High efficiency and small form factor in ZVS power-supply ICs

Power Integrations has released its InnoSwitch4-Pro family of digitally controllable, off-line CV/CC ZVS flyback ICs, which greatly reduce the size of power adapters. Integrating a robust PowiGaN gallium-nitride primary switch and steady-state switching frequency of up to 140kHz, the highly integrated devices lower the component count and PCB area needed for ultra-compact adapters for cellphone, notebook, tablet and multi-port accessories.

"InnoSwitch4-Pro ICs interface seamlessly with Power Integrations' ClampZero family of active clamp ICs to achieve ZVS in both continuous conduction mode and discontinuous conduction mode," stated Aditya Kulkarni, product marketing manager at Power Integrations. "ZVS, combined with our PowiGaN technology, virtually eliminates switching losses. Efficiency exceeds 95%, which enables designers to eliminate the heat sinks, spreaders and potting materials typically required for thermal management."

Further size reduction of the adapter can be attained by using a MinE-CAP device together with InnoSwitch4-Pro and ClampZero ICs. Based on PowiGaN technology, these ICs allow input capacitance size reduction of approximately 40%.

Capable of producing up to 220W, the ICs combine a 750V PowiGaN primary switch, controller, FluxLink reinforced isolation feedback link for secondary-side control, I2C interface, active clamp drive and synchronous rectification in a compact InSOP-28 package. The high level of integration hugely simplifies the development and manufacturing of fully programmable, highly efficient power supplies. These programmable flyback ICs together with ClampZero and MinE-CAP companion devices, allow the ultra-compact and slim form factors highly desired by OEM accessory and aftermarket USB PD and UFCS adapters.

The ICs use a unique control algorithm to allow ZVS in DCM and CCM. When paired with the ClampZero IC, the algorithm provides higher-frequency operation with no corresponding drop in efficiency. It also supports quasi-resonant switching in DCM and CCM when utilised as a standalone product. DCM-only operation can be chosen to lower SR FET voltage stress. The new ICs also provide an optimised command set to reduce I2C traffic.

The flyback switcher ICs supply exceptional CV/CC accuracy, independent of external components, and consume less than 30mW no-load while providing line-sensing and comprehensive protection features. Devices are fully protected, featuring auto-restart or latching fault response for output overvoltage and undervoltage protection, multiple output undervoltage fault thresholds, and latching or hysteretic primary over-temperature and output bus switch short-circuit protection.