As energy standards like DOE Level VII and the EU Ecodesign Directive grow more stringent, power design engineers are tasked with maximizing density while minimizing standby loss. Leadtrend addresses this with the new LD7711, an AHB Flyback controller featuring innovative resonant current modulation. Designed for USB PD3.2 high-power adapters, the LD7711 resolves the common problem of startup current surges during rapid restarts, a feat documented in the IEEE JESTPE journal.
Moving away from inefficient passive bleeder resistors, the LD7711 uses active monitoring via auxiliary windings and the FB pin. If it detects dangerous negative resonant current during a restart, it dynamically adjusts pulse timing to kill current spikes, shielding GaN and MOSFET components from stress. The LD7711 is a high-performance SOP-16 chip featuring ZVS, 300kHz switching, and integrated safety functions like X-Cap discharge and 700V startup. It anchors a complete 240W ecosystem that includes Leadtrend’s PFC controllers, synchronous rectifiers, and PD protocol chips for a seamless power delivery solution.
In 240W PD3.2 prototype testing, Leadtrend’s technology slashed peak negative startup current by over 50%—from 20A down to 10A—during 8ms AC interruptions. Plus, by removing the need for bleeder resistors, standby power consumption dropped by 29.3mW at 48V. It’s a major step forward for reliable, high-density, and eco-friendly power adapter design.
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