PLL or IMO?

Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

cross mob
Anonymous
Not applicable

 Hi folks,

   

which is better and why? A 3Mhz from PLL or 3Mhz  from IMO?

0 Likes
1 Solution
lock attach
Attachments are accessible only for community members.
ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

A summary of PSOC III clocking, attached.

   

 

   

Regards, Dana.

View solution in original post

0 Likes
5 Replies
HeLi_263931
Level 8
Level 8
100 solutions authored 50 solutions authored 25 solutions authored

The PLL cannot generate a frequency on its own. So the question to this answer might be 'only the IMO can be used as generator'.

   

The PLL might introduce a small jitter to the generated clock, but I doubt it will be noticeable for normal uses.

Anonymous
Not applicable

For those interested, IMO stands for Internal Main Oscillator.

0 Likes
ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

This might assist -

   

 

   

http://www.cypress.com/documentation/application-notes/an60631-psoc-3-and-psoc-5lp-clocking-resource...    AN60631 - PSoC® 3 and PSoC 5LP Clocking Resources

   

 

   

Regards, Dana.

Anonymous
Not applicable

Hi,

   

Note that PLL can output only above > 24 MHz. 

   

As Dana pointed out, AN60631  describes all clock sources. IMO provides only few frequencies, they are 3 MHz, 6 MHz, 12 MHz, 24 MHz, 48 MHz, 62 MHz and 74 MHz. While PLL can generated ratio multile of it's souce clock. PLL can provide you clock between 24 MHz to 80 MHz. 

   

You can also note below statement from AN60631.

   

"The PLL introduces no frequency inaccuracy, and consumes less power at a given output frequency than the IMO. Thus, when a clock is desired within the operational range of the PLL, it is recommended that the IMO be run at the minimum speed of 3 MHz, and the PLL be used to generate the desired output frequency. The resulting PLL output clock will be within the accuracy specification percentages of the input clock"

0 Likes
lock attach
Attachments are accessible only for community members.
ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

A summary of PSOC III clocking, attached.

   

 

   

Regards, Dana.

0 Likes