I'm designing a buck converter based on TL494. And I have to drive high side mosfet, i want to use a gate drive transformer, switched by totem pole driver. simple drive method The problem is that slopes of signal coming out at collector are (i think) very bad. (>100ns) I want to drive mosfet with slopes <50ns, and signal will get only worse in transformer etc. Problem is really visible with low duty cycle (signal has almost triangle shape). Also tried with TL494 on high side, and R3 on low side. I can post scope images. I am thinking right? Could i get better slopes from TL494?

  • 2
    \$\begingroup\$ Why not use a high side MOSFET driver and rid your self of this headache. \$\endgroup\$
    – Andy aka
    Commented Apr 6, 2020 at 11:59
  • \$\begingroup\$ Yes, i could use mosfet driver, but now i cannot buy it anywhere. I'm also learning now, so i want to do it old shool way, however when wont be able to get this working i will probably use integrated driver. On the other hand mosfet driver also needs sharp slopes... \$\endgroup\$
    – fifi_22
    Commented Apr 6, 2020 at 12:18
  • \$\begingroup\$ Make R3 lower in value and note that it's a push pull driver and not a totem pole type. \$\endgroup\$
    – Andy aka
    Commented Apr 6, 2020 at 12:29
  • \$\begingroup\$ I tried it, and even 470ohm is not low enough. It doesnt make any significant change and the power consumption gets horrible like 100mA. \$\endgroup\$
    – fifi_22
    Commented Apr 6, 2020 at 12:45
  • 4
    \$\begingroup\$ To me this looks like "using old skool components to try and make a modern circuit". Look at the datasheet of the TL494, it specifies rise/fall times up to 100 or 200 ns. What does a circuit for driving MOSFETs with slopes less than 50 ns look like? Why do you think you can achieve that using technology that gets much slower rise/fall times and is only used at low switching frequencies? In my opinion you're just wasting your time to make this do what you want. Learn how everyone else drives MOSFET stages and build something like that. \$\endgroup\$ Commented Apr 6, 2020 at 12:51

1 Answer 1


get a faster switching transistor like 2n2222 instead of bc337.You will get faster rise and fall times


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