External crystal spec for i.MX27

[ko-hey]

Hi all

Could someone tell me the external crystal spec for i.MX27 ?

My customer is using i.MX27(MCIMX27MOP4A) in their custom board.

They're connecting 26MHz external crystal to XTAL26M and EXTAL26M and considering using new crystal which expanded the temperature specification.

So they checked datasheet but there are no specification except for the frequency.

Q1.

Is there any other spec for external crystal ?

Especially, they're worried about frequency-temperature characteristic.

I found a following thread but there are no description about it

https://community.nxp.com/message/308507

Ko-hey

[igorpadykov]

Hi Ko-hey

may be used specs for i.MX25 in Table 9. Recommended External Crystal Specifications

i.MX25 Datasheet (rev.10, 7/2013)

http://www.freescale.com/files/dsp/doc/data_sheet/IMX25CEC.pdf

Best regards
igor
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[ko-hey]

Hi Igor

The spec which you mentioned is for 24MHz crystal.

Can we apply to 26MHz crystal in i.MX27 ?

Furthermore, it doesn't mention about frequency-temperature characteristic.

This means that there are no specification about frequency-temperature characteristic.

Am I correct ?

Ko-hey

[igorpadykov]

Hi Ko-hey

yes this is applicable to 26MHz crystal too.

You are right that there is no specification about frequency-

temperature characteristic.

Best regards
igor

[ko-hey]

Hi Igor

Thank you for quick reply.

I understood it is applicable to 26MHz and no specification about frequency-temperature characteristic.

Let me confirm whether my understanding is correct or not.

Should we fit in range of under ± 30 ppm by sum of the frequency tolerance and frequency-temperature characteristic ?

Here is a specification which is the device that customer want to adopt.

frequency tolerance：±10ppm max. (at 25±3℃)

frequency-temperature characteristic.：±40ppm max. (-40～85℃)

According to the above spec, the worst case of the customer's device is ±50ppm.

So I think the customer's device doesn't suit for 26MHz crystal spec.

They should select another device which does not exceed the worst case of i.MX27.

Am I correct ?

Ko-hey

[igorpadykov]

Hi Ko-hey

>Should we fit in range of under ± 30 ppm by sum of the frequency tolerance and frequency-temperature characteristic ?

yes

>They should select another device which does not exceed the worst case of i.MX27.

>Am I correct ?

right

Best regards
igor

[ko-hey]

Hi Igor

Thank you for reply.

I understood.

Ko-hey