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UCC27284-Q1: Half-Bridge Gate Driver to Drive a High Side Back-to-Back N-MOSFETs

Part Number: UCC27284-Q1
Other Parts Discussed in Thread: UCC27284

Dear TI Team,

this is regarding an application circuit of : Half-Bridge Gate Driver to Drive a High Side Back-to-Back N-MOSFETs (in Common-Source Configuration)

When we disabled HI, we have following observations

  1. HO is taking ~200mS to become 0V even though Vgs becomes 0V in 1uS
  2. And MOSFET output is following HO.

attached Schematic and waveforms for your kind reviewUCC27284-Q1 Schematic & Test Results.docx

  • Hi,

    Thank you for your question. Could you please clarify if HO is measured with respect to GND or with respect to HS? HO should be measured with respect to HS since that is the voltage from gate to source of the FET. 

    Best regards,

    Leslie

  • Hi Leslie

    Thanks for your response.

    HO is measured with respect to GND.
    for us MOSFET Output following HO is concern as its taking ~200mS to become 0V

  • Hi, 

    Thanks for clarifying. The charge pump capacitor (C14 in your schematic) has to charge and discharge as HS moves up and down, and if you are testing with high impedance at the output of the switch then the discharge of the capacitor can be slow. I would suggest to try testing with an output load so the capacitor can discharge faster. 

    Best regards,

    Leslie