High-voltage switcher cuts energy usage in “always-on” smart meters & home automation

September 08, 2014 // By Graham Prophet
This 700-V power management switcher can cut quiescent power consumption by 50%; TI’s 700-V switcher claims the industry’s lowest quiescent current of less than 100 µA – half the power consumption of existing solutions.

The UCC28880 controller integrates a 700-V power MOSFET and high-voltage current source, increasing overall energy efficiency of “always-on” non-isolated power systems with output currents up to 100 mA, such as smart meters, home automation equipment and white goods.

“Hundreds of millions of smart meters around the world continuously draw power from the grid to measure energy use and provide feedback to the utility,” said Dave Freeman, chief technology officer for TI's high-voltage power solutions group. “Even though meters consume relatively small amounts of power that is not charged to the customer, when you multiply the amount of energy needed to power the devices, it makes sense to minimise the energy consumed.”

Designers can use the switcher to build different converter topologies, such as buck, buck-boost and flyback, without adding extra semiconductor components. As the load is reduced, the quiescent current is reduced to below 100-uA. As well as the 700-V MOSFET, there is a start-up current source and internal current sensing in a 7-pin SO package size of 29.4 mm2. No external compensation is needed which further reduces component count and board space. The controller’s inductor current runaway protection helps protect against under load short-circuit conditions to ensure design reliability. The device provides over-temperature protection with hysteretic re-start for safe operation. High-voltage pins are segregated to one side of the package, which maximises separation between low and high voltage pins, or creepage and clearance distances.

An offline, AC/DC reference design based on the UCC28880 (PMP8550) enables designers to create a low-cost, low-power non-isolated high-side buck converter with a total solution size of 38 x 32 x 22 mm that provides up to 13V at up to 100 mA output. The reference design features a buck converter with integrated switch and can be used in numerous industrial applications. The design’s schematic, CAD files and test results are available for download.

The UCC28880 switcher costs $0.55 (1000). The UCC28880 low-side buck evaluation