URGENT:LPC2378 USB not Recognized,PLL setting

Hi Friends,

I am using LPC2378 processor with 16 MHz crystal oscillator.I am trying to connect the USB CDC but the USB device not recognized by PC.

The same code using the 12 MHz oscillator is working.

Fcco value = 288 MHz
Crystal oscillator value = 12MHz
PLL 'M' value = 12
PLL 'N' value = 1
USBCLKCFG,USBSEL value = 6

Result : The USB CDC is detecting in PC

Fcco value = 288 MHz
Crystal oscillator value = 16MHz
PLL 'M' value = 9
PLL 'N' value = 1
USBCLKCFG,USBSEL value = 6

Result : The USB CDC is Not Recognized

I am using the Formula to calculate the M value is
M = Fcco/2xcrystal oscillator vale

Please help me to solve this problem.

With Regards,
Murthy.R

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