topic Re: LPC11xx 50MHz in LPC Microcontrollers

LPC11xx 50MHz

lpcware — Wed, 15 Jun 2016 19:40:16 GMT

Content originally posted in LPCWare by marcossmart on Tue Dec 17 18:30:55 MST 2013
You have application note NXP for operate LPC1114 whith 50MHz?

Re: LPC11xx 50MHz

lpcware — Wed, 15 Jun 2016 19:40:17 GMT

Content originally posted in LPCWare by R2D2 on Tue Dec 17 18:54:03 MST 2013
UM10398 is describing PLL setup:

See. Table 46. PLL configuration examples

Just calculate new values with your changed crystal...

Re: LPC11xx 50MHz

lpcware — Wed, 15 Jun 2016 19:40:18 GMT

Content originally posted in LPCWare by marcossmart on Tue Dec 17 22:10:33 MST 2013
The maximum value of 25MHz crystal is supported?
Only need to change the SYSPLLCTRL? What would be the correct value to operate and 50MHZ and 25MHz crystal?

Re: LPC11xx 50MHz

lpcware — Wed, 15 Jun 2016 19:40:18 GMT

Content originally posted in LPCWare by R2D2 on Wed Dec 18 00:46:00 MST 2013

Quote: marcossmart
The maximum value of 25MHz crystal is supported?

Quote:

• Clock generation:
– 12 MHz internal RC oscillator trimmed to 1% accuracy that can optionally be used as a system clock.
– Crystal oscillator with an operating [color=#f00]range of 1 MHz to 25 MHz.[/color]

Quote: marcossmart

Only need to change the SYSPLLCTRL?

Yes.

Quote: marcossmart

What would be the correct value to operate and 50MHZ and 25MHz crystal?

Quote:
3.11.4.1 Normal mode
In normal mode the post divider is enabled, giving a 50% duty cycle clock with the
following frequency relations:
(1)
To select the appropriate values for M and P, it is recommended to [color=#f00]follow these steps[/color]:

1. Specify the input clock frequency FCLKIN.
2. Calculate M to obtain the desired output frequency FCLKOUT with
M = FCLKOUT / FCLKIN.
3. Find a value so that FCCO = 2 x P x FCLKOUT.
4. Verify that all frequencies and divider values conform to the limits specified in
Table 10.
5. Ensure that FCLKOUT < 100 MHz.

Wow, that's really difficult for 25 MHz:

-1. FCLKIN = 25 MHz

-2. M = FCLKOUT / FCLKIN = 50 MHz / 25 MHz = 2

-3. P = 2, FCCO = 2 x 2 x FCLKOUT = 200 MHz

-4: 156 MHz < 200MHz < 320 MHz

Re: LPC11xx 50MHz

lpcware — Wed, 15 Jun 2016 19:40:19 GMT

Content originally posted in LPCWare by CVAS on Sun Dec 22 10:08:16 MST 2013
http://www.lpcware.com/content/nxpfile/lpc11xx-main-pll-calculator