LP051 excess current, warm, not detected by programmer

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bdgr
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Hello

I am building a project based on another, working one (just a new, smaller PCB basically).

I assembled the prototype, but I notice over 200mA is drawn when power is applied, and the LP051 gets warm - I am afraid I have probably damaged the IC.

Kitprog doesn't detect the LP051. Cannot acquire port.

Before I replace the IC, I need to find the problem. I have removed almost every other part from the board, and the problem remains, so I must have missed something in the schematic.

I thought it was odd that the original schematic had the NC pins connected to GND, but I left that in since it worked. Could this be the problem and I've interpreted something wrong?

Here is what's left of the schematic after removing parts.

Capture.PNG

Note that the LED glows at a different brightness most times power is applied.

On a side note, that 5-pin header is suitable for programming the blank chip via KitProg USB included with CY8KIT059 ?

Thanks!

JD

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1 Solution
DheerajK_81
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Hello @bdgr ,

The analog system power voltage, applied to VDDA relative to VSSA, can be as high as 5.5 V (absolute maximum), and must be greater than or equal to all other applied power voltages. That is, the voltage applied to the other VDDX power pins, relative to VSSD, must be ≤ VDDA. More information can be found in the PSoC5 Hardware Design Guide

In your schematic, you have set VDDA to GND. It should be going to a 5V supply with 1uF and 0.1uF decoupling capacitors to reduce noise. 

This is probably why it is getting warm. Please make this change and let us know if it works 🙂

Regards,
Dheeraj

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DheerajK_81
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First comment on KBA First comment on blog 5 questions asked

Hello @bdgr ,

The analog system power voltage, applied to VDDA relative to VSSA, can be as high as 5.5 V (absolute maximum), and must be greater than or equal to all other applied power voltages. That is, the voltage applied to the other VDDX power pins, relative to VSSD, must be ≤ VDDA. More information can be found in the PSoC5 Hardware Design Guide

In your schematic, you have set VDDA to GND. It should be going to a 5V supply with 1uF and 0.1uF decoupling capacitors to reduce noise. 

This is probably why it is getting warm. Please make this change and let us know if it works 🙂

Regards,
Dheeraj

Thanks! I missed that in the old schematic I was recapturing.

After bodging that wire on, it no longer draws excess current, and PSoC Programmer succeeds in programming it.

Although after programming, it says "Doing Checksum" and doesn't present an error, yet if I do a verify, it always fails with 2 bad blocks, first failed block at 444. Is there a 'gotcha' I'm missing here, or is the chip damaged? I will be producing a new board either way.

Thanks!

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DheerajK_81
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Hello @bdgr ,

Glad to hear that the current issue is resolved.

Do you have Verification option set to "On" under Programming Parameters during programming via PSoC Programmer? If so, then during programming, it should do the verification and throw an error in case the checksum fails. 

You can try to verify this yourself as well by using the Read to Hex feature and then comparing it with the hex file you are trying to program with. If there is a difference, there's a good chance your device is damaged. 

Regards,
Dheeraj


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When I program, it says the verification succeeds.

When I manually verify, it always fails at block 444 with 2 bad blocks. Must be a bad setting?

Yet the device works perfectly from my testing so far.

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DheerajK_81
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First comment on KBA First comment on blog 5 questions asked

I believe your firmware might be writing into the flash causing the checksum of the device and the chosen hex file to mismatch because of the changed flash blocks. Is this the case? 

Looking forward to your reply. 

Regards,
Dheeraj

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