I am working on a half-bridge simulation in LTspice. For the gate drive circuit I am working with an IR2110. My problem is that whatever I select Vin to be above 200 V output, it can't pass 200 V.

I am attaching output voltage waveform for the case where Vin is 300 V. I think the problem is that the high-side switch can't turn on fully. I am attaching the high-side switch DS voltage in the 2nd picture. Any suggestion?

Output Voltage


LtSpice SCH

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    \$\begingroup\$ I can't find your diode. Is it clamping at 200 V reverse voltage by any chance? \$\endgroup\$
    – winny
    Commented Feb 27 at 9:00
  • 2
    \$\begingroup\$ It's a classic, designers way oversize the bootstrap capacitor. Its value depends on the charge evacuated cycle-by-cycle to bias the high-side transistor. It is usually 100 nF, not 15 µF which could not be properly charged in a real circuit. Same for the gate-source resistance which serve for safety but absorb current. Increase them to 22 or 47k, it's good enough. Don't forget to add deadtime for the input clocks. \$\endgroup\$ Commented Feb 27 at 10:06

1 Answer 1


My problem is that whatever I select Vin to be above 200 V output, it can't pass 200 V

The absolute maximum reverse voltage rating for the bootstrap diode (RF081L2S) is 200 volts. That's your problem: -

enter image description here

  • 1
    \$\begingroup\$ Yes sir. I missed it. Thanks. \$\endgroup\$
    – MSB
    Commented Feb 27 at 9:10
  • \$\begingroup\$ I got zero hits for "DRF081L2S". What was the secret google-fu to remove the D? \$\endgroup\$
    – winny
    Commented Feb 27 at 11:56
  • \$\begingroup\$ @winny correct. \$\endgroup\$
    – Andy aka
    Commented Feb 27 at 12:00
  • \$\begingroup\$ How did you come up with it? Removing PBF or packaging information as a suffix is given, but how did you come up with D being a prefix to be removed? \$\endgroup\$
    – winny
    Commented Feb 27 at 12:03
  • \$\begingroup\$ I remembered using a diode beginning with "RF" and thought I'd try it @winny \$\endgroup\$
    – Andy aka
    Commented Feb 27 at 12:08

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