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Temperature compensation in output feedback of a flyback power converter

  • US 8,351,223 B2
  • Filed: 07/19/2010
  • Issued: 01/08/2013
  • Est. Priority Date: 07/22/2009
  • Status: Expired due to Fees
First Claim
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1. A secondary circuit of a flyback power converter including a capacitor connected between an output end and a ground end to supply an output current, and a secondary coil of a transformer to provide a secondary current for charging the capacitor, the secondary circuit comprising:

  • a resistor network connected in a path of the output current to generate a voltage according to the output current, the resistor network comprising;

    a current sense resistor connected between the ground end and the capacitor;

    a resistor and a thermistor connected in series to each other and connected in parallel to the current sense resistor; and

    a bipolar junction transistor having a base connected to the resistor network to receive the voltage and providing a collector signal for output feedback;

    wherein the resistor network has a resistance varying with temperature to compensate for a temperature effect of a base-emitter voltage of the bipolar junction transistor on the output current.

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