Powering Up the Nexys 3 board using external wall plug supply

[Anind]

Hello everyone,

I built a power stabilization feedback circuit using the Nexys 3 board. For this application, I need the board to get powered up externally using a 5V DC wall supply . For this purpose, I used a coax-center positive 2.1 mm internal diameter barrel plug (as was mentioned in the page 7 of the manual which is attached along with this query). I changed the power select jumper JP1 from "USB" to "Wall" . Now I supplied power from an external 5V DC supply and as I turned on the onboard switch , the board did not power up and also, somehow, the power supply circuit got 'short' .It maybe mentioned here that there was nothing wrong in the power supply which I used for this case i.e. it was working fine prior to this .   Also on changing the power select jumper back to "USB" , the board still gets powered up via the Adept USB port. Hence, this made me believe that I might be missing something in getting the board powered up externally. Also, there is a J11 jumper in case, someone wants to power up the board using a battery . However, before going ahead with that , I thought its best to clarify things lest I might end up damaging the board. Any help on this would be appreciated. Thanks in advance for your time.

PS : The power supply I used is a home-built general purpose power supply giving +/- 24V , +/-15 V , +/- 18 V and +5V as the output. While other voltages are still good , the +5 V section got shorted out when I tried to power on the nexys 3 board. 

 

Nexys3_rm_fromDigilent.pdf

[JColvin]

Hi Anind,

Based off of your description, it sounds like you've done everything correctly. The bit that confuses me is the fact that you can still power your board just fine from USB, but not the power supply, so (in theory) the board hasn't been burnt out.

I guess the only thing I'm wondering about is the current output for your power supply; the reference manual states that the external power supply should be able to supply 5 Watts (so 1 Amp at 5V) to properly power the board. I'm guessing that your power supply can output at least one amp based on the voltage range that it has, but I figured I would double check anyway. Another random thought would be to check the the coax connector on both your power supply as well as the barrel jack connector on the Nexys 3 to make sure that there isn't any accidental short occurring between pins. 

Beyond that, I'm not certain at the moment what else could be the culprit.

Thanks,
JColvin

[Anind]

Hello JColvin,

Thank you for your reply. Yes, the board still works when I power it up using the USB. As you have suggested, I shall recheck the current output , although I am quite certain it should be able to provide 1A as I have been using the similar supplies in operating photo-detectors , amplifiers etc. At the moment, I need to re-work the 5V supply section as it has got short. Maybe, the barrel connector could be a culprit. I shall update whenever I get the thing working. It is good to know from you that I am not missing anything while using the external supply.

[Anind]

Hello,

After re-building the supply , I changed the barrel connector and the board now gets powered up . Thank you JColvin sir for your reply :-)