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Author Topic: PICkit 3 Vdd output is low... VERY low!  (Read 4782 times)

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Offline glossywhiteTopic starter

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PICkit 3 Vdd output is low... VERY low!
« on: January 24, 2011, 06:41:27 pm »
Hello! :)

Just received my PICkit 3, and the one thing that puzzles me is why, when I set PICkit 3 to power the board in "Programmer >> Settings >> Power" and then adjust to 5v and click "Apply", my DMM only measures 3.84V on the Vdd pin...

Is this normal?  ???

Thank you
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Offline TopherTheME

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Re: PICkit 3 Vdd output is low... VERY low!
« Reply #1 on: January 24, 2011, 07:04:07 pm »
How much current is your circuit drawing? The PicKit 3 can only source a couple hundred mA IIRC.
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Offline glossywhiteTopic starter

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Re: PICkit 3 Vdd output is low... VERY low!
« Reply #2 on: January 24, 2011, 07:31:19 pm »
Quote from: TopherTheME on January 24, 2011, 07:04:07 pm
How much current is your circuit drawing? The PicKit 3 can only source a couple hundred mA IIRC.

ONLY a couple of hundred, you say? LOL! It's just a 16f627 on its own, the circuit.

The demo board that comes with it is plugged in now (it wasn't before) and MPLAB says it is set to 3.25V... but it measures 2.3V on DMM...

hmmmmm
« Last Edit: January 24, 2011, 07:41:26 pm by glossywhite »
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Offline TopherTheME

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Re: PICkit 3 Vdd output is low... VERY low!
« Reply #3 on: January 24, 2011, 08:14:54 pm »
Thats strange. My PicKit 3 is dead on when it comes to voltage, down to two decimal places. Are you measuring it at or close to the pickit?
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Offline glossywhiteTopic starter

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Re: PICkit 3 Vdd output is low... VERY low!
« Reply #4 on: January 24, 2011, 09:15:38 pm »
Quote from: TopherTheME on January 24, 2011, 08:14:54 pm
Thats strange. My PicKit 3 is dead on when it comes to voltage, down to two decimal places. Are you measuring it at or close to the pickit?

It measures under-voltage at the PICkit 3 end AND the project end.
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Online Zero999

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Re: PICkit 3 Vdd output is low... VERY low!
« Reply #5 on: January 24, 2011, 09:55:49 pm »
Is anything connected to the project?

Check you've not done anything stupid such as connecting your DVM, set to measure current, across the power supply rails.
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Offline glossywhiteTopic starter

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Re: PICkit 3 Vdd output is low... VERY low!
« Reply #6 on: January 24, 2011, 10:49:11 pm »
I think my DMM probes must have been badly connected, as BOTH my PCs measured 4v coming from USB, after testing all possible permutations of USB root/hub, diff leads, testing local and remote end, etc etc. Now it comes right - 4.95v! :D
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