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High voltage integrated circuit driver for half-bridge circuit employing a bootstrap diode emulator

  • US 5,373,435 A
  • Filed: 11/19/1993
  • Issued: 12/13/1994
  • Est. Priority Date: 05/07/1993
  • Status: Expired due to Fees
First Claim
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1. A circuit for driving a half-bridge formed by lower and upper power transistors connected between an output terminal and respective lower and upper rails of a high voltage DC supply, and for charging a bootstrap capacitor having first and second ends, the first end being connected to said output terminal, said circuit comprising:

  • controller and level shifter means for generating lower and upper drive command signals for commanding driving said respective lower and upper power transistors to noncontemporaneous conducting states;

    power supply means for generating at a power supply output a relatively low control voltage with respect to said lower rail;

    a lower drive module connected to the power supply output for being powered by said relatively low control voltage and comprising means for applying a lower drive control signal between a control electrode of the lower power transistor and the lower rail in response to said lower drive command signal;

    an upper drive module adapted to be connected to the first end of the bootstrap capacitor for being powered by a bootstrap voltage across said bootstrap capacitor and comprising means for applying an upper transistor control signal between a control electrode of the upper power transistor and the output terminal in response to said upper drive input control signal; and

    bootstrap diode emulator means for charging said bootstrap capacitor to said bootstrap voltage, said bootstrap diode emulator means comprising a further transistor having a high current first electrode connected to said power supply output, a high current second electrode adapted to be connected to the second end of the bootstrap capacitor and a control third electrode coupled to a further control signal derived from said lower drive command signal for driving said further transistor to a conducting state when the lower power transistor is driven to a conducting state.

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