thank you for explanation.
The ZVD is for safety because of over- and undervoltage? or is it to be safe about mix up + and GND?
Here is quote from another site: (I use a Raspberry Pi 3B+)
NOTE that the Raspberry Pi 3B+ and Pi Zero and ZeroW do not include an input ZVD. The micro-USB input on a Pi is expected to / almost universally is driven by a power source which does not sink current, i.e. it will not try to actively pull down a voltage higher than its regulated voltage. If a HAT back-powers a Pi and uses a power source that does not try to sink current (and will safely stop/pause regulation if its input voltage is higher than its regulation voltage) it is OK to not include a ZVD on a HAT. If you are unsure or don’t know then please include the ZVD!
This means if my power input is safe with over-and undervoltage i don’t need a ZVD?
What is the meaning of this quote:
If the add-on board uses any more GPIO connector pins than the first 26 and provides back-powering via the 5V GPIO header pins it is required to:
1. Implement a duplicate power safety diode before the HAT 5V net (which then feeds power back through the 5V GPIO pins) as shown in this diagram. Alternatively provide some other mechanism to guarantee that it is safe if both the Pi PSU and add-on board PSU are connected. It is still recommended to add this circuitry for new board designs that only implement the first 26 pins of the GPIO header but that also implement back powering (see below note)
2. Make sure that the supply that does the back-powering can supply 5V at 2.5A.
Now i found out the HIFIBerry has 5V Pins. They are somehow connected to de GPIO Header. I couldn’t find a schema, just this information from HIFIBerry:
If i don’t de-solder the resistor i can use it to backpower the Raspberry?
I also read about linear power supply. Is this needed or just a bit better than my first choice of power supply?
or better this?