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adun
Posts: 102
Joined: Fri Mar 20, 2015 9:25 am
Location: Switzerland

RPI 3B+ backpowering protection circuit

Mon Mar 19, 2018 12:51 pm

By looking at the reduced schematics of the 3B+ if saw that compared to the 3B the backpowering circuit has been removed.
Is there any reason why this was done? Is there now no “ideal diode” protection anymore?
https://raw.githubusercontent.com/raspb ... ircuit.png

klricks
Posts: 6539
Joined: Sat Jan 12, 2013 3:01 am
Location: Grants Pass, OR, USA
Contact: Website

Re: RPI 3B+ backpowering protection circuit

Wed Mar 21, 2018 3:19 am

adun wrote:
Mon Mar 19, 2018 12:51 pm
By looking at the reduced schematics of the 3B+ if saw that compared to the 3B the backpowering circuit has been removed.
Is there any reason why this was done? Is there now no “ideal diode” protection anymore?
https://raw.githubusercontent.com/raspb ... ircuit.png
I am guessing that it was removed because a reverse polarity fault at the micro USB input is very rare. Also the circuit did nothing to protect the RPi from the more likely fault where reverse polarity is applied to the 5V GPIO pins 2 & 4.

Simple cost / component reduction may be a reason as well.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

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