Power supply with reverse polarity

[Code_Monkey]

Is it safe to power a device that has requirements in the specs of 0V and +5V with a power supply that provides -5V and 0V? If not, why?

[Doctorandus_P]

It's perfectly OK.

There is no real "0V" in this world. It is just a naming convention.

Take for example a regular Li-Ion battery.  You can either define the terminals as "0V" and "+3V7" or as "-3V7" and "0V".

This is also used for putting regular power supplies in series, to generate +15V and -15V when you want to power for example opamp circuits.

But you have to be careful.
With some mains connected power supply one of the outputs is tied to the "earth" connection of the mains voltage plug.
It's also common to do this with a piece of metal on the front panel, so you can choose whether you want a floating power supply or not.

[atmfjstc]

Well, it depends. In theory, an electronic device can only see the voltage difference between its inputs, so, yes, hooking up -5V and 0V to the GND and 5V inputs respectively will work, as will hooking up any voltage sources that have a value of X and X+5 respectively with respect to some arbitrary point you deem as "0V".

However, you have to be careful if the device electrically connects to other devices (even unintentionally, like their metal cases touching). If the power supply is non-isolated, its "0V" will not be entirely arbitrary, but rather connected directly to mains neutral. Thus, your device's "ground" will be -5V versus mains neutral. If you try to connect it to some other device that is itself powered by its own non-isolated power supply, and thus with a "ground" of 0V versus mains neutral, fireworks will result.