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Integrated circuit for controlling power converter by frequency modulation and pulse width modulation

  • US 4,685,040 A
  • Filed: 12/06/1985
  • Issued: 08/04/1987
  • Est. Priority Date: 12/06/1985
  • Status: Expired due to Term
First Claim
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1. An integrated circuit for driving the converter switches of and controlling at least one output voltage of a DC to DC converter, said integrated circuit comprising:

  • a first control loop including a first amplifier, a voltage-controlled oscillator, and connection means for permitting the output of said first amplifier to be coupled with the input of said voltage-controlled oscillator, the output of said voltage-controlled oscillator comprising the output of said first control loop;

    a second control loop including a second amplifier coupled to a first comparator, said first comparator also being coupled to the output of said voltage-controlled oscillator, the output of said comparator comprising the output of said second control loop;

    logic means connected to the output of each of said first and second control loops, respectively, for generating a pair of switching signals at first and second outputs thereof, respectively, each of said switching signals having a frequency in accordance with the output signal from said first control loop and having a duty ratio in accordance with the output signal from said second control loop; and

    a driver circuit coupled to the first and second outputs of said logic means, said driver circuit having outputs for driving a first converter switch and a second converter switch, said driver circuit adapted to be coupled to an external capacitor for providing a voltage sufficient to drive said second converter switch.

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