I am trying to make an eval-board MCB2368 work at 19.968MHz. According to the user manual, 275<Fcco<550MHz. However, at the errata sheet version 1.1 for LPC2368 is said that the limit for Fcco is 290MHz. So, I realize we have the range 275<Fcco<290MHz for LPC2368.
The LPC2368 documentation says also that 1<N<256 and 1<M<32768.
To match my needs, I found the values N=125, M=1456 (for these values I got Fcco=279.552MHz), both inside the respect range.
My problem is that for any value of N bigger than 37 the PLL doesn't work.
Some one can explain me if I am doing something wrong or is it really missing information at LPC2300 documentation?