You can't "GIVE" current to a circuit, you can only apply a voltage to it and the circuit will get the amount of current it needs as long as your power supply is able to provide it.
So for a device with a rating of 5v/0.5A you need a power supply that can provide at least 0.5A,
even if it the power supply is a 5v/5A when you connect the load with a rating of 5v/0.5A it will still draw only 0.5A.
The circuit will only draw more current if a wrong voltage is applied that is above the actual device rating and
even in that case it depends on the device kind, if it has any internal regulation or protection etc.
You can't force more current into device unless you provide more voltage to it (above rated voltage for the device) and this is something that you should avoid.
Alex