I have a project where i need to power the PI via gpio/TP. After many hours searching i cant seem to find a circuit design that has already been completed. Im very familiar with designing the circuit to use a regulator from a 12v dc source to supply the +5v needed, but im not sure where/what kind/what rating of fuses(glass, fast act, poly ect) to use to make sure the pi is safe.
Does anybody know of a circuit that is circulating on the net, or have experience on what fuses and where to place in the circuit for max protection.
Thanks!
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dale-sampson
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Re: Diy Power Supply
For a resistive load like RPi the fuse could be fast acting type. For example microfuse mounted on the PCB. Main purpose of the fuse is to protect the upstream power supply however and it will cut the current in case that you have a short in power cables or connectors. Protecting RPi from bad voltages levels or polarity inversion is then a different story.
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mahjongg
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Re: Diy Power Supply
fuse must be between 1 and 2 ampere, and cause less than 0.1V drop at 1A.
Re: Diy Power Supply
As hampi said, a fuse is only to protect the power supply from faults in the cables and connectors. The Pi already has a fuse to protect itself.
So the question becomes, what fuse do you need to protect the power supply, which only you can answer because only you know the circuit. The Pi is sensitive to low voltage, so you do need to be sure the voltage drop from the fuse is not too high. A replaceable wire fuse at 1A or 2A would be fine. A self-resetting fuse at 1A may be more problematic; they have a significant voltage drop.
If you've got voltage sensing, then you could sense the voltage at the output of the fuse. Or it may be that the components you are using are already protected against short-circuits and don't need a fuse.
So the question becomes, what fuse do you need to protect the power supply, which only you can answer because only you know the circuit. The Pi is sensitive to low voltage, so you do need to be sure the voltage drop from the fuse is not too high. A replaceable wire fuse at 1A or 2A would be fine. A self-resetting fuse at 1A may be more problematic; they have a significant voltage drop.
If you've got voltage sensing, then you could sense the voltage at the output of the fuse. Or it may be that the components you are using are already protected against short-circuits and don't need a fuse.