How does this Raspberry Pi power circuit work?

Asked Oct 09 '21 at 11:45

Active Oct 09 '21 at 12:01

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I looking at the Raspberry Pi schematic (Rev 3b) and found this interesting section:

The black box is described as a diode. My understanding is that this block should perform as a diode with near zero forward voltage, but I don't fully understand how it works and what to call it.

edited Oct 09 '21 at 12:01

JRE

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asked Oct 09 '21 at 11:45

M lab

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Does this answer your question? Understanding an 'ideal' diode made from a p-channel MOSFET and PNP transistors Additional analysis here. – Dave Tweed Oct 09 '21 at 12:52
I was just going to write an answer, thanks for the link. This is basically a reverse-polarity protection. – PMF Oct 09 '21 at 12:57
@DaveTweed Yes, I think about ideal diode before but mostly, it use opamp. – M lab Oct 09 '21 at 13:30
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@PMF: No, it isn't about polarity protection at all. It's about blocking an external power supply connected on the right from back-driving the USB power, while having minimal forward voltage drop when using USB power. – Dave Tweed Oct 09 '21 at 14:25
it would probably also provide reverse polarity protection up-to 5V but that's not its design purpose. – Jasen Слава Україні Oct 10 '21 at 06:02

How does this Raspberry Pi power circuit work?

0 Answers0