PCM6240-Q1: td(SDOUT-BCLK), td(SDOUT-FSYNC) spec BCLK frequency condition

Hello Shinji,

This really depends on the standard of which you are measuring it from, like are you measuring from mid-fall to mid-rise or where each crosses a certain logic level threshold?

For a 2ns discrepancy I would need to see recording/picture of measurement to see how it is being measured.

Best,

Carson

Hi Carson,

Could you confirm if the parameter below is based on BCLK=24.576MHz or does it also applicable for all the possible BCLK frequency?

I will double check the scope shot.

regards,

It is applicable to all frequencies

Hi Carson,

Please see below captured image. 

both td(sdout-bclk) and td(sdout-fsync) violate the 14ns minimum delay time. 

Could you double check if 14ns is applicable over the operating frequency range?

regards,

Hi Carson,

In the datasheet, IOVDD=1.8V, td(sdout-bclk)=18ns, while IOVDD=3.3V, td(sdout-bclk)=14ns.

It seems lower the IOVDD, longer the delay, so I don't think high IOVDD causing this, is it?

regards,

Hello,

That correlation does not mean much because they are completely different power modes which will have other factors that affect timing, so you cannot just rule out that based those numbers. It is not like I could make IOVDD = 2.5 volts and expect a 16ns delay.  Could you adjust system temporarily to 3.3V and measure delay time then for comparison to spec.

Best Regards,

Carson

Hi Carson,

Here is the closer look at the 3.3V rail. It is 3.305V which is close to the typical value in the datasheet. 

Could you advise if there is any other possible reason of this mismatch?

regards,

Hello,

So you are using 3.3V rail?

Just looking at min and max value of previous screenshots it seemed that your rail was higher? Are your clks/data this consistently noisy/ripply?

Best Regards,

Carson

Hi Carson,

The resolution of the 3.3V rail in the initial picture was not good. Actually the supply is stable 3.3V as you can see on above data. 

regards,

Hi Shinji,

I see we take this through email so I close this now.