18f2523 20Mhz compatible whith HSPLL mode?

JULIEN LAFFITTE · Joined: 28 Mar 2007 Posts: 20

hello
I use a 18f2523 and i want to know if i can use a 20Mhz cristall oscilator whith the HSPLL(H4) mode to have a 40Mhz internal frequencie? Embarassed

thanks

Bill Boucher · Joined: 04 Feb 2005 Posts: 34 Location: Chatham,ON,CA

The chip is a 10 MIPS max microcontroller so the max internal osc is 40 MHz. That said, your external clock source would be multiplied x4 by the PLL. So, if the internal max is 40 MHz, then the external max is 10 MHz.

To directly answer your question, no, you can't use a 20MHz crystal. The range with PLL enabled is 4 to 10 MHz.