Electronic – so special in the power MOSFETS IRFD120 and IRFD110

hobbyistmosfetpower electronics

I was trying out a hobby project and I was using the IRFD120 and IRFD110 power MOSFETs to control a motor. The transistors worked pretty fine and we simply ran out of them. When I went to buy some more I found out that they are outrageously expensive for a transistor. However, I found the FQP30N06L and FQP27P06 power MOSFETs for normal cheap transistor price. This raised my "sanity" flag. I thought that I knew which parameters matter, yet it seems that there is another parameter so important that it affected the price this much price. I ran a small specs comparison and I got this (comparing N-channel only for simplicity):

  1. FQP30N06L:

    • Current Rating = 60 A
    • Voltage Rating = 30 V
  2. IRFD110:

    • Current Rating = 1 A
    • Voltage Rating = 100 V

This clearly shows that the FQP30N06L can withstand more power, yet it is ~5 times cheaper than the IRFD110. Is it only the 100 V rating that is making the IRFD110 so special?

I am asking this question because I need to buy large quantities and I haven't used the FQP30N06L yet. Would it be a good idea to replace the stock of IRFD110 and IRFD120 with FQP30N06L and FQP27P06 for hobby project related applications similar to this: youtube.com/watch?v=Y-afnY32RrY?

Best Answer

The 100V could be a reason: high voltage MOSFET tend to be quite expensive. But I think in this case, the reason is the strange package the IRFD110 uses. This is non standard and certainly uses specific production lines.

And usually, the reason is just that: they use older technology that is more expensive to produce than newer technology. The older products then become more expensive, although they are not better speced (usually, they are worse, as you have noticed for the current handling ).

Now, if you look for a replacement MOSFET, look at the datasheet

  • The voltage handling (both in VGS and VDS) should be the same or above (in your case, it's below, so double check that you can do this in your circuit)
  • The current handling should be the same or above.
  • The VGs gate threshold should be similar (in your case, it slightly below, but that is less of a problem than if it's above)
  • The RDSon should be below
  • The gate charge should be in the same range (if it's a lot more, you may have to use bigger drivers).
  • Make sure the dissipation is appropriate.

If you check all this, I think you're clear.