(ADV7611)Why ADV7611 output SCLK befor HDMI input?

Q1) Why ADV7611 output this frequency?

       There is a way to limit on the MCLK on our HDMI receivers: I believe, this might solve SCLK from ADV7611 issue also. Let us check and update you.

        Please refer this thread ez.analog.com/.../how-do-we-limit-the-mclk-output-frequency-on-the-hdmi-receivers

Q2) Is the frequency always constant at 9.8437 MHz?

         No,The SCLK frequency is 64 times the LR (sample clock).

Thanks,

Poornima

Hi !

We will wait your update.

Our point is when user set up ADV7611 even if their is no HDMI input, what is the value for SCLK frequency.

We want know because our customer want to reduce EMI.

So it will be useful if you can tell how to limit ADV7611 SCLK frequency but still we want to know the initial SCLK frequrncy.

Also I understood that SCLK is 64 times the LR.

Then we want to know LR sample clock initial frequency.

Anyway we will wait your advice

Best regards

Kawa

Hi !

We will wait your update.

Our point is when user set up ADV7611 even if their is no HDMI input, what is the value for SCLK frequency.

We want know because our customer want to reduce EMI.

So it will be useful if you can tell how to limit ADV7611 SCLK frequency but still we want to know the initial SCLK frequrncy.

Also I understood that SCLK is 64 times the LR.

Then we want to know LR sample clock initial frequency.

Anyway we will wait your advice

Best regards

Kawa

Hi

I do not know where the 9MHz clock rate originates from, my guess would be the audio PLL is free running and maxing out.  I'd have to research this some to figure out the exact root cause

As part of your initialization you can tri-state the audio pins until HDMI is connected and see stable audio from the source.

TRI_AUDIO 0x15[4] = 1

Hi !

Thank you for your reply.

We will wait for your reply.

We already know that we can disable by using TRI_AUDIO.

Let us know if you can give us the initial frequency.

Q1)
Why ADV7611 output this frequency?

Q2)

Is the frequency always constant at 9.8437 MHz?

Best regards

Kawa

Hi !

How is it going?

Our customer want your answer ASAP.

Best regards

Kawa

Hi,

We have verified in our evaluation board, here also we could see the same phenomena i.e frequency always constant at 9.8437 MHz.

But don't know where it originate from,As Guenter mentioned "this might be the audio Pll is free running and maxing out".

This query has already forwarded to part specialist.

Thanks,

Poornima

Hi !

Thank you for your help.

I understood.

I will wait your additional advice.

Best regards

Kawa

Hi 

How is your progress thereafter?

Best regards
Kawa

Hi,

The recommendation from the expert in this case will be "to tristate the audio pin until audio is present and have not qualified the behaviour for when the audio source is not present but the pins are not tristated as the recommendation is to tristate until there is audio"

Thanks,

Poornima

Hi 

Thank you for your reply.

I understood.

Best regards

Kawa