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Regulated-current power supply and methods for resistively-heated surgical instruments

  • US 5,445,635 A
  • Filed: 07/06/1994
  • Issued: 08/29/1995
  • Est. Priority Date: 05/01/1992
  • Status: Expired due to Fees
First Claim
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1. Apparatus for performing surgery comprising:

  • a surgical instrument having a resistively-heated heating element;

    a power supply for supplying an alternating current to the heating element, the power supply comprising;

    a current supply circuit having a control terminal for accepting a control signal and having a first current supply circuit output terminal and a second current supply circuit output terminal for supplying the alternating current to the heating element coupled therebetween, the current supply circuit supplying the alternating current to the heating element in response to the control signal;

    a current feedback circuit coupled between the second current supply circuit output terminal and the heating element for monitoring the alternating current as it is supplied by the current supply circuit, the current feedback circuit having a current feedback terminal for supplying a current feedback signal indicative of a magnitude of the alternating current as it is monitored by the current feedback circuit;

    an error amplifier having a first error amplifier input for accepting a set-point signal, a second error amplifier input for accepting the current feedback signal, and an error amplifier output terminal for coupling the control signal, indicative of a difference between the set-point signal and the current feedback signal, to the control terminal of the current supply circuit, the error amplifier output terminal being coupled to the control terminal of the current supply circuit; and

    means for generating the set-point signal, the means for generating the set-point signal having a set-point output terminal coupled to the first error amplifier input, wherein the set-point signal is indicative of a predetermined magnitude of the alternating current corresponding to a predetermined heating element operating temperature and so that the alternating current supplied to the heating element is regulated to the predetermined magnitude set by the set-point generating means.

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