Circuitry creates clean, cheap conversion

This article originally appeared in the Oct'22 magazine issue of Electronic Specifier Design – see ES's Magazine Archives for more featured publications.

Proprietary circuitry which regulates the flow of mains power to the charging capacitor is at the heart of Pulsiv’s Osmium microcontroller series. PFC (power factor correction) can be achieved without the need for a switched inductor. Instead a small storage capacitor is charged with one switch and discharged using a second diode switch.

The switching architecture and intelligent control combine to deliver consistent performance across the full load range while meeting strict efficiency requirements at low power, says the company.

The company, a spinout from the University of Plymouth, was founded in 2013 by Dr Zaki Ahmed, associate professor in IT at the University of Plymouth. He developed the switching technology to regulate the flow of mains to the charging capacitor eliminating inrush current completely. 

This proprietary circuit technology is used in the Osmium microcontroller. It reduces the energy consumed by AC/DC power supplies and battery chargers under all operating conditions, says the company.

The 150W PSV-AD-150 and 250W PSV-AD-250 microcontrollers, together with supporting components can be combined with commodity flyback DC/DC converters in place of more expensive LLCs. The Pulsiv technology can be used in place of NTC thermistors or fixed resistors with bypass, both of which have limitations, or in place of trailing edge phase dimming or pulse charging input capacitors, both of which add design complexity.

The switching technology can reduce costs because the majority (95%) of the bill of materials is commodity products, such as capacitors, resistors, diodes and low voltage transistors. In the basic configuration, just six critical components, such as ICs, magnetics, high voltage switches and storage capacitor are required, rising to seven with hold up and 11 if an active bridge is required.

The critical components operate at lower temperatures, even under convection cooling, to extend operating life. In addition to active bridge control, Osmium technology also supports optional features, e.g., configurable hold up, x-cap discharge, high voltage DC output selection, a power consumption indicator and grid failure detection.

Efficiency is up to 99.5% and the performance is consistent, even at low power, although this efficiency can be further improved through the use of premium components, adds Pulsiv’s CEO, Darrel Kingham.

“We want efficient power supplies to be the norm and to get efficient power supplies at less cost and minimise the amount wasted,” he told Electronic Specifier.

The company has demonstrated a universal input, single switch 150W flyback power supply design that delivers 97.5% average (99.5% peak) front-end efficiency while maintaining 90% at just 2.0W.

Looking ahead, a 240W interleaved flyback is being developed. Full power reference designs include the PSV-AD-250-DS development system which can be configured for specific design requirements. It can interface with any compatible DC/ DC converter to produce a compact power supply prototype up to, and beyond, 250W. 

The PSV-AD-150 and PSV-AD-250 microcontrollers are sampling now and are available through distribution partners, including Digi-Key and additionally Astute in Europe.