• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 64 subscribers
  • Views 157 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

UC1825B-SP: Need to create a SPACE Power supply - Grade LLC Controller 500W. I'm stuck between a UC1825B-SP and UC1875-SP...

UC1875-SP: Learning to use the UC1875-SP, need explanation from document.

Thomas Flack2
Prodigy 60 points
Part Number: UC1875-SP

As stated earlier, I have decide to go with the UC1875-SP, Phase Shift Resonant Controller. I am now reading the document "Phase Shifted Full Bridge Zero Voltage Transition Design  considerations"

Phase Shifted Full Bridge, Zero Voltage Transition Design Considerations (Rev. A)

As I read this document, just so my understanding is clear, I see on page 9, last paragraph, first sentence:

"Primary current continues to flow and is clamped by the body diode of switch QB, which is still OFF."

Shouldn't this say:

Primary current continues to flow and is clamped by the output capacitance of switch QB, which is still OFF.

Note, the diode is not conducting (Figure 12) - which is not numbered, therefore it cant be doing the clamping.

Thanks for the help.

Thomas

  • 0
    TI__Mastermind 26395 points

    Hey Thomas,

    I think perhaps the paragraph is a bit misleading. What is really meant is that the primary current will continue to flow and the voltage dip will be clamped by the body diode.

    There is a voltage dip that allows for zero voltage switching created by parasitics, and depending on the parasitics will either swing not all the way to zero, giving partial zero voltage switching, or swing "too low" and get clamped at the body diode to ~-0.7 V. Either way I believe voltage is clamped here not current.

    Thanks,

    Daniel