Internal vs External OSC

[lpcware]

Content originally posted in LPCWare by Muis on Fri Oct 04 08:36:22 MST 2013
I have an external crystal on my board, but are there any advantages/downsides of using the IRC instead?

Will the IRC use less power? Wake up faster from deep sleep? Or is there no reason to use the IRC when you have XTAL input?

[lpcware]

Content originally posted in LPCWare by NXP_Paul on Fri Oct 04 09:23:00 MST 2013
It is always advisable to use the IRC whenever possible, because it uses less power, you can wake up faster, and is less expensive than using an external crystal.
The IRC has an accuracy of 1%, over the entire voltage and temperature range.  While this is good enough for most applications, it is not accurate enough for peripherals such as USB.