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Strange noise on TVP5151 [Video Added]

Morteza Zafari
Prodigy 50 points
Other Parts Discussed in Thread: TVP5151, TVP5146

Hi,

We have designed a custom board using TVP5151.

Video input is fed to TVP5151 and then to an FPGA.

There is a moving horizontal noise present on the video.

But the strange point is that as soon as I touch and release one of the pins of the 27MHz crystal with a pair of tweezers, the noise disappears and does not return!

What can be the reason? Any suggestions?

The noise can be seen below: (2 consecutive Frames)

It looks like the famous ground loop noise.

2 consecutive frames after touching the pin of the crystal:



  • 0
    Prodigy 50 points

    I added a short video of the noise pattern. 

    It is the so called barrel noise if I am not wrong.

    Any idea where the noise comes from?

    I have inspected the crystal and chosen the capacitors based on the CL of the crystal. 

    I have also changed the crystal with a 1.8v Oscillator, but still this noise is there.

    It is getting a little on the nerves. I have already used TVP5146 and the quality was really good.

    Any idea will be appreciated!

    Thanks

    Morteza

  • 0 in reply to Morteza Zafari
    TI__Mastermind 43875 points

    Make sure your power supplies are filtered and clean.

    Make sure pin INTREQ has a pull up/down resistor on it.

    BR,

    Steve