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Bootstrap diode emulator with dynamic back-gate biasing and short-circuit protection

  • US 20060044051A1
  • Filed: 08/19/2005
  • Published: 03/02/2006
  • Est. Priority Date: 08/24/2004
  • Status: Abandoned Application
First Claim
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1. A bootstrap diode emulator circuit for use with a half-bridge switching circuit, the switching circuit including low-side and high-side transistors connected to one another in a totem pole configuration at a load node, the low-side and high-side transistors having respective gate nodes;

  • a driver circuit electrically coupled to the gate nodes of the low-side and high-side transistors, the driver circuit being controllable by at least one control input;

    a low-side voltage supply to produce a low-side voltage on a low-side supply node; and

    a bootstrap capacitor coupled between a high-side supply node and the load node, the bootstrap diode emulator circuit comprising;

    an LDMOS transistor having a gate, a back-gate, a source and a drain, the drain of the LDMOS transistor being coupled to the high-side supply node, the source of the LDMOS transistor being coupled to the low-side supply node;

    a gate control circuit electrically coupled to the gate of the LDMOS transistor, wherein the gate control circuit is operable to turn on the LDMOS transistor in accordance with the at least one control input; and

    a protection circuit which senses the voltage at the load node, prevents turn-on of said LDMOS transistor when the load voltage is not low, and turns off the LDMOS transistor if the load voltage goes high while said control input is also high.

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