[TriEmbed] RaspPi Power Protection

Robert Gasiorowski rgresume at gmail.com
Fri Jan 15 13:14:38 CST 2016


You can use something simpler: MOSFET, Zener, and resistor.

https://www.maximintegrated.com/en/app-notes/index.mvp/id/5026


On Fri, Jan 15, 2016 at 2:02 PM, Adam Haile via TriEmbed <
triembed at triembed.org> wrote:

> Oh cool... I was hoping it was possible to just cut the voltage above a
> certain level.
> Thanks! I'll look further into that.
>
> On Fri, Jan 15, 2016 at 2:00 PM, Rodney Radford <ncgadgetry at gmail.com>
> wrote:
>
>> I couldn't find the MAX486C used in that schematic, but I did find other
>> chips in the MAX486 family made by Maxim.  The first few paragraphs explain
>> how the chip works, and what the P and N channel MOSFETs do (one is for
>> overvoltage to turn off the supply to the load, and other is for negative
>> voltages to turn off the incoming supply completely).
>>
>> A nice find and will work great for your need.
>>
>> On Fri, Jan 15, 2016 at 1:42 PM, Adam Haile via TriEmbed <
>> triembed at triembed.org> wrote:
>>
>>> Ahh, yeah. That little protection circuit (bottom left corner I assume)
>>> quickly gets WAY over my head. I see what chips are there but have no idea
>>> what that actually *does.* This is why I left CompE for SoftE... analog
>>> circuits fry my brain :P Will have to research those chips some more and
>>> see if my brain doesn't melt :P Thanks for the link... at least now I see
>>> how it could/should be done. And in a VERY similar application.
>>>
>>> On Fri, Jan 15, 2016 at 1:31 PM, Alex Davis via TriEmbed <
>>> triembed at triembed.org> wrote:
>>>
>>>> Check out how they did it on the Adafruit Pi Matrix Hat:
>>>>
>>>> https://learn.adafruit.com/system/assets/assets/000/022/441/original/leds_schem.png?1421437847
>>>>
>>>> It's all 5v, but the power input protection would be of interest.
>>>>
>>>> In my application, I run a 62x32 matrix off the same power supply as the
>>>> Pi2, and to keep things happy required significant bypass caps across
>>>> the power input to the matrix.
>>>>
>>>> > I'm playing with an idea for a Pi Zero "Hat" that would involve
>>>> LEDs... I
>>>> > know, shocking.
>>>> >
>>>> > So, I figured it would be possible to power the Pi off the LED power
>>>> > input
>>>> > but I want to support 12V LEDs as well. My current plan is just a
>>>> jumper
>>>> > (solderable probably) and a stern warning that it's your own fault if
>>>> you
>>>> > fry your Pi.
>>>>
>>>>
>>>>
>>>> --
>>>> "The theater of noise is proof of our potential."
>>>> |\ |  (¯  \/ |¯\  |V| |\ ¯|¯ |¯) | \/ | | | |¯\ (¯   /¯  /\ |V|
>>>> |-||_ (_  /\ |_/ @| | |-| |  | \ | /\ |^| | |_/ (_ . \_  \/ | |
>>>>
>>>> You won't find me on Facebook.
>>>>
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>>>
>>>
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>>
>
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