PCMD3180: PDM SI parameter confirmation

Could anyone have idea about similar case? Thanks a lot for help!

Hi Shing,

The specification mentioned is the switching characteristics for PDMCLK output that is given by the device?

I understand that your application uses a PDMCLK frequency of 3.072MHz. Are you trying to provide this clock from an external source?

Thanks and Regards,

Lakshmi Narasimhan

Hello Lakshmi,

Thanks for your replay!

Yes, the PDM CLK which is 3.072M in my use case is given by PCMM3180 ouput. Due to we add some FB/RES on PDMCLK to solve EMC issue, and the rise/fall time(25/30ns) can't meet the spec(18ns) shown on datasheet. So I want to know whether the CLK R/F time is ok in my use case(3.072M). The measurement shown as below.

BR

Shing

Hi Shing,

Couple of things that need to be checked:

1) The PDMCLK will be interfacing with an on-board digital microphone, does that microphone have any requirements for the PDMCLK rise/fall times?

2) The PCMD3180 has a timing requirement for PDM data input (setup/hold time), which can be impacted by this increase in the PDMCLK rise/fall time.

Thanks and Regards,

Lakshmi Narasimhan

Hi Lakshmi,

①. There are no requirments for PDMCLK R/F time on DMIC datasheet.

②. Yes, have checked that the SI timing setup/hold time can meet the datasheet SPEC.

So， the PDM R/F time near PCMD3180 chip side is not cirtical requirement, right? Once SI timing set/hold time can meet SPEC.

Or the SPEC(18ns) requirement is only applicable for CLK FRE 6.144MHZ?

Thansks for your help.

OK, thanks for your confirmation.