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OPA1632: Proper way to tie source and OPA1632 grounds?

Supira Medical
Prodigy 230 points
Part Number: OPA1632
Other Parts Discussed in Thread: TPA3251, , TPA3251EVM, TPA3255, TPA3250

Tool/software:

Hi,

I have a question regarding the correct way to tie the grounds of the source input and the OPA1632 front end as shown in the Audio-OPA1632EVM. The related power amplifier in my application is the TPA3251 and its EVM. This is specific to single-ended inputs using the RCA jacks.

In the TPA3251EVM, the source grounds (RCA jacks) are AGND1 and AGND2. These are net-tied to the TPA3251 ground pins adjacent to AVDD.

The Audio-OPA1632EVM says that C17 must be connected to source ground. How does one accomplish a ground connection between the source ground and OPA1632 ground? Is there a recommended net-tie scheme?

Secondarily, I’d like to confirm that C17 indeed stays in the circuit and it’s not R12 that gets connected to source ground.

Thanks for your assistance.

  • 0
    TI__Genius 17156 points

    Hello Supira Medical,

    Please allow me some time this week to review the EVMs and provide you a definite answer.

    Thank you for reaching out for technical support.

    Best,

    Alec

  • 0 in reply to Alec Saebeler
    Prodigy 230 points

    Hi Alec,

    Thanks for looking into this. Grounding can be tricky!

    FYI - I took a look at the EVM's for the TPA3250 and TPA3255 and interestingly, neither of these designs bothers with separate analog grounds the way the TPA3251 does. Curious, indeed.

    Regarding my second question about the capacitor (C17), I think it does stay in the circuit, as shown in Figure 5 of SLOA072.