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Thread: SGTL5000 footprint

  1. #1
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    SGTL5000 footprint

    I want to design an audio board to incorporate my personalize inputs and minimize noise through cables, so I have some questions about the design:
    1. I found that there is in stock the SGTL5000XNLA3R2, that has QFN20 footprint, will it work well instead of the QFN32? What considerations do I need to take if I change it? For example, I won't be able to add this part (I am not really sure what it does the ADDR).
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    2. I wanted to know if the AP7313 is for 1.8V, or it is at 3.3V?
    3. Can I use C0G or NP0 capacitors in the values that it is possible? Or it won’t make a difference with the X7R?

    Thanks fot the help.

  2. #2
    Senior Member Blackaddr's Avatar
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    1. ADDR controls the I2C device address. On the Teensy Audio board it looks like it's tied to ground so that will be the same as the QFN20 part.
    2. The SGTL5000 requires 1.8V on it's VDDD pin.
    3. Only capacitors in the analog signal path, or as part of an XTAL circuit benefit from C0G/NP0. Coupling capacitors are not typically COG/NP0.

    The answers to these questions are in the datasheets for the parts you mentioned. Designing a low-noise mixed signal PCB is very technically challenging. You should have a good understanding of the requirements for each chip as specified in their datasheets before attempting mixed signal PCB design.

    Also, even large QFN parts are very difficult to solder by hand, but that 20-pin part is 3mm x 3mm. Are you paying a PCBA house for assembly?

  3. #3
    Senior Member PaulStoffregen's Avatar
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    Quote Originally Posted by JacquelineG View Post
    ... has QFN20 footprint, will it work well instead of the QFN32?
    Yes. In fact, the next batch of audio shields will use the 20 pin part, since the 32 pin version is unavailable.


    What considerations do I need to take if I change it?
    Just connect the pins with the same signal names. The bottom side pad is the only GND pin, so it must be soldered.

    I will update the web page with new photos and schematic when we get the new boards. But it's really just pin number changes and removal of the address select solder pads.


    2. I wanted to know if the AP7313 is for 1.8V, or it is at 3.3V?
    1.8V.


    3. Can I use C0G or NP0 capacitors in the values that it is possible? Or it won’t make a difference with the X7R?
    Won't many any significant difference.

    But if you're able to find C0G/NP0 capacitors (they're normally only made for lower capacitance values) and you're able to afford them (likely to be much more expensive), yes, C0G/NP0 should work fine.

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