Control circuit for isolated forward DC-to-DC converters

摘要

An isolated DC-to-DC converter comprises a converter section configured to receive an input voltage and produce an isolated output voltage and a controller section configured to control the operation of the converter section to maintain the output voltage at a predetermined value by, at least in part, turning switches on and off at a certain duty cycle at a set switching frequency. The controller section comprises an isolation transformer providing primary and secondary side isolation and an error amplifier having an output coupled to the isolation transformer, the error amplifier providing an error signal that is representative of the difference between an output voltage and a desired output voltage. The converter further comprises an isolation driver coupled to an isolation driver switch, the isolation driver operable to turn on and off the isolation driver switch at the same frequency as the converter section, the switching of the isolation driver switch resulting in the error signal becoming an amplitude modulated error signal that is transferred across the isolation transformer.