Proper PLL Calculator for LPC177x/178x

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by MikeSimmonds on Tue Sep 18 19:28:21 MST 2012
The 17xx PPL Calculator on the NXP site is only useful for 176x etc. As the 177x and 178x
have a very different (and brain damaged) PLL block.

So I have made a first stab at a 177x/178x specific calculator.

As I am mostly a novice with Excel (and only have Excel97) I don't know how to colour cells with Clock speeds that are legal but unobtainable (because no legal Fosc exists).

So only use results on rows where there is a legal Fosc value in the left hand grid.

To use, just enter the crystal speed (in MHz). E.g. 12 for 12Mhz, or 18.432 etc.

Notice how limited this PLL block is compared to the one on the 1769. Over half of the potential settings are unusable due to the limits placed on crystal speed and how they have specified the internal oscillator.


Original Attachment has been moved to: LPC1778-PLL-Calculator.zip