| Electronics > Projects, Designs, and Technical Stuff |
| Is this MOSFET driver circuit ok? |
| << < (4/6) > >> |
| Chriss:
I can say only big THANK YoU! The diagram shows everything. Thanks again to all of you to put me in the proper direction. My best regards. |
| langwadt:
--- Quote from: Zero999 on January 13, 2020, 07:28:11 pm --- --- Quote from: floobydust on January 12, 2020, 11:44:17 pm ---Best to look at a logic-level N-ch mosfet that is OK with 5V drive. IRF1010 needs well over 5V drive. --- End quote --- I agree it's not ideal, but it's rated for 60A and the original poster is only using it for 2A, which it can happily do, even with only 4.5V of gate drive. https://www.infineon.com/dgdl/irf1010npbf.pdf?fileId=5546d462533600a4015355da754e188b --- Quote from: Chriss on January 13, 2020, 01:21:55 pm ---Ok. I understand now the clamping... If I just replace the D1 with a fast recovery one, like someone wrote before, does that would be enough to make the proper clamping circuit? --- End quote --- If you want to turn the solenoid off as quickly as possible, then any freewheeling diode will slow it down. When the transistor switches off, the current keeps flowing through the inductor and diode. The voltage drop across the diode will be just over a volt or so, at 2A, so the current will decay very slowly. A zener diode in reverse parallel with the MOSFET will dissipate the energy more quickly than a free-wheeling diode. You need to choose a zener diode with a slightly lower breakdown voltage, than the MOSFET. --- End quote --- or depending on the rating of the FET skip the zener and let the FET do the clamping something like a VND7N04 has clamping and temperature/short circuit protection |
| Chriss:
Hmmm. This fet what mentioned the VND7N04 looks very interesting. I think I could save several parts with changing from my fet to the VND7N04. Thanks for this info. |
| DBecker:
You probably want something with a little more power handling capability so you don't have to be so careful with the gate voltage and heatsinking. The VND14NV04 is an older part that is now inexpensive. I recently bought a few on Aliexpress for 0.40 each. Note that because the fault feedback shorts the gate input, it requires a resistor in series with the gate. The gate is best driven with 5V, but it's still usable at 3.3V. |
| MagicSmoker:
--- Quote from: langwadt on January 13, 2020, 11:19:02 pm ---... or depending on the rating of the FET skip the zener and let the FET do the clamping something like a VND7N04 has clamping and temperature/short circuit protection --- End quote --- I'd advise against this as not every FET is going to be happy with being repetitively avalanched, meaning a careless replacement could result in the immediate release of the precious magic smoke. Instead, replacing the freewheeling diode with a 24-36V bidirectional TVS* is a much safer alternative that will still achieve very speedy turn-off of the solenoid yet allow almost any MOSFET to be used in the circuit (well, any MOSFET with a Vds rating >50V or so, depending on what voltage the TVS clamps at, exactly). * - e.g., SA24CA, SMAJ24CA, P6KE36CA, etc. |
| Navigation |
| Message Index |
| Next page |
| Previous page |