lpcware

Necessity for external crystal?

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by cdoerr on Fri Mar 07 01:04:55 MST 2014
Hello,

For other microcontroller lines it is often recommended or even required to use an external oscillator for anything high-speed with precise times, such as SPI and USB, as the internal clock is not accurate enough. The LPC800-MAX board does have a crystal mounted, but it is not connected, yet I have so far not run into any issues with the board.

Does this rule of thumb not apply to the LPC812 anymore with its internal oscillator? The user manual says "PLL allows CPU operation up to the maximum CPU rate without the need for a
high-frequency crystal." When does it then still make sense to add a crystal to one's design?

Thanks
Christian

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