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Regular Visitor
Posts: 5
Registered: ‎12-06-2014

ARTY board, external 12V power does't work

I bought a ARTY from a agent and meet one problem.

ARTY works well when powerd by USB port(J10, J13 set to USB).

But it can not power on when I plugined a 12V adaptor into J12(J10 not connect, J13 set to REF).

I tested some voltages on around the IC12 with the 12V adaptor plugined in, and took some photos, see attachments.

Any seggestions ?

Avnet Employee (Regular Contributor)
Posts: 41
Registered: ‎08-01-2012

Re: ARTY board, external 12V power does't work

Taking a look at this, can you check to see that the enable voltage on R245 is around 2.2V?  There is a voltage divider between 12V and GND on this signal, I want to make sure it's enabled.  I don't have a DC 12V wall supply, so I'm connecting my 12V bench supply through the J7 header which has Vin tied to pin 8.  My board seems to be working correctly.  The 5V should come up regardless of the J13 jumper position, but if it isn't connected to the right setting the rest of the board won't power up.

You say it does work properly from the USB port?

Thanks

Chris

Regular Visitor
Posts: 5
Registered: ‎12-06-2014

Re: ARTY board, external 12V power does't work

Sorry for replying late.

The voltage around R245 is 12V. And ARTY works good when powerd by USB port( J13 set to USB).

My ARTY  is a new one, maybe the IC12 damaged?

Thanks.

Avnet Employee (Regular Contributor)
Posts: 41
Registered: ‎08-01-2012

Re: ARTY board, external 12V power does't work

Nothing is jumping out at me to be an obvious cause for what you are seeing.  Typically if the IC were blown I would expect either a short from Vin to Vout or from Vout to GND, or an output voltage regulating to some improper level.  It seems like the IC is not turning on.

Can you check the other side of R245?  I'm curious to see what the voltage at the divider is.  It should be about 2.2V which should be turning on the part.  The enable threshold for that part is 1.2V so if it's above that I'm not sure why it isn't turning on.

Do you have an oscilloscope?  If you do I'd be curious to see if the SW output is turning on or pulsing at all.
Thanks

Chris

Regular Visitor
Posts: 5
Registered: ‎12-06-2014

Re: ARTY board, external 12V power does't work

I got just a Fluke multimeter, no oscilloscope. As the ARTY is working good by the USB port, I am still happy to use it. When I got a oscilloscope, I will reply to you. 

Thanks for your replying.