UNO Voltage question.

I have a genuine UNO and Looking at the specs which say:

Input Voltage (recommended) 7-12V Input Voltage (limit) 6-20V

I want to run a project from a 15 Volt switch mode power supply (which I already have) because the other parts of the circuit use 5 to 12 Volts using linear voltage regulators, LM7805, 7809 and 7812. The current of the supply is 6.5 Amps which is easily enough for what I nead.

As the recommended voltage is 12 Volts, does the UNO act any differently with a higher voltage between 12 and the 20 volts limit.

Am I likely to have any problems running a project with a 15 Volt supply in to the barrel connector.

Any thoughts or comments appreciated.

Am I likely to have any problems running a project with a 15 Volt supply in to the barrel connector.

Using higher voltages at Vin results in lower current available at the Uno's 5V pin(s). I'm not sure what the maximum current available before thermal overload of the 5V regulator kicks in, but with Vin=15V, it might be around 50-100mA.

This thread has a discussion of regulator input voltage versus available current, Uno regulator power

Thanks dlloyd. Thats really helpful.

Forgot to mention the supply has 2 x 15 volt outputs, so I was going to use 1 for the UNO and one for the rest of the circuits without having to change anything. I might just step down one of them to 5 volts instead for the UNO and use the other as it is for the rest.

Thanks again.

Stuart.

Thanks groundfungus, will have a read of that.

Another option may be to power the Arduino's 5v pin from the output of a 7805 - but I would dedicate one 7805 for the Arduino only. If the smoke escapes from the 7805 it won't cost too much.

...R