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I have been trying to create a buck converter with the IR2104 and two TK2R4A08QM transistors, but it seems that the high side MOSFET can't cope with the load and gets too hot. I probed the gate voltages with my oscilloscope and they look like this:

enter image description here

Below is my schematic. I think I have low-enough gate resistors, and also reverse diodes.

enter image description here

The layout of the relevant part:

enter image description here

Is there something I am doing completely wrong here, or something that I can improve? Any suggestions are welcome!

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    \$\begingroup\$ Looks like you have some shoot trough. Also, can you show board layout? \$\endgroup\$ Commented Aug 25, 2022 at 7:53
  • \$\begingroup\$ I added it in the main question body! \$\endgroup\$
    – HarKal
    Commented Aug 25, 2022 at 8:12
  • \$\begingroup\$ Layout does not look too bad (gate traces and Vs return are somewhat long). I'd try increasing R1 and R2 first to get rid of the shoot trough. (The little kinks in the blue waveform where it crosses the yellow one - they should not cross). \$\endgroup\$ Commented Aug 25, 2022 at 8:26
  • \$\begingroup\$ So, in your experience, the gate rise time looks good? I will try increasing the resistors, and let you know. Thank you! \$\endgroup\$
    – HarKal
    Commented Aug 25, 2022 at 8:34
  • \$\begingroup\$ The gate turn-off is slow. The symbol for D2 and D3 indicates a schottkey diode. Is it really a schottkey diode? \$\endgroup\$
    – Mattman944
    Commented Aug 25, 2022 at 8:36

1 Answer 1

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The MOSFETs you are driving have an input capacitance of 13 nF. The switching time characteristics of the IR2104 assume a 1 nF load. This might seriously affect rise and fall times causing excessive power dissipation in both MOSFETs. You need a stronger MOSFET driver in my opinion.

@Andyaka You are right! I swapped them out for some FQP50N06 I had laying around, and now it works like a charm! Thank you for noticing this!

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