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PSoC 5, 3 & 1 MCU

Anonymous
Not applicable

Hi All,

   

Not sure where to post this, but hoping someone can give me some pointers on bring up a custom PCB using the PSoC 5LP chip.

   

I created a breadboard prototype using: 

   

http://www.cypress.com/documentation/development-kitsboards/cy8ckit-059-psoc-5lp-prototyping-kit

   

The design worked great, following the design for this board I used Altium Designer to create a small PCB board.

   

What I am seeing now is when I apply 5V to the board the power supply hits the current limiter at 3Amps.  My first thought was a short in the design somewhere but doing a continuity check only shows 800ohms between VCC and Ground. (So it should not be drawing 3 Amps. I'm wondering if the PSoC chip is actively shorting VCC and Gnd after it is powered on.)

   

Note, all voltages for the PSoC 5LP chip are connected to the 5V input.

   

I've removed everything except capacitors and resistors from the board.  

   

Any ideas?

   

One option would be to use a small addon board to the design that only has the PSoC 5LP chip and supporting caps.  I need something smaller than the prototyping kit mentioned above, but if one is available please send  a link. (Something about the size of a quarter dollar coin with about 5-10 output lines would be ideal.)

   

thanks much for your time reading this and any information.

   

Bob

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1 Solution
Anonymous
Not applicable

thanks again,

   

Bob

View solution in original post

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9 Replies
Bob_Marlowe
Expert II

Welcome in the forum, Bob.

   

We recently had a similar case here (have a look at this thread) and it turned out that some of the power lines weren't supported correctly. Can you provide us with your schematic and, when you have got, some additional infos as layout etc?

   

 

   

Bob II (Marlowe)

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Anonymous
Not applicable

Hi Bob,

   

To save time (since we are in different parts of the world), I'm attaching the pdf.  If you answering my question helps the rest of the community avoid creating a faulty PCB then at least good came from this. : )

   

BTW, ideally making a modification to the PCB (via cutting a trace or adding a jumper) fixes the problem then that would be the best way to go.

   

thanks again,

   

Bob

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Anonymous
Not applicable

Hi Bob,

   

Is there an e-mail address I can send the PDF of the design to?

   

My e-mail address is rshankle at  sparrow-labs dot com   if you want to send e-mail there and I will reply.

   

thanks again for the help.

   

Bob

   

ps All voltages for the chip are connected to VCC which is at 5V, I don't think that is my problem but wanted to mention it.  Also if I power up with the reset button down it draws about .25 amps then after about 1 second it goes up to 3A.  (Even with reset still down.)

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Bob_Marlowe
Expert II

Datasheet for PSoC5 family states on Page 26:
You can power the device in internally regulated mode, where the voltage applied to the VDDx pins is as high as 5.5 V, and the internal regulators provide the core voltages.
In this mode, do not apply power to the VCCx pins, and do not tie the VDDx pins to the VCCx pins.

   

 

   

Bob

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Anonymous
Not applicable

Bob,

   

Thanks for the feedback.  1st do you think this could cause the problem I am seeing? (3A at 5v?)

   

2nd, see attached for reference (page 2.) Are you saying to leave VCCA and P_VCCD  floating?  (Am I missing any to leave floating?)

   

thanks again,

   

Bob

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Anonymous
Not applicable

FYI, I cut the traces to the following pins: 42, 57 and 26.  (VCCD, VCCA, VCCD) and the drawing of the 3A at 5V went away.

   

Greatly appreciate the help.  Just one last question, what is the ramification of those 3 lines floating?

   

thanks,

   

Bob

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Bob_Marlowe
Expert II

These lines should not be left floating, but buffered with a 1µF.

   

I doubt that the chip is still alive, 3A would probably kill the internal regulators.

   

 

   

Bob

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Anonymous
Not applicable

thanks again,

   

Bob

View solution in original post

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Anonymous
Not applicable

Bob Marlowe can you take a look at a similar post:  http://www.cypress.com/forum/psoc-5-known-problems-and-solutions/custom-board-bringup-cy8c5888lti-lp...

   

 

   

thanks,

   

Bob

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