×

Constant-Current Control Module using Inverter Filter Multiplier for Off-line Current-Mode Primary-Side Sense Isolated Flyback Converter

  • US 20110216559A1
  • Filed: 03/05/2010
  • Published: 09/08/2011
  • Est. Priority Date: 03/05/2010
  • Status: Active Grant
First Claim
Patent Images

1. A power converter comprising:

  • a transformer having a primary winding that receives an input voltage and outputs a drain voltage on a drain node, the transformer also having a secondary winding that outputs a secondary current that is induced by mutual induction from changes in a primary current through the primary winding;

    a switch that receives the primary current from the transformer at the drain node, and is controlled by a gate voltage to switch the primary current to a primary-sensing node, wherein the switch is a metal-oxide-semiconductor field-effect transistor (MOSFET);

    a primary sensing resistor coupled to the primary-sensing node and generating a primary-sensing voltage on the primary-sensing node when the switch connects the primary current to the primary sensing resistor;

    a bistable latch that generates a switch signal that controls the gate voltage to the switch;

    a reset comparator that receives the primary-sensing voltage and receives a feedback voltage, and generates a reset signal to the bistable latch when the primary-sensing voltage crosses the feedback voltage;

    wherein the reset signal resets the bistable latch to deactivate the switch signal and drive the gate voltage to a disabling voltage that causes the switch to isolate the transformer from the primary sensing resistor;

    a multiplier that receives the switch signal from the bistable latch and receives the feedback voltage, the multiplier multiplying the feedback voltage by an off duty cycle indicated by a ratio of a time that the switch signal is inactive to a period of the switch signal to generate a filtered voltage;

    an error amp that receives the filtered voltage from the multiplier and receives a reference voltage, the error amp comparing the filtered voltage to the reference voltage to generate the feedback voltage; and

    a set signal that sets the bistable latch to activate the switch signal and drive the gate voltage to an enabling voltage that causes the switch to conduct the primary current from the transformer to the primary sensing resistor,whereby the primary current is switched to control the secondary current.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×