topic Re: the PLL error of the s32k312 in ppm in S32K

the PLL error of the s32k312 in ppm

dongyong1 — Wed, 23 Aug 2023 15:17:29 GMT

Dear NXP Engineers

I would like to know what is the PLL error of the s32k312 in ppm

Re: the PLL error of the s32k312 in ppm

VaneB — Wed, 23 Aug 2023 21:07:16 GMT

Hi @dongyong1

Sorry for the inconvenience this may cause.

All information related to the PLL jitter is provided in Table 41 of the S32K3xx Data Sheet, Rev. 8.

B.R.

VaneB

Re: the PLL error of the s32k312 in ppm

dongyong1 — Thu, 24 Aug 2023 01:49:42 GMT

Hi VaneB

take the last line of Table41 as an example(1680ps 120Mhz). Is it possible to calculate like this: 1/120MHZ=8.3ns, 1680ps/8.3ns=0.2. (0.2/120M)*1000000=0.002ppm

Re: the PLL error of the s32k312 in ppm

dongyong1 — Fri, 25 Aug 2023 09:18:00 GMT

Hi @VaneB

Is that right?

Re: the PLL error of the s32k312 in ppm

VaneB — Mon, 28 Aug 2023 18:42:28 GMT

Hi @dongyong1

These two specs are about entirely different things. So, I think converting the ps to ppm is not possible.

Frequency is the number of cycles executed per second. Otherwise, the jitter is about the variance of the clock period. So, if your clock period varies randomly by 10ns RMS (for example), but the period is still 1µs on average, then you can have a very accurate (but jittery) 1MHz clock.