ricardo.santos wrote: ↑
Fri Jun 08, 2018 9:56 am
I've tested with an official rpi power supply and i get 5.19v from 5v pin. Is this normal?
I should not restrict it to 5v with something before connecting to sensors or micro-controllers
Yes, that is normal.
In fact any voltage within 5% of 5.00Volt is okay, so anything from 4.75V to 5.25V is acceptable.
Note that we are talking about the voltage ending up at the PI, and that cable losses of a tenth of a volt are common (the cable has resistance, so if there is a current running through the cable some voltage loss will occur in the cable).
That is why well designed RPI power supplies are designed to compensate for that loss, also it means that what ends up on the PI can vary slightly depending on how much current is used, so measuring on the PI isn't a static thing, and should be done with an oscilloscope.
Obviously putting too much voltage on any device is bad, but for 5V devices the absolute maximum voltage they can withstand is often something like 6.0 Volt, that is why most PI's contain a kind of Thyristor (Over-voltage-protection OVP) device that shorts out the 5V input when you put 6Volt or more on the 5V micro-USB input, this then should blow the PI's poly fuse (to in turn protect the over-voltage-protection diode from burning up).