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I'm trying to design a power supply for a class D, stereo audio amplifier based on the TPA3250. I have a transformer that will give me 35V on the secondary which I plan to rectify and smooth to supply the below SMPS. Is this circuit suitable to supply 36V up to 10A and am I likely to run into problems with noise?

WEBENCH power supply

SMPS

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  • \$\begingroup\$ Do you mean the transformer gives 35VAC RMS on the secondary? \$\endgroup\$
    – John D
    Nov 27 '19 at 23:29
  • \$\begingroup\$ Correct, so I would expect to have around 50VDC post bridge rectifier/smoothing caps. \$\endgroup\$
    – Joe Mann
    Nov 27 '19 at 23:35
  • \$\begingroup\$ You may want to go through the data sheet and double check the values. The inductor and Rsns values are consistent with a 10A supply running at 500kHz (set by Rt), but the pass transistors they call out seem absurdly huge -- 80V and 200A, really? It could be that they're just trying to bring the \$\mathrm{R_{DS}}\$ down, which I guess is good. \$\endgroup\$
    – TimWescott
    Nov 28 '19 at 0:12
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Overall it seems OK. The 500kHz switching frequency should help with noise, although you can always add a second inductor/capacitor stage for further filtering. As long as you don't end up with broadband hash in the output due to noise in the regulator, and as long as it doesn't oscillate, I suspect you'll be fine.

Layout will be critical. You really need to think like an electron to keep the supply stable and to keep it from radiating.

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