nRF5340 PDM CLK duty cycle

[Poki Huang]

Hi 

1. At nRF5340 datasheet page 420, the PDM duty cycle is 40%~60%, any register can tune duty cycle? Or it's nRF5340 variation tolerance?

2. Since our DMIC IM69D128S duty cycle spec. is 45%~55%, we test 2 pcs PCB and find if we tune frequency, the duty cycle will change(see below pic.), can we use this way to tune duty cycle or not?

Thank you

 

Poki

[Ressa]

Hi Poki,

That's a good observation but there is no official document to guarantee that observation for all conditions. But as a general rule you would expect stable signal characteristics for lower frequencies as you observed.