| Electronics > Projects, Designs, and Technical Stuff |
| Searching a high-side driver ic for a p-channel MOSFET, do you know any? |
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| Ian.M:
Try the attached high side PMOS driver circuit (LTspice sim). It gives fractionally under 7.5V of gate drive at 8V Vcc, rising to 10V at 12V Vcc, and limits the drive to 12V at 36V Vcc. If built with careful attention to layout, decoupling and parasitics, it should be brutally fast. Sub 100ns edges are possible. N.B The input must swing rail-to-rail of your logic supply. If it doesn't go below 0.2V you wont get a fast enough turnoff and any droop in its high level will result in reduced gate drive. |
| Jajaho:
Well you know what they say about celebrating to early... |O The smart switch I mentioned earlier is terribly slow. Turn on time: typ. 150µs & max. 300µs Turn off time: typ. 200µs & max. 550µs I have to switch it at up to 10kHz... Naive calculation: 1 / 850E-6 = 1176Hz, so that won't work It's back to the drawingboard. I will try your recommendation and simulate the discrete p-channel driver. The AUIRF405 should be fast enough with 99ns rise time and 64ns fall time. But since I'm planning on using a jellybean attiny to controll it all I'm pretty sure it won't do rail to rail. Do you have any suggestions on what to do about that? |
| Jajaho:
Hello Ian M., first of all thank you for your answer. But I tried running your attached .asc using LTSpice and got this instead (see attached photos). It can't find the models you used. Are they your custom ones maybe? EDIT: Never mind, the problem was on my side. I reinstalled the thing and now it shut up. |
| SiliconWizard:
Can you explain why you're not going for an NMOS transistor instead? As said above, it'll be much easier to find one with better specs than a PMOS and the gate drivers are easy to find. |
| Jajaho:
Hello Silicon Wizard, the BTS6361D is just that. A n-channel MOSFET with a driving circuit, all in one package (plus some). But since it requires a charge pump to boost the supplied voltage above the operating voltage in order to turn on the MOSFET it is much slower at it compared to a traditional driver. This is a problem since I have to modulate it using PWM up to 10kHz. In addition the AUIRF4905 is a very well performing p-channel MOSFET that can keep up with the N-channel guys. I think you could also use an isolated photo-driver of some sort and if you have a specific recommendation I am more than willing to look into it. I hope I made my reasons clear and that I'm not overlooking something. Thank you very much for your question though and please let me know what you think about it. Greetings from Germany. |
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