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PCM4222 design questions

Jared H
Prodigy 50 points
Other Parts Discussed in Thread: PCM4222, PCM4222EVM, OPA1632

I am working on a design using the PCM4222 analog to digital converter.

I have the PCM4222EVM, and I have noticed that the PCM4222 gets pretty hot. I can see that there are thermal vias on the evaluation module to help dissipate this heat. I did not see this as a suggestion in the PCM4222 datasheet. Are thermal vias like this recommended in all PCM4222 designs?

I have measured some of the voltages around the PCM4222 on the evaluation module. The voltage on VCC1 and VCC2 (Pins 4 and 9) is about 4.02V. The voltage on VREFL and VREFR (Pins 15 and 46) is about 3.78V with a master clock present, and about 3.4V without a master clock present. I know that the VREFL and VREFR pins are not to be used for external circuitry, but I just want to make sure that everything is working properly internally on the PCM4222.

I am also looking for a recommendation for a good input buffer/filter. I have read some posts that the OPA1632 that is recommended in the datasheet and used on the evaluation module is a very power hungry device. The input to the buffer/filter section of my circuit is a 2Vpp (+/- 1V) single ended signal. I am looking for a high quality Op Amp that will allow me to take full advantage of the dynamic performance that the PCM4222 is capable of. I am willing to sacrifice power and cost for performance, so if a device like the OPA1632 is the best option, then I can work with it. I am just wondering if there might be other or better options for the signal levels that I am working with.

Information on any of these questions would be appreciated.

Thanks

  • 0
    TI__Guru**** 189399 points

    Hi, Jared,

    Cool! (pun not really intended)

    How hot is the IC getting?

    The OPA1632 was the best IC to be mated to this device when it was released. Unfortunately, I don't follow the op amps that our op amp group releases (as you can imagine, we have many groups at TI).

    You might try posting a post in the op amp e2e asking about the op amp.

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 50 points

    I attached a thermocouple to the top of the PCM4222 case. The ambient air temperature of the room was about 22C. The PCM4222 on the evaluation module had a temperature of about 46C. This is with no master clock signal connected to the PCM4222. When I enable the master clock signal, the PCM4222 temperature is about 38C.