Eggtronic launches power controller based on RISC-V architecture

Igor Spinella and Nick Flaherty founded the chip company Eggtronic to develop RISC-V-based power controllers and have now raised 15 million euros.

Italian chip maker Eggtronic plans to launch a series of highly integrated AC-DC conversion control chips, and recently successfully launched the first controller based on the RISC-V core.

“QuarEgg technology was born to solve the problems of quasi-resonant and active clamping technologies,” said Igor Spinella, CEO and founder of Modena-based Eggtronic. Using zero voltage switching (ZVS) technology across the load, it can support high-efficiency chargers up to 45W.

“In the first quarter of next year we will launch SmartEgg, which is a single-stage power factor correction (PFC) and power converter. Then the next one will be ClassEgg, which is a fully resonant architecture that allows for higher power and the load can be always 50% above the nominal voltage.”

“RISC-V is not built from scratch, but we have optimized it for extensions that enable a complete environment for power conversion algorithms and support rapid implementation of the algorithms,” Spinella said.

“Quaregg is a secondary-side controller,” said Spinella. “Compared to a quasi-resonant architecture, we are able to ensure ZVS under a wide range of conditions from 1% load to full load, thus avoiding the burst mode. A controller using active clamping has higher power near full load, but can be reduced at light load, so we remove the high-voltage MOSFET, which is expensive and difficult to design. This means you can derate the secondary-side MOSFET from 100V to 60V and have better EMI, which can reduce the size of the filter and the overall size of the charger.”

“It uses the same silicon MOSFET and switch architecture, the same magnetics, and you can increase efficiency to 93% by just changing the controller to ours,” Spinella said. “That’s the same cost as a flyback architecture and 30% cheaper than an active clamp design because you can reduce the cost of the primary-side MOSFET and the filter.”

Using existing silicon devices and RM8 magnetics, the design consumes 15mW at low load at 115V and 28-30mW at 240V, and moving to GaN could further improve efficiency.

“Switching to GaN can add another 0.5% to 1%, depending on output power and switching frequency. The controller can reach 1MHz with a high-resolution timer we designed to accommodate future needs,” said Spinella.

“We always try to help our customers, and we have a power density of 25W/in3 at 100kHz, so we always try to understand the specs and choose the lowest frequency to meet the performance. In that case, choosing Gan FETs with lower parasitic capacitance for higher frequencies meant we were able to operate at 300 to 400kHz and achieve a power density of 27W/in3, using planar transformers to take full advantage of the high frequency characteristics,” he said.

Isolation between the primary and secondary sides is a key issue for the controller and is handled in different ways depending on customer requirements. “The controller is compatible with three ways of transmitting drive signals, including optocoupler, capacitor isolation, and signal transformer isolation.”

Eggtronic will offer GaN and silicon based QuarEgg+ products with power outputs of 35 W, 45 W and 60 W. Output options include USB PD, fixed voltage and CC CV modes. Development boards, integrated power controllers, a range of proprietary magnetics and comprehensive technical support and manufacturing support will also be available.

“There are a few select companies that ask us to help with mass production, and we provide mass production through CEM and the assembly companies that we like to use, we have Taiwanese, Chinese and a European contract manufacturer – there is a major Italian customer and CEM is European,” Spinella said.

The controller is currently manufactured at TSMC's 180nm process. "This is not the only possible partner, we are exploring other partners. Scaling below 90nm, 65nm could be an option, we haven't decided yet because it is about process availability. We are optimizing costs by scaling the digital part that takes up most of the chip area and halving the chip price without reducing performance."

The company is currently working with OEMs and will be looking at distribution by the end of next year, Spinella said.

“Distribution is still being planned, but at the moment we prefer to find selected key customers to increase sales, increase production capacity and reduce prices. It is expected that distribution may be easier by the end of 2022 when the first customers are in mass production,” Spinella said.