LPC11C12 External Clock on XTALIN

jeremyleaf — Mon, 13 Nov 2017 10:17:05 GMT

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

Re: LPC11C12 External Clock on XTALIN

jeremyzhou — Wed, 15 Nov 2017 03:32:04 GMT

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:

https://www.nxp.com/docs/en/data-sheet/LPC11CX2_CX4.pdf 

Have a great day,
TIC
 
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LPC MicrocontrollersのトピックRe: LPC11C12 External Clock on XTALIN

LPC11C12 External Clock on XTALIN

Re: LPC11C12 External Clock on XTALIN