ISOLATED HIGH-VOLTAGE DC-DC CONVERTER HYSTERETIC BURST MODE NOISE IMMUNITY USING DYNAMIC HYSTERESIS

A DC-to-DC converter having primary- and secondary-side circuitry separated by an isolation barrier, with a transformer and a feedback lane across the barrier, uses a dynamic function current source in its secondary-side circuitry to dynamically adjust the hysteresis threshold only at the transformer burst turn-off edge to provide enhanced immunity to transformer switching noise. An output voltage of the converter (or signal based thereon) is compared to the threshold to provide an input to a timing pulse generator that closes a switch to couple the dynamic function current source into voltage threshold setting circuitry. The dynamic function current source can reduce the threshold to a level that avoids chattering in transformer burst turn-off feedback signal caused by the noise, for a duration that can be based on lane delay of the converter and to an amplitude that can be based on the expected maximum negative amplitude of the noise.