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Two-Phase Interleaved CCM PFC Controller


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To introduce the UCC28070 two-phase interleaved CCM PFC Controller and its basic operation

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Two-Phase Interleaved CCM PFC Controller

  1. 1. Two-Phase Interleaved CCM PFC Controller <ul><li>Source: T EXAS I NSTURMENTS </li></ul>
  2. 2. Introduction <ul><li>Purpose </li></ul><ul><ul><li>To introduce the UCC28070 two-phase interleaved CCM PFC Controller and its basic operation. </li></ul></ul><ul><li>Outline </li></ul><ul><ul><li>PFC basics </li></ul></ul><ul><ul><li>Overview of the UCC28070 </li></ul></ul><ul><ul><li>Basic operations of the UCC28070 </li></ul></ul><ul><ul><li>Summary </li></ul></ul><ul><li>Content </li></ul><ul><ul><li>16 pages </li></ul></ul>
  3. 3. Power Factor Correction (PFC) Basics <ul><li>PFC is simply defied as the ratio of real power to apparent power </li></ul><ul><li>Passive PFC – requires bulky 60-Hz iron core inductors </li></ul><ul><li>Active PFC – smaller than passive PFC </li></ul>
  4. 4. Why Interleave PFC? <ul><li>Input and output ripple current cancellation </li></ul><ul><ul><li>Reduces boost inductor volume </li></ul></ul><ul><ul><li>Reduces output capacitor RMS current </li></ul></ul><ul><ul><li>Reduces the EMI filter size </li></ul></ul>
  5. 5. UCC28070 Two-Phase Interleave PFC <ul><li>Key Features </li></ul><ul><ul><li>Interleaved average current mode PWM control </li></ul></ul><ul><ul><li>Advanced current synthesizer for superior efficiency, accurate current sensing and high power factor </li></ul></ul><ul><ul><li>Highly linear multiplier output with internal voltage feed-forward correction for near unity power factor </li></ul></ul><ul><ul><li>Programmable switching frequency (30 kHz to 300 kHz) </li></ul></ul><ul><ul><li>Selectable frequency dithering for reduced EMI </li></ul></ul><ul><ul><li>Phase management for high-efficiency light-load operation </li></ul></ul><ul><li>Key Applications </li></ul><ul><ul><li>High end servers </li></ul></ul><ul><ul><li>Base stations </li></ul></ul><ul><ul><li>Data centers </li></ul></ul><ul><ul><li>HVAC </li></ul></ul><ul><ul><li>White goods </li></ul></ul><ul><ul><li>Motor control </li></ul></ul>
  6. 6. Ripple Current Reduction <ul><li>Delivers output and input ripple cancellation </li></ul><ul><ul><li>Reduce design size and cost </li></ul></ul><ul><ul><li>Increase power capability of already established design size </li></ul></ul>
  7. 7. Frequency Dithering <ul><li>The desired dither magnitude is set by a resistor from the RDM pin to GND. </li></ul><ul><li>Once the value of RRDM is determined, the desired dither rate may be set by a capacitor from the CDR pin to GND. </li></ul><ul><li>Frequency dithering may be fully disabled by forcing the CDR pin > 5 V or by connecting it to VREF (6 V) and connecting the RDM pin directly to GND. </li></ul>
  8. 8. Current Synthesizer <ul><li>The current synthesizer circuitry synchronously monitors the instantaneous inductor current. </li></ul><ul><li>Setting up the current synthesizer is accomplished by correctly selecting R SYN . </li></ul>
  9. 9. Peak Current Limit <ul><li>A programmable cycle-by-cycle peak current limit dedicated to disabling either GDA or GDB output whenever the corresponding current-sense input rises above the voltage established on the PKLMT pin. </li></ul><ul><li>A resistor-divider network from VREF to GND can program the peak current limit voltage on PKLMT. </li></ul>
  10. 10. Linear Multiplier Linear Multiplier Architecture
  11. 11. Multi-phase Operation Synchronized clock
  12. 12. Current Loop Compensation <ul><li>The current control loop comprises </li></ul><ul><ul><li>Boost power plant stage </li></ul></ul><ul><ul><li>Current sensing circuitry </li></ul></ul><ul><ul><li>Wave-shape reference </li></ul></ul><ul><ul><li>Current-error amplifier with compensation components </li></ul></ul>
  13. 13. Voltage Loop Compensation <ul><li>The bandwidth of the voltage-loop must be considerably lower than the twice-line ripple frequency (f 2LF ) on the output capacitor, to avoid distortion-causing correction to the output voltage. </li></ul><ul><li>The output of the voltage-error amplifier adjusts the input current amplitude relative to the required output power. </li></ul>
  14. 14. Other Protection Features <ul><li>Over-Voltage Protection (OVP) </li></ul><ul><ul><li>When V VSENSE rises above 106% of regulation (3.18 V) </li></ul></ul><ul><ul><ul><li>the GDx outputs are immediately disabled </li></ul></ul></ul><ul><ul><ul><li>the CAOx outputs are pulled low </li></ul></ul></ul><ul><li>Zero-Power Detection </li></ul><ul><ul><li>To prevent undesired performance under no-load and near no-load conditions </li></ul></ul><ul><li>Thermal Shutdown </li></ul><ul><ul><li>When the die temperature rises above 160°C </li></ul></ul><ul><ul><ul><li>Internal temperature-sensing comparator shuts down nearly all of the internal circuitry </li></ul></ul></ul><ul><ul><ul><li>The GDA and GDB outputs are disabled </li></ul></ul></ul>
  15. 15. Summary <ul><li>Input and output ripple current cancellation </li></ul><ul><ul><li>Reduce boost capacitor RMS current </li></ul></ul><ul><ul><li>Attenuates inductor ripple current at the converter’s input </li></ul></ul><ul><li>Can increase power density </li></ul><ul><ul><li>Reduce inductor volume </li></ul></ul><ul><ul><li>Reduce the size of the EMI filter </li></ul></ul><ul><li>Interleaving can improve efficiency and/or allow the designer to use lower power/cheaper components in their designs </li></ul>
  16. 16. Additional Resource <ul><li>For ordering the UCC28070, please click the part list or </li></ul><ul><li>Call our sales hotline </li></ul><ul><li>For additional inquires contact our technical service hotline </li></ul><ul><li>For more product information go to </li></ul><ul><ul><li> </li></ul></ul>Newark Farnell