PCB considerations - Sigma ADAU1452
I'm starting to play with the ADAU1452 eval board. While contemplating my end product, I'm curious about some of the requirements. My first question is, and I apologize if this is too freshman, is it possible to use a double sided board with the 1452 chip or is a 4 layer the only way to go? I recognize that the main pad under the chip will be necessary which I think will eat up both the top and bottom layers of a double sided board. The question in my mind is if the necessary PS decoupling caps can be placed close enough without using the sandwiched layers.
Audio Signal Processors
adau1452
pcb
SigmaDSP Audio Processors
Hi,
I have moved this question from the Processors and DSP community to the SigmaDSP Processors and SigmaStudio Development Tool community. Please continue the discussion here.
Regards,
Craig.
Thank you Craig. After I posted this I realized that it was in the general DSP category and not the specific chip category but I couldn't figure out how to move it.
And I just came across this post from last year about this topic. https://ez.analog.com/message/122222#122222
[I did some searching before posting my original question and didn't find this post; curious. ] I have not found anywhere in the data sheet where it explicitly says that a 4 layer board is necessary. The example is certainly 4 layer. I would think that the thermal needs could be satisfied by copper thickness and the potential requirement for extra layers is lead by PS bypass needs. Anyway, this seems to be the type of answer I was looking for; although not the answer I was hoping for.
Hi Warren,
Yes, unfortunately probably not the answer you were looking for. The datasheet does seem to "suggest" a ground plane is required with the strong recommendation on page 176 - in the section titled PCB Design Considerations: "A solid ground plane is a necessity for maintaining signal integrity and minimizing EMI radiation" and "Use a single ground plane in the application layout."
You might also find application note AN-772 handy, which contains some additional board design considerations for the LFCSP package
-JT
Hi,
Where I work we also prefer the simplicity of a plain double-sided PCB whenever possible. In one of our products we have "gotten away with" a double-sided board with a ADAU1701 (my post at https://ez.analog.com/message/57200#57200 relates our experience). However, trying this with the much faster ADAU1452 would be quite a risk.
You can find good advice on which critical parts need be closest to the IC at:
SigmaDSP PCB Layout Best Practices
Best regards,
Bob
Hi Warren,
Please find page 17 of the datasheet:
http://www.analog.com/static/imported-files/data_sheets/ADAU1452_1451_1450.pdf
Aside from any signal integrity and EMI issues that would come up with a 2-layer design, the power dissipation for the ADAU145x requires a minimum of 4 layers in order to provide enough copper to wick heat away from the part to maintain reliability and longevity. The more DSP you use, the more heat is generated inside the part. Please consult the User Guide for the eval board for an example of a working layout.
http://www.analog.com/static/imported-files/user_guides/EVAL-ADAU1452MINIZ_User_Guide.pdf
Regards,
Coleman
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