LPC Microcontrollers中的主题 LPC1768 maximum frequency is really 100MHz?

LPC1768 maximum frequency is really 100MHz?

lpcware — Wed, 15 Jun 2016 17:37:26 GMT

Content originally posted in LPCWare by giusloq on Tue Jan 12 06:13:33 MST 2016
I started with a new board based on LPC1768. I started with some files available from NXP examples and I call the funcion Chip_SetupIrcClocking().

void Chip_SetupIrcClocking(void)
{
/* Disconnect the Main PLL if it is connected already */
if (Chip_Clock_IsMainPLLConnected()) {
Chip_Clock_DisablePLL(SYSCTL_MAIN_PLL, SYSCTL_PLL_CONNECT);
}

/* Disable the PLL if it is enabled */
if (Chip_Clock_IsMainPLLEnabled()) {
Chip_Clock_DisablePLL(SYSCTL_MAIN_PLL, SYSCTL_PLL_ENABLE);
}

Chip_Clock_SetCPUClockDiv(0);
Chip_Clock_SetMainPLLSource(SYSCTL_PLLCLKSRC_IRC);

/* FCCO = ((44+1) * 2 * 4MHz) / (0+1) = 360MHz */
Chip_Clock_SetupPLL(SYSCTL_MAIN_PLL, 44, 0);

Chip_Clock_EnablePLL(SYSCTL_MAIN_PLL, SYSCTL_PLL_ENABLE);

Chip_Clock_SetCPUClockDiv(2);
while (!Chip_Clock_IsMainPLLLocked()) {} /* Wait for the PLL to Lock */

Chip_Clock_EnablePLL(SYSCTL_MAIN_PLL, SYSCTL_PLL_CONNECT);
}

It seems to me that function configures the CPU with a 120MHz. I measured 12MHz frequency at CLKOUT pin (configured with a divisor of 10). The chip seems working well.

Am I overclocking the CPU and its running is not reliable in this condition?

Re: LPC1768 maximum frequency is really 100MHz?

lpcware — Wed, 15 Jun 2016 17:37:26 GMT

Content originally posted in LPCWare by vtw.433e on Tue Jan 12 08:00:43 MST 2016
LPC1768 is 100Mhz
LPC1769 is 120MHz

Apart from the max frequency they are the same chip. Driving a LPC1768 at a higher frequency may well work, but it is likely to fail earlier - like any other overclocking

Re: LPC1768 maximum frequency is really 100MHz?

lpcware — Wed, 15 Jun 2016 17:37:27 GMT

Content originally posted in LPCWare by mc on Tue Jan 12 10:19:28 MST 2016
hi giuslaq,
It may work but NXP can't guarantee it will work over the full range of temperature and voltage.