Core Frequency of LS2088A

[subashrajaram]

Hi,

I am working with LS2088A processor. In the reference manual they have mentioned The maximum CPU frequency is 2.0GHz. 

But from the RCW settings it can be changed between 800Mhz to 1600Mhz  it seems (based on the value of SYS_PLL_RAT) .

My question is How to Change the Core frequency to 1800MHz or 2Ghz?

[alexander_yakov]

Sorry for delayed response to that.

Maximum core and DDR frequencies, supported by particular device, may be determined from partnumber using partnumber decoding information, provided in LS2088A device datasheet, Chapter 8 "Ordering Information".

For this moment orderable options are 1.6, 1.8 and 2.0 GHz for core and 1.6, 1.867 and 2.133 GHz.

For core frequency 2.0Ghz - this is maximum supported value, the actual core frequency is configurable and may be in range from 800 Mhz to 2.0 Ghz. This configuration is performed by selecting desired multiplier for input frequency (SYSCLK or DIFF_SYSCLK). Multiplier is configured in RCW and may be in range from 6:1 to 24:1, input frequency may be in range from 83.3 to 133.3 Mhz.

Futher, there are sereral PLLs and several 1/2, 1/4 and 1/3 dividers for each PLL, so core frequency may be taken from different sources, this is also selected in RCW.

For better understanding, here is clock distribution Figure from LS2088A Reference Manual

Have a great day,
Alexander
TIC

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