• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 45 subscribers
  • Views 567 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Question on OPA357AIDBVT power

Anonymous
Anonymous
Guru 17045 points
Other Parts Discussed in Thread: OPA357

Hi All,

 

I would like to ask a question on OPA357AIDBVT power.

 

What is the proper power supply for OPA357AIDBVT?

 

 

 

 

The upper of the following images is from SpectrumDigital’s DaVinci EVM which uses three OPA357AIDBVRG4 for its video output, while the lower is another EVM that uses three OPA357AIDBVT.

 

The question is on how should power supply be filtered? In addition to the components found in the lower image, SpectrumDigital’s schematic still has:

C255

0.01uF

L16

BLM41P750SPT

In total it has two  BLM41P750SPT now

C64

220uF

Why so large?

 

Why are these components used? Do these additional components contribute to better output video quality? Which EVM is correct?

 

And does

1.    OPA357AIDBVRG4

2.    OPA357AIDBVT

Require different power connection style, which caused the difference above?

 

I would like to have some recommendation on this DAC power connection. Could anyone provide any schematic or PCB file here?

 

  

 

 

Thanks,

Zheng

  • 0
    Guru 21975 points

    Zheng,

    Your questions seem to be related more to the specifics of the DaVinci EVM circuit board rather than the OPA357 op amp. The designer of the EVM circuit board may have been solving particular noise or interaction issues on this particular design. The large bypass capacitor used may well be more than is truly required in the application. Most common uses of the OPA357 would not require such a large value. Recommendations in the OPA357 data sheet should be adequate in most circumstances.

    You may wish to direct similar questions to the DaVinci support group as they may know of specific issues related to this EVM circuit board design.

    Regards, Bruce.

  • Anonymous
    0 Anonymous in reply to Bruce Trump
    Guru 17045 points

    Dear Bruce,

    I will try to read some theory first.

    Zheng