Gallium nitride-based AC/DC converter ICs

Quasi-resonant InnoSwitch3-CP, InnoSwitch3-EP and InnoSwitch3-Pro ICs combine primary, secondary and feedback circuits in a single surface-mounted package. In the newly released family members, GaN switches replace the traditional silicon high-voltage transistors on the primary side of the IC, reducing conduction losses when current is flowing, and considerably reducing switching losses during operation. This results in substantially less wasted energy and therefore increased efficiency and power delivery from the space-saving InSOP-24D package. 

Targeting high-efficiency flyback designs, such as USB-PD and high-current chargers/adapters for mobile devices, set-top boxes, displays, appliances, networking and gaming products, the new AC/DC converter ICs provide accurate CV/CC/CP independent of external components, and easily interface to fast-charging protocol ICs. The InnoSwitch3-CP and EP variants are hardware-configurable, while the InnoSwitch3-Pro incorporates a sophisticated digital interface for software control of CV and CC setpoints, exception handing and safety-mode options.

Balu Balakrishnan, president and CEO of Power Integrations, said: “GaN is a pivotal technology offering significant efficiency and size benefits over silicon. We anticipate a rapid conversion from silicon transistors to GaN in many power applications. InnoSwitch3 has been the clear technology leader in the offline switcher IC market since we launched the silicon variants 18 months ago, and the new GaN-based ICs further extend our lead by advancing both the efficiency and power capability of our flyback products.” 

Power Integrations’ new InnoSwitch 3 ICs are available now, priced at $4/unit in 10,000-piece quantities. Five new reference designs describing USB-PD chargers from 60 to 100W are available on the Power Integrations website, along with an automated design tool, PI Expert, and other technical support documentation.

Commenting at the UK launch, Peter Rogerson, Marcoms Director at Power Integrations, said: “The range of things that can now be powered with this technology has been quite dramatically increased by having this power level and the level of efficiency that comes with it. One of the questions that readily comes up about GaN is that it’s targeted at niche markets, for low volume, specialist products. However, if you look at where we’re targeting these products, they are not small volume, niche marketplaces. It’s GaN to be used in a massive number of sectors.

“GaN transistors are better than silicon transistors, it’s as simple as that. They offer reductions in R_DS(ON), size, footprint and multiple other factors, which mean that it’s just a better technology and one we see as the future. In addition, we enclose and protect the GaN device within our ICs. This means, from the engineers’ point of view, when it comes to designing, it’s not complex, and you don’t have to use complicated topologies (so when we were sampling this with engineers - when you don’t have to disclose your materials - they noticed an incredible increase in performance in something that appeared to be, on the surface at least, exactly the same chip as we had before).

“So, it has simple flyback circuit topology, it uses identical SMPS design flows for the silicon and GaN InnoSwitch2 ICs, has identical switching frequency, external components scale due to power, waveforms are very similar and there are no usual behaviours. So, if you can design with previous generation of InnoSwitches, then you can design with GaN.

“It’s also worth mentioning that it’s the Power Integrations principal that we don’t announce anything unless we’re shipping in volume and the product is manufacturable, as vapourware (i.e. software or hardware that has been advertised but is not yet available), really annoys customers.

“In terms of GaN efficiency we’re talking 95% full-load efficiency, which allows for the elimination of heatsinks from adapter designs. The best silicon can do is around 92%. That may not sound that dramatic, but you’re losing three-eighths of the wasted power. If you did that for any device around the world that is plugged in, then that’s quite a lot of power.

“It’s important to note that circuit operation is indistinguishable from one using silicon devices. We certainly don’t have any worries about capacity. The obvious question that gets asked when you move into a new technology and you’re working with exotic materials is, when it scales, can you cope with it – the answer is a definite yes.

“The manufacturing process is our own, we don’t licence it from anyone else and we don’t plan on licencing it to anyone else. We also are not using GaN on silicon, we’re using GaN on sapphire, and as far as I’m aware we’re the only company doing so (in terms of announcing it as a manufacturing technology).”