Post Go back to editing

ADA4075-2 and SSM2167 Q's

Hi,

We are looking at using the ADA4075-2 instead of the OP275, as recommended by ADI, as a balanced line driver to the AD1974. However, the reference design uses trimpots whereas these are not shown for the OP275 reference design. As we are looking to have 12-16 inputs per PCB, it isn't feasible to tune each individual trimpot. Can these be left out or are there standard resistor values which are used which produce 'good enough' results.

Further to this, there are in some places specifications for the ADA4075-2 and SSM2167 in the datasheets as to what type of capacitors to use, however not always. I was wondering for a general idea of what types of capacitors are suitable for these devices. I have read conflicting information about how 'bad' ceramic capacitors are in audio etc and just want to get some device specific info.

Thanks

Parents
  • Thanks for the thorough responses, they address my original questions.

    I have some final follow-up questions.

    1)  Looking at the schematics that you posted, I am unsure about a few things.

    • What is the purpose of the parallel RC filter near the input jack and how are the values derived?
    • If Vref is GND then why are the additional AC coupling capacitors required on the opamp outputs?
    • How are the AC coupling caps on the input calculated?
    • Why is the LPF (237R and 1nF) required on the opamp output?

    2) We have 3.3V on board but haven't yet selected the V+/V- supply for the ADA4075. The minimum for the ADA4075 is +/-4.5V, seeing as though the Vp-p to the AD1974 is around 2, is there any need/benefit to go above this miniumum? Also, what Vref can I use so I don't need the additional AC coupling caps on the output side of the opamp?

    Thanks

Reply
  • Thanks for the thorough responses, they address my original questions.

    I have some final follow-up questions.

    1)  Looking at the schematics that you posted, I am unsure about a few things.

    • What is the purpose of the parallel RC filter near the input jack and how are the values derived?
    • If Vref is GND then why are the additional AC coupling capacitors required on the opamp outputs?
    • How are the AC coupling caps on the input calculated?
    • Why is the LPF (237R and 1nF) required on the opamp output?

    2) We have 3.3V on board but haven't yet selected the V+/V- supply for the ADA4075. The minimum for the ADA4075 is +/-4.5V, seeing as though the Vp-p to the AD1974 is around 2, is there any need/benefit to go above this miniumum? Also, what Vref can I use so I don't need the additional AC coupling caps on the output side of the opamp?

    Thanks

Children
No Data