3
\$\begingroup\$

I found the only isolated gate driver on the market! It's all perfect, only doesn't have the deadtime circuit - the other part number is out of stock.

I am willing to change the layout and add my own circuit, but it should be cheap, it's a big batch. It should also be reliable for the same reason.

I thought about logic and delays with an RC circuit (has to be at least 200nsec, so not just a buffer for the delay,) but it seems odd.

Are there other ideas?

2EDF7275K driver datasheet

The current decision is to go with a logic buffer and a small (160MHz) filter on the command lines.

enter image description here

\$\endgroup\$
33
  • 1
    \$\begingroup\$ Does this answer your question? Driving low voltage P-MOS N-MOS half bridge with dead time control, without bootstrap and one control line \$\endgroup\$
    – Andy aka
    Commented Feb 18, 2022 at 15:46
  • 5
    \$\begingroup\$ I'm not sure I see the risk. Just do the deadtime in the MCU's PWM module. If EMI is enough to fire gates then you have bigger problems since everything else is going glitch too. Deal with the EMI through layout. How long is long? Why are your gate driver so far from the gates? That's the EMI causing problem, not dead time. \$\endgroup\$
    – DKNguyen
    Commented Feb 18, 2022 at 15:57
  • 3
    \$\begingroup\$ "Are there other ideas?" Here are two wild and crazy ideas: a) Post your schematic. b) tell us the part number of the gate driver you found. \$\endgroup\$
    – AnalogKid
    Commented Feb 18, 2022 at 16:11
  • 1
    \$\begingroup\$ It has Schmidt trigger inputs. I would maybe just add series termination resistors, but on both ends. If you're real worried leave room for a cap to ground next to the input, but do not populate. This has nothing to do with deadtime so I don't know why you call it that. It's just filtering. \$\endgroup\$
    – DKNguyen
    Commented Feb 18, 2022 at 16:15
  • 1
    \$\begingroup\$ The datasheet of the part that has the order number in it that you quoted shows dead time control. This MAY not be in all versions. You do yourself less than zero good by not being specific about the part you are using to a level of detail where we can understand the actual question. \$\endgroup\$
    – Russell McMahon ♦
    Commented Feb 19, 2022 at 23:45

1 Answer 1

Reset to default
1
\$\begingroup\$

has to be at least 200nsec, so not just a buffer for the delay

Not all logic is as fast as you think :) The CD4000 logic family will produce the delays you want if you run it from a low enough voltage. Since you seem to be running 3V logic, the CD4000B gates will have delay in the right ballpark without additional RC components. You can use that delay to produce dead-time.

\$\endgroup\$
3
  • \$\begingroup\$ alright, that's an idea indeed, thank you! though i am not sure it's more accurate than an RC filter :))) \$\endgroup\$
    – TQQQ
    Commented Feb 20, 2022 at 0:33
  • \$\begingroup\$ Whatever you’re using that driver for is probably running closed loop. The exact duration of the dead time is perhaps not as critical as you think :) \$\endgroup\$
    – Kuba hasn't forgotten Monica
    Commented Feb 20, 2022 at 0:34
  • \$\begingroup\$ true... still, this is a type of things that if it does have an effect, it's hard to understand what's going on and fix it. \$\endgroup\$
    – TQQQ
    Commented Feb 20, 2022 at 0:39

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.