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Power through vIn pin?


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#1 Rod Lopez

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Posted 10 May 2011 - 08:34 AM

Can I power the Netduino using unregulated 7.5-12 volts though the vIn pin in the board? as in... instead of using the power connector If so.. what's the maximum power I can drain? (I have a few 3.3 and 5v devices connected to the Netduino)

#2 Mario Vernari

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Posted 10 May 2011 - 08:47 AM

According to the schematic, you can. What kind of power are you meaning? The Vin itself or the regulated 5 and/or 3.3V? Cheers
Biggest fault of Netduino? It runs by electricity.

#3 Rod Lopez

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Posted 10 May 2011 - 08:59 AM

I mean the Vin, I would hope not to toast the pin or its connections, right now I am peaking at around 150mA when all servo and display hell breaks loose :) So what I would like to know is if 300mA would be okay to take through the Vin.

#4 Stefan

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Posted 10 May 2011 - 09:04 AM

I connected a 9V battery and another 12V source to Vin without any problems. It's directly connected to the power socket on the netduino.
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#5 CW2

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Posted 10 May 2011 - 10:17 AM

So what I would like to know is if 300mA would be okay to take through the Vin.

Yep, the on-board regulators can handle up to 800 mA, then it depends on the power supply you are using.

#6 Mario Vernari

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Posted 10 May 2011 - 11:39 AM

CW2 is right: if you are pulling energy from the regulated +5V (or +3.3V), then you have a limit. That limit is overall thermal: maybe you may pull even more than 800mA by using a low voltage supply as Vin. Probably you may exceed a little for peaks. If you mean to power the board with an external supply, then pull out (unregulated) power from the Vin pin, I think you may reach even 2A or so. Cheers
Biggest fault of Netduino? It runs by electricity.

#7 Rod Lopez

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Posted 10 May 2011 - 01:03 PM

I'll use Vin as input then, there's one tiny detail left though... the switching between Vin and USB for power, is it mechanical or electronic?

#8 Mario Vernari

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Posted 10 May 2011 - 01:08 PM

It's an electronic switch: as the Vin goes live, a mosfet opens the USB power circuit. Refers to the schematic, upper-left corner, U1 and Q4... Cheers
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#9 Rod Lopez

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Posted 10 May 2011 - 01:14 PM

so I thought, my EE skills are a tad rusty, so didn't want to risk it :) Thanks!

#10 CW2

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Posted 10 May 2011 - 01:18 PM

the switching between Vin and USB for power

Please note in case of USB power Netduino is configured to draw max. 280 mA (but again it depends on the hub).

Edit: To be precise, Netduino reports max. power consumption of 280 mA in the USB configuration descriptor.

Edited by CW2, 10 May 2011 - 01:22 PM.





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