MKE02 FLL Recommended Input Frequency Range

ad_sabir86 — Wed, 20 Sep 2023 11:01:09 GMT

Hi NXP Team

I am using Kinetis KE02 family microcontroller MKE02Z64VLD4 with external crystal oscillator 7.3728MHz as I need to generate serial port baud rate of 460800.

I have set the FLL with external crystal in FEE Engaged External Mode, with:

7.3728MHz divide by 256 = 28.8 KHz. This 28.8 KHz is fed to FLL, which then outputs

28.8 KHz * 1024 = 29.4912MHz (and BUS CLOCK at divide by 2 = 14.7456 MHz)

BUT

As per data sheet of MKE02, the FLL is optimized for 32-40 MHz output frequency range.

Input of FLL is recommended to be in the range of 31.25 KHz to 39.0625 KHz

What does it actually means?

Can I use FLL using 7.3728MHz external crystal and get a core frequency of 29.4912MHz?

Will FLL maintain the LOCK for this frequency (29.4912MHz)?

Or I cannot use the above scheme, as 28.8 KHz is lower than the recommended minimum of 31.25 KHz.

Kinetis MicrocontrollersのトピックMKE02 FLL Recommended Input Frequency Range

MKE02 FLL Recommended Input Frequency Range