Ceramic capacitor question for the electronics guys

I dont know if this is the right place to ask this question but here goes.

I was reading the drv8302 spec sheet, and if i understood it correctly(Thats a big if) it recommends a 4.7uf cap of its various supply inputs.

I looked at the bom for the 4.12 vesc and the caps used are package 1206 50v 10uf UMK316BBJ106ML-T. However on its spec sheet it states at 40-50v the capacitance is -90%! so only 1uf.

I see people upgrading the caps to 1206 100v 4.7uf, for example the 12061Z475KAT2A but after looking at its spec sheet. Even they dont fair much better at -70% 40-50v so only 1.4uf…

Am i missing something? or does the capacitance not matter so much for the transients? maybe the drv spec sheet takes into account all this when recommending the 4.7uf.

Im considering either stacking 2x 1206 100v 4.7uf or 1 x 10uf 100v package 1210 package assuming the extra width will fit.

Calling @JohnnyMeduse

Deflecting it on @Blasto

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@JohnnyMeduse that’s not allowed! Your tag says DRV Wizard, I’m putting @psychotiller’s mom on you!

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I just noticed there are few in parallel on the vesc schematic :laughing: That explains it and makes sense doh. 2 x 50v and 1 x 100v, not sure why not 3 x100vs. No doubt something else i dont understand yet lol. Its all very interesting though.

Yeah… NOT CAPACITOR WIZARD… :joy::joy::joy:

@danielz but the higher rated voltage the better, but I think 1206 10uF 100V doesn’t exist :thinking:


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Maybe this is one of @chaka’s mods that help improve reliability, adding higher uf caps

Chaka mod was 4,7uF 100V and 2 X 15uF 100V, but as I experiment in a few time it is not a bullet proof upgrade.

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1210 :smiley:

I need me an oscilloscope!

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