Ericsson Gmbh

Mark N Sun

William Hart

A converter with synchronous rectification is driven in such a way so that the reverse currents do not build up and cause damage to or limit the efficiency of the circuit. Negative currents are self-adjusted to a very small percentage of load current, so the converter will not have problems when in parallel with other modules. An auxiliary winding is used to allow an output inductor to drive the secondary side rectifiers thereby limiting their conduction time as reverse currents increase. The primary side conduction times are extended by operation of their anti-diodes so that reverse currents are limited naturally without the use of dedicated load sensing and shutdown circuits.

Reducing reverse currents in a synchronous rectifier circuit

A rectifier circuit having voltage clamping circuitry is disclosed. The rectifier circuit includes a transformer having a primary winding and a secondary winding and transistor switches each being connected to an end of the secondary winding of the transformer. The rectifier circuit further includes a first diode having an anode terminal connected to a first end of the secondary winding and a second diode having an anode terminal connected to a second end of the secondary winding. The cathode terminals of the first and second diodes are coupled to a capacitor. The energy stemming from voltage spikes and/or high frequency ringing appearing at the transistor switches due to parasitic effects is effectively absorbed by the first and second diodes and collected in the capacitor. The collected energy is recycled to control the operation of the transistor switches.

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Mark N Sun