Device combines signal and power isolation
By Margery Conner, Technical Editor -- EDN, March 21, 2006
Building on its iCoupler technology, which includes chip-scale microtransformers directly in the chip substrate, Analog Devices is offering what it claims is the first device to combine signal and power isolation in the same chip. The ADuM524X isoPower family of dual-channel isolators integrates isolated power supplies and regulators that provide as much as 50 mW of isolated, regulated power at 5V with two isolated digital-signal channels. The devices target low-power isolation, such as factory-automation equipment, instrumentation, and secondary-control power supplies.
One popular method of signal isolation uses optocouplers, which combine LEDs and pho-tosensitive transistors, but these devices have limitations: Their characteristics can vary with age and temperature. In addition, although optoisolators can isolate signals, they can’t isolate power. The isoPower technology, which Analog Devices based on planar transformers, can do both signal and power isolation in one package for a significant cost and space savings and still provide isolation ratings as high as 5 kV. The ADuM524X family members vary by the directionality of each channel. The ADuM5240, targeting data-acquisition applications, has two signal outputs on the same side as the power output.
The ADuM5241 has signal channels in each direction, and it targets bidi-rectional communications, such as RS-232 transceivers, that require isolated power for interface electronics. The ADuM5242, with the two signal outputs on the same side as the power input targets power-supply applications that employ secondary-side control and require isolated power to initiate start-up. The devices come in eight-lead, narrow-body, lead-free SOIC packages and cost $2.95 (1000).
