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TPS62162: Crosstalk with TPS62163, frustrated with previous support I was given.

Part Number: TPS62162

I have been having odd problems with my two VREGs, this is related to the post I made previously. Anyways, my layout was not the problem, which was a theory I was little skeptical of given the symptoms. I assembled my new board and the problem was still present, so with that possibility gone, and the fact that I have used one of these before in a build, it had to be some sort if cross talk between the 5V reg and 3.3V regulator. So I removed the 5V regulator from the PCB and my problem with the other regulator was instantly fixed.

This was a possibility that I brought up in my previous post and it was completely ignored, and while I don't expect this support forum to be wizards when it comes to this sort of stuff, I am a little frustrated with the absolute confidence in the answer I was previously given, this is a university project, and I do not have very much time or resources. If you are not one hundred percent sure on the answer you are giving to customers, you should mention this in the reply. I ended up ordering the exact same PCB, with the same problems, because of cookie cutter advice that is given to anyone that doesn't follow their layout, which for this specific product does not exist anyways. Interference between multiple regulators is absolutely something that should have been tested, and this is definitely a bug that should be noted somewhere in both the products documentation. It should be noted in every switching regulator you sell. And threads should not be locked until a solution has been reached.

5V and 3.3V are very common, and I suspect this problem exists in some small form on every board that uses any two regulators from this family. And this may be a common problem with switching regulators that I am not aware of, but I mentioned this idea in my initial post, and it was not considered. 

This post isn't just for venting my frustration, my project is now overdue, and I am not sure specifically how these two circuits are talking to each other. I am pleading anyone with any sort of knowledge on this stuff to help me. I will not be using these regulators on my next iteration, but if somehow this issue really has nothing to do with these ICs I would really like to be made aware of this. If this was something that was actually tested in production, I would like to know. 

 

  • Hello,
    sorry for the delay due to the holidays period. We will get back to you as soon as possible in the first week of January.
  • Hi Jacob,

    Thank you for your patience while TI was on holiday these past weeks.

    Let me first clarify some expectations of the E2E community. We are not here to design your circuit. This is the customer's job. We do provide advice and recommendations for component selection, debugging, etc. (If you want the official online terms of use, this is found here: www.ti.com/.../termsofuse.shtml)

    As with any type of support/troubleshooting (for your internet connection, for your car, etc.), it is extremely rare that the solution is 100% known when the initial symptom presents itself. It almost always requires debugging, trial and error, etc. to identify the exact root cause and a solution. Based on your symptom and based on our interactions with lots of other customers, layout items are a frequency cause of many behaviors.

    If you want to do more debug on your design, let me know. I can also un-lock the older thread for you so the discussion can be continued there.

    Crosstalk is an industry-known issue that needs consideration on almost every design. It can occur between anything that has a switching signal (aggressor) and any node which is high-impedance enough (receptor). Aggressors include any switching DC/DC, I2C lines, clock signals, etc. Receptors include almost every small-signal analog circuit.

    I'm not sure if I answered all of your open questions. Just let me know if you still have some and if you want to re-open the other thread for more debugging of your issue.
  • Hi Jacob,

    Let me know if you still want to discuss any details of your project. You should be able to reply to this thread for a few weeks before it locks.