L6565DTR

The L6565DTR from STMicroelectronics is an advanced monolithic current-mode primary controller specifically engineered for quasi-resonant flyback converters. This component enables zero-voltage switching through transformer demagnetization sensing, significantly reducing switching losses and electromagnetic interference. It provides an efficient power management solution for high-efficiency AC-DC adapters and consumer electronics.

Key electrical specifications include an operating voltage range of 10.3V to 18V, with a low start-up current of less than 45 microamps. The output drive capability is rated at 400mA source and 700mA sink. The device features a proprietary line feed-forward function for constant power delivery across mains voltage variations and integrated protection circuits like programmable overvoltage protection and pulse-by-pulse current limiting.

This controller operates on a variable frequency control principle. At high loads, it uses Quasi-Resonant mode, triggering the power MOSFET at the drain voltage valley to minimize turn-on losses. As the load decreases, it transitions to a frequency foldback mode to maintain high efficiency. The L6565DTR is housed in an 8-SOIC package and is designed for surface mount applications.

Its design advantages include elite switching efficiency due to quasi-resonant switching, ultra-low power consumption, and comprehensive protection features, making it a robust choice for safety-critical SMPS designs.