ADV7180 Noise Issue

We experience noise problems when DVDDIO is set to 3.3V. The 3.3V rail is generated from 5V with a voltage regulator and is used only to power DVDDIO on the ADV7180 as well as the associated external 28.63636MHz oscillator and VPUMP for the FPGA.

  • I think that the issue here is that the DVDDIO supply on the ADV7180 is connected to the 28.63636MHz oscillator. The DVDDIO supply is quite noisy and is inputting noise into the oscillator. This results in an unstable output.

    I advise using separate supplies to power the DVDDIO and ADV7180.

    Reference ADV7180 schematics can be found on the design support form page:

    http://ez.analog.com/docs/DOC-1622

    The reference schematics for each version of the ADV7180 are stored as pdf files in the Eval_Board_Docs.zip folders.