Image

Flyback Synchronous Rectifier Driver Delivers 10-A Output

March 6, 2014
Linear Technology’s LT3809 flyback secondary-side synchronous rectifier driver replaces the output diode forward-voltage drop with the RDS(ON) of an external N-channel MOSFET, thus reducing the power loss and allowing up to 10 A output current without a heatsink.

Maximum output current of a typical flyback power supply is limited by the power loss and heat generated from the output diode when there’s no heatsink. Linear Technology’s LT3809 flyback secondary-side synchronous rectifier driver replaces the output diode forward-voltage drop with the RDS(ON) of an external N-channel MOSFET, thus reducing the power loss and allowing up to 10 A output current without a heatsink. The device senses the MOSFET’s drain-to-source voltage for activation, which eliminates the transformer and allows it to work with the company’s no-opto-coupler products for output-voltage-feedback boundary-conduction-mode (BCM)/critical-conduction-mode (CrCM) flyback converters. Operating input voltage ranges from 4.5 to 40 V, and a 500-µA quiescent current helps maximize light load efficiency. A 1-Ω pull-down gate driver accelerates device turn-off, while low minimum on- and off-times boost noise immunity. Other features include a 22-ns propagation delay, adjustable and accurate trip voltage, and the ability to drive 150-V-rated MOSFETs. The rectifier comes in a 5-lead SOT23 package.

LINEAR TECHNOLOGY CORP.

About the Author

Staff

Articles, galleries, and recent work by members of Electronic Design's editorial staff.

Sponsored Recommendations

Comments

To join the conversation, and become an exclusive member of Electronic Design, create an account today!