Power trip: new integrated device sends power and data over isolation barrier

Adjusting the thermostat to beat the summer heat brings to life many high-voltage circuits, including those that drive the air-conditioner’s compressor and blower motors that cool the house and make life more comfortable.

The space available for these drive and control circuits is small, subject to a lot of noise and vibration, and exposed to more pollution than indoor applications. In that limited space, designers must devise a way to get both power and data for control signaling safely over an isolation barrier to the high-voltage motors, while protecting the person at the thermostat.

“Isolation barriers are essential to allow people to safely interact with what is increasingly becoming a world full of efficient high-voltage drives and actuators driven by explosive growth in industrial and home automation,” said Kannan Soundarapandian, our Isolation Products product line manager. “Isolators allow high voltage circuits to talk to low voltage circuits – essentially machine talking to machine − without killing each other.”

The need for isolated data and power in motor drives and factory and building automation applications has been growing steadily, and the story is similar in areas such as electric grid, medical, and test and measurement applications. Our isolation technology is a perfect fit for reliability and performance in those applications.

Our company released the industry-leading ISO7840 reinforced digital isolator family in 2014. But integrating an isolated DC/DC converter to transfer power into this technology proved elusive.

Until now.

A new integrated device sends both data and power over the isolation barrier in a single, robust package that’s a fraction of the size required to discretely accomplish the same task previously.

ISOW7841 runs much cooler, with 80 percent greater efficiency, and much quieter, with more than 10dB reduction in radiated noise levels than competitive solutions today.

“Given its sheer ease of use and the accelerated time to market it gives developers, we call it the Swiss army knife of isolation products,” Kannan said.

Another key benefit − particularly over discrete implementations of isolated power − is that the ISOW7841 helps with easier and faster system certification.

Worldwide certifications

For many applications, sending power over an isolation barrier required installing a discrete – and bulky – transformer on a circuit board. This approach creates reliability problems, consumes valuable board space, and puts the burden of complying with complex and time-consuming safety certifications squarely on the system designer.

The new innovation combines isolated data and power in a single, much-smaller package.

“The idea was to get board space back, achieve the highest levels of reliability and lifetime operation with unprecedented efficiency and emission performance across a wide temperature range, and put it all in the strongest technology available,” Kannan said. “We succeeded. That’s exciting.”