| 摘要 |
A four-terminal MOSFET, in which no combination of the source, drain, body and gate terminals are permanently connected together, is used as a synchronous rectifier capable of blocking an excessive current in a switching mode DC-DC converter resulting from a short-circuited load. In an N-channel version of the synchronous rectifier, the MOSFET body terminal is normally connected to the inductor in the DC-DC converter and is grounded when an overcurrent condition is detected. In a P-channel version of the synchronous rectifier, the MOSFET body terminal is normally connected to the converter output and is connected to the inductor when an overcurrent condition is detected. In addition, the voltage output by the inductor may be clamped using a zener diode or a snubber capacitor. A MOSFET body bias switching circuit is driven by overcurrent detection circuitry that may also be used to turn off the synchronous rectifier MOSFET gate.
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