Diodes Incorporated's new AP3301 quasi-resonant (QR) PWM controller enables high-performance, cost-effective power supplies capable of meeting DOE6 / COC Tier 2 efficiency requirements at all load levels.
This controller is aimed at the main market of AC / DC adapters for set-top box and game console applications. The controller meets the auxiliary power requirements of ATX / BTX computer motherboards, and is especially suitable for open frame switching power supplies.
Multiple working modes enable the AP3301 to achieve optimal efficiency at different load levels: Under low load or no-load conditions, the IC uses burst mode to minimize standby power consumption, while at the same time with a minimum switching frequency of about 20kHz Work to avoid audible noise. Under medium load, the valley-locked QR mode with frequency foldback improves efficiency and EMI performance. For heavy loads or under low-voltage input conditions, the controller enters continuous conduction mode (CCM) at a fixed 62kHz switching frequency to achieve the best conversion efficiency. The built-in frequency jitter function helps reduce EMI emissions in CCM and QR modes.
AP3301 provides comprehensive protection functions to enhance system reliability. These include: AC input under-voltage protection, cycle-by-cycle current limit, accurate output over-voltage protection, internal over-temperature protection, overload protection, and pin fault protection circuit, which can detect floating or short-circuited key signal pins and disable PWM Switch to protect the power system.
With only a few changes, the externally packaged SOT-26 AP3301 can provide the company's existing AP3105 / AP3125 PWM controller with a pin-compatible replacement solution.
