 5/22/2008

The first members of Analog Devices’ isoPower family, ADuM524X, were novel in that they combined signal and power isolation on the same chip. However, the 524X products addressed only those applications needing 10 mW or less power and efficiency of only 10%. The new isoPower family members, the ADuM540x series, overcome those limitations and target mainstream applications, such as sensor interfaces. The devices up the power to 500 mW and the power efficiency to 33%. At first glance, this efficiency may seem low. However, sensors require low current levels, and most discrete dc/dc-converter ICs are less-efficient conversion components at low power levels. The company claims that for a 20-mA current draw, the 540X requires 220 mW—less than half the 490-mW requirement for an optocoupler isolator with a discrete dc/dc converter.

The chips achieve their efficiency by using a larger iCoupler-technology planar transformer, by reducing the rectification losses, and by adding a feedback loop so that the oscillator at the transformer’s input automatically adjusts to the load. The devices can provide as much as 100 mA at either 5 or 3.3V.

The ADuM540x family of $5 (1000), four-channel digital isolators operate at a data rate as high as 25 Mbps and come in 16-lead, wide-body SOIC packages.