LPC11C12 External Clock on XTALIN

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LPC11C12 External Clock on XTALIN

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I want to use an external clock source (a 12MHz TCXO) fed into the XTALIN pin of the LPC11C12 microcontroller. This could either be as a clipped sine wave (0.8V peak to peak, no negative swing) directly from the TCXO, or I could put it through a schmitt trigger to get a digital input at whatever voltage level. I read in the datasheet that to do this I should put the XTALIN pin into bypass mode (pg 29 of user manual) to allow this, but there is no mention of required voltage level/duty cycle/digital or sine input etc.

The user manual only says (at multiple points) with relation to the XTALIN pin  - "Input to the oscillator circuit and internal clock generator circuits. Input voltage must not exceed 1.8 V.", but nothing else.

Could anyone help me with this?

Thanks

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NXP TechSupport
NXP TechSupport

Hi Jeremy Leaf ,

Thank you for your interest in NXP Semiconductor products and 
for the opportunity to serve you.
Please checking the 11.2 XTAL input section in the attachment, I think it's very helpful.
LPC11Cxx datasheet:

Have a great day,
TIC

 

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NXP TechSupport
NXP TechSupport

Hi Jeremy Leaf ,

Thank you for your interest in NXP Semiconductor products and 
for the opportunity to serve you.
Please checking the 11.2 XTAL input section in the attachment, I think it's very helpful.
LPC11Cxx datasheet:

Have a great day,
TIC

 

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

View solution in original post

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