CLKOUT less than perfect square wave

[lpcware]

Content originally posted in LPCWare by tkreyche on Fri Oct 01 18:26:18 MST 2010
I was expecting a better looking square wave from the CLKOUT pin on the LPC1114...see photo for 4 MHz output.

I'm considering using it to drive an external ADC. No problem running it through a clock buffer to clean it up, but still.

Image is from my Tectronix 2445 150 MHz analog scope.

Comments?

[lpcware]

Content originally posted in LPCWare by leon_heller on Sat Oct 02 09:29:41 MST 2010
The ringing looks like a measurement artefact. Try using a very short ground connection for the scope probe, attached to a ground close to the pin.

[lpcware]

Content originally posted in LPCWare by Luis Digital on Sat Oct 02 06:15:56 MST 2010
Thanks for the information.

[lpcware]

Content originally posted in LPCWare by Ex-Zero on Fri Oct 01 21:45:05 MST 2010
Perhaps a Schmitt-trigger like:

http://ics.nxp.com/products/lvc/datasheet/74lvc1g14.pdf

[lpcware]

Content originally posted in LPCWare by Luis Digital on Fri Oct 01 19:53:21 MST 2010

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Quote: tkreyche
I was expecting a better looking square wave from the CLKOUT pin...see photo for 4 MHz output. No problem running it through a clock buffer to clean it up, but still.

I'm considering using it to drive an external ADC.

Image is from my Tectronix 2445 150 MHz scope.

Comments?

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What is the output of another microcontroller that operates at 4 MHz and 3.3 volts?

I have the same plans, but at 50 MHz, and my ADC is 5.0 volts, so I'll need a buffer. Any recommendations about the buffer is welcome.