LPC55S28 Oscillator Requirements with High Speed USB

zach890 — Mon, 14 Jun 2021 15:46:00 GMT

I'm working on a new design with the LPC55S28 that will be utilizing high speed USB for data connections. Reading the data sheet and the user guide it's not completely clear what the external oscillator requirements are for the chip.

Both the data sheet and the user guide refer to the high speed USB clock as the 16MHz clock but section 45 (USB Phy) of the user guide mentions that XO32M can be configured to 16, 19.2, 20, 24, or 32MHz. Does this mean that an external crystal oscillator can operate at any of those frequencies or does it have to be 16MHz? Alternatively is an external oscillator needed for high speed USB the datasheet and user guide implies that it is a requirement.

Thanks for the help!

Re: LPC55S28 Oscillator Requirements with High Speed USB

Alice_Yang — Wed, 16 Jun 2021 09:54:02 GMT

Hello ,

"Does this mean that an external crystal oscillator can operate at any of those frequencies"

->> Yes.

topic Re: LPC55S28 Oscillator Requirements with High Speed USB in LPC Microcontrollers

LPC55S28 Oscillator Requirements with High Speed USB

Re: LPC55S28 Oscillator Requirements with High Speed USB