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Topic: Uno - Vin pin or Jack connector? (Read 703 times) previous topic - next topic


I know the Uno has an on-board regulator and I was wondering where the Vin header pin is connected in relation to the jack connector.

The reason I ask is I have a shield that uses FETs to control LED strip.  This is connected to the Uno via the Vin.  If I connect the power via the jack on the Uno does the shield draw it's power straight from the jack.  Or would I be better supplying the power to the shield, which woudl then supply the power to the Uno via the Vin pin.

The only reason I ask is that the voltage reg is getting warm and I'm sure when I connect the power to the shield first it doesn't get as warm. But it would seem logical that the Vin pin is connected directly ot the on-board jack, and wouldn't go through the voltage reg anyway, so it may just be all in my head lol.


They are both connected to the same place: input of the 5V regulator.
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They are both connected to the same place: input of the 5V regulator.

Almost, the power connector positive first goes through a polarity protection series diode that will drop about .6vdc, compared to if you were coming in via the Vin pin. Also if using the power connector then the series diode will establish the maximum safe current you can have going to both the regulator and out the Vin pin (if used) combined, to a nominal 1 amp rating.


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