SAN FRANCISCO — Mobile devices have gotten slimmer over the years but chargers have remained in the same clunky form factors. Zolt, a subsidiary of gallium nitride (GaN) fab Avogy, has developed a lipstick tube sized charger capable of powering three devices at once at up to 70 Watts.
Zolt’s power converters allow users to charge batteries of different sizes simultaneously without overheating or experiencing large switching losses. The Zolt Laptop Charger Plus can maintain a skin temperature of 63 degrees and is efficient enough dissipate power and save 5-8 degrees in the adapter.
Zolt's designers hope to replace bulky batteries with a much smaller multi-device charger. Source: Avogy
The device can power any laptop and two USB-based devices with range of 110V to 240V. An onboard microcontroller runs firmware to identify devices and route a specified amount of current through each of the devices ports, said Poonacha Kongetira, Avogy vice president of systems engineering.
To negate switching losses that typically occur in switch board power supplies, the Zolt Laptop Charger Plus switches the FET when voltage across the device is zero. A wide bandgap semiconductor such as GaN is an excellent fit for heavily modulated power cycling, Kongetira said, noting that you could feed 1,200 V into the semiconductor without degrading reliability.
GaN can also operate at very high frequencies, which allows Zolt to use a resonant tank circuit that oscillates at its own frequency.
“If you operate a device at a higher frequency than the resonant frequency of this tank, you get zero voltage switching. This circuit voltage tech allows us to be very efficient,” Kongetira said.
While the primary consumer need is in charging devices, Avogy officials expect high voltage frequency GaN to fit any market where AC power needs to be converted down – from servers to windmills and data centers where high voltage devices could be made smaller and cooler.
— Jessica Lipsky, Associate Editor, EE Times