UCC24624 Synchronous Rectifier (SR) Controller
Texas Instruments UCC24624 Synchronous Rectifier (SR) Controller is dedicated to LLC resonant converters to replace the lossy diode output rectifiers with SR MOSFETs and improve the overall system efficiency. The UCC24624 SR controller uses a drain-to-source voltage sensing method to achieve on-and-off control of the SR MOSFET. A proportional gate drive is implemented to extend the SR conduction time and minimize the body diode conduction time. To compensate for the offset voltage caused by the SR MOSFET parasitic inductance, the UCC24624 implements an adjustable positive turn-off threshold to accommodate different SR MOSFET packages. UCC24624 has a built-in 475ns on-time blanking and a fixed 650ns off-time blanking to avoid SR false turn-on and turn-off. UCC24624 also integrates a two-channel interlock function that prevents the two SRs from being on simultaneously. With 230V voltage-sensing pins and 28V ABS maximum VDD rating, it can be directly used in converters with output voltage up to 24.75V. The internal clamp allows the controller to support 36V output voltage easily by adding an external current limiting resistor on VDD.
