Single transistor constant current power led driver.

One Watt?

Yes 350 mA - 3V

You probably need a lower value resistor between 'drive' and 'base' or the transistor can't turn fully on.

Ok, I wil try. In the above example my base current is 1.6, 2, 5 mA, with a 1kOhm resistor, so I am in OutputPin safe area

Thanks for your answer