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LPC54102 crashes with main clock > 24 MHz

Question asked by Michel Kuenemann on Mar 15, 2017
Latest reply on Apr 21, 2017 by Marc Prager

Hello all,

I am currently developing an application on an LPC54102 clocked by its IRC (12 MHz). The application is almost coded now, and recently I started to implement the PLL in order to get higher clock frequencies, like 24, 36, 48, ... 96 MHz. 


I am using the CLKOUT pin to monitor the main_clock and I have verified that I generate precisely each integer multiple of 12 MHz, up to 96 MHz. I have taken care to have a CCO frequency comprized within the 75 / 150 MHz limits. The PLL works in "normal mode". The PLL locks immediately and I do no see any visible jitter on the CLKOUT signal.


The target is an LPCxpresso 54102 board. I do not use the LPCopen library.


As long as I stay with 12 or 24 MHz, the micro works fine, but as soon as I try to use any higher frequency, it crashes as soon as I switch to the PLL clock.


I am wondering if there is maybe an additional configuration, related to the power management to perform in order to gain access to higher core frequencies ? I  did not find anything relevant until now.


Thank you for your support.