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Charge pump circuit for high side switch

  • US 5,672,992 A
  • Filed: 04/11/1995
  • Issued: 09/30/1997
  • Est. Priority Date: 04/11/1995
  • Status: Expired due to Term
First Claim
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1. A high side switch circuit comprising, in combination:

  • a gate controlled M0S power semiconductor device having first and second power electrodes and a control electrode;

    a charge pump circuit having first and second power terminals and an output terminal;

    a constant current source circuit having input and output terminals;

    a Vcc input voltage terminal connected to said first power electrode of said gate controlled MOS power semiconductor device and connectable to a source of power;

    a load terminal connected to said second power electrode of said gate controlled MOS power semiconductor device and connectable to a grounded load that is capable of being energized from said source of power when said gate controlled MOS power semiconductor device is closed; and

    a ground terminal connectable to said grounded load;

    said charge pump circuit being operable to produce an output voltage at its said output terminal which is higher than said Vcc input voltage;

    said first power terminal of said charge pump circuit being connected with said Vcc input voltage terminal;

    said second power terminal of said charge pump circuit connected to said input terminal of said constant current circuit;

    said output terminal of said constant current circuit connected to said ground terminal, whereby said second power terminal has a floating potential and the currents at said Vcc input voltage terminal and at said ground terminal are constant so that noise at said Vcc input terminal and at said ground terminal is reduced;

    said output terminal of said charge pump circuit being connected to said control electrode of said gate controlled MOS power semiconductor device for providing, in conjunction with said constant current source sinking current from said charge pump, a voltage sufficiently higher than the voltage of said second terminal to turn on said gate controlled MOS power semiconductor device.

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