Can I use CLKOUT1/2 as clk source for other devices?

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Can I use CLKOUT1/2 as clk source for other devices?

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Takashi_Kashiwagi
Senior Contributor I

Hi Community.

We are developing a product using the IMX8MM.

According to the RM, CLKOUT1/2 pin can output a pll_clk for "TEST".

I want to use the output of this pin as a clock source for other devices.

Is there any usage restriction on this pin? 

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Best Regards,

T.Kashiwagi

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mrudangshelat1
Senior Contributor II

Hi Takashi,

The CLKOUT outputs are intended for use in validation of certain internal freq - to check register programming during bring-up and development.

Jitter and output amplitude is not guaranteed for the CLKOUTx outputs (no spec in the datasheet for either).

If jitter is not a concern, it may be OK to use CLKOUT to drive an external part. You need to check the output signal amplitude to make sure CLKOUT is able to drive the external load adequately. If the freq is too high and/or load too heavy, a signal might be attenuated too much to use. Again, there are no guarantees.

Regards,

Mrudang

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1,095件の閲覧回数
mrudangshelat1
Senior Contributor II

Hi Takashi,

The CLKOUT outputs are intended for use in validation of certain internal freq - to check register programming during bring-up and development.

Jitter and output amplitude is not guaranteed for the CLKOUTx outputs (no spec in the datasheet for either).

If jitter is not a concern, it may be OK to use CLKOUT to drive an external part. You need to check the output signal amplitude to make sure CLKOUT is able to drive the external load adequately. If the freq is too high and/or load too heavy, a signal might be attenuated too much to use. Again, there are no guarantees.

Regards,

Mrudang

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Takashi_Kashiwagi
Senior Contributor I

Hi Mrudang-san

Thank you for reply!

If the freq is too high and/or load too heavy, a signal might be attenuated too much to use. Again, there are no guarantees.

 I understand. I will talk with our circuit designer.

Best Regards,

T.Kashiwagi

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1,094件の閲覧回数
mrudangshelat1
Senior Contributor II

Hi Takashi,

The CLKOUT outputs are intended for use in validation of certain internal freq - to check register programming during bring-up and development.

Rregards,

Mrudang