Hi, I'm trying to build a half-bridge (for now) class D amp using a TC4428 gate driver. When I attempt to listen to sound I get a quiet grainy output and my power supply says I'm pulling 1 Amp so I usually quickly turn it off to not burn up any of my chips. I'm using a TL0841N op amp for the triangle wave generator, a LM393 as a comparative chip, and two n-mos'. I've tried one n-mos and a p-mos but it's much quieter and I think a nosier signal. Do you guys have any idea why my gate driver could be pulling an amp? If you have any more questions about my setup I can tell you. Thanks in advance! 🙂
Yes - that gate driver does NOT contain level-shifting circuitry (as, say an IR2110 does), so what i'm quite sure is happening, is that your low-side NMOS is stuck open, the high-side NMOS is stuck closed. The current that your PSU says is being drawn, is likely going ground -> load -> low-side NMOS -> negative rail.
NMOS's need their gate-drive voltage, relative to their source pin 🙂
http://www.irf.com/technical-info/appnotes/an-978.pdf
NMOS's need their gate-drive voltage, relative to their source pin 🙂
http://www.irf.com/technical-info/appnotes/an-978.pdf
Hmm, we also thought that one might be stuck always on but when we left it running for about 10 seconds neither mosfet got even warm (without heatsinks). Wouldn't the mosfet that was stuck on heat up?
Probably not as much as you'd think - you DO still have the load in series with the low-side FET (whose on-resistance is mere milliohms), which limits the possible current.
Is there a way to still use the TC4428 and have it work/have the mosfets switch properly? Its the only gate driver we have : /
If anything, you'll be better off putting together a discrete gate drive circuit, for example like the one from the UM10155 from Philips / NXP.
http://www.nxp.com/documents/user_manual/UM10155.pdf
http://www.nxp.com/documents/user_manual/UM10155.pdf
I have some drivers I would be willing to donate if you can use them...
8pcs MAX15012A
6pcs IRS20957S
50pcs UCC27200
I might have some really nice 150V TO-220 N-fets somewhere too, I'll have to look.
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