SOFT TRANSITION APPARATUS AND METHOD FOR SWITCHING POWER CONVERTERS

摘要

A soft transition apparatus comprises a secondary synchronous rectifier (110) and a secondary gate drive controller (102). The secondary synchronous rectifier (110) comprises a forward switch (QFR) and a freewheeling switch (QFW). The secondary gate drive controller (102) coupled to a transformer winding comprises a secondary synchronous rectifier soft start signal generator configured to generate a plurality of soft start pulses, a pulse width modulation (PWM) generator configured to generate a forward switch drive signal and a freewheeling switch drive signal based upon a signal across the transformer winding and a soft transition generator configured to generate a soft start freewheeling switch drive signal by gradually releasing the freewheeling switch drive signal during a soft start process.