lpcware

IRC as clock source for USBCLKSEL?

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by 1234567890 on Wed Jan 07 11:36:13 MST 2015
IRC has a fixed value of 12 MHz, but is the default input for USBCLKSEL, which is followed by a clock devider (and no PLL).

All other inputs of USBCLKSEL (system oscillator, USB PLL and main clock) can deliver frequencies >= 48 MHz which can be devided to the required 48 MHz for the USB peripheral.

So when is it useful to deliver 12 MHz (or less) to the USB peripheral?

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