Is there any way to use any frequency other than 24 MHz for the high speed clock input?

[sdgsrhsgfasdfas]

I have a low-jitter 16 MHz clock that I am using for the ADC. I want the MCU to be synchronized to this clock. Is there any way to use a 16 MHz clock as the input to the high speed clock input, or does it need to be 24 MHz?

[mjbcswitzerland · Accepted solution]

Hi

The i.MX RT parts are specified to operate from 24MHz - for example see the data sheet showing that the oscillator (or crystal) should be 24.0MHz with no +/- range):

The frequency is used as reference for various PLLs which also, depending on design, are used to provide exact frequencies for Ethernet and USB operations, where deviations would make them unusable.

Since internal PLLs are designed to work with a certain frequency range other frequencies may cause these to fail.

Therefore, although simple configurations that run internal clocks directly from the external clock input (avoiding PLLs and avoiding communication interfaces with exact frequency requirements) may be operational this would generally be a large restriction and practically only a 24MHz reference should be used.

Regards

Mark
[uTasker project developer for Kinetis and i.MX RT]
Contact me by personal message or on the uTasker web site to discuss professional training or product development requirements