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idata
Community Manager
1,721 Views

Spread Spectrum

Hello!

I want to know where I can find the knowledge about Spead Spectrum using in PCH?

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10 Replies
CarlosAM_INTEL
Moderator
118 Views

Hello Linch,

Thank you for contacting the Embedded Design Community.

In case that you refer to the Spread Spectrum Clocking (SSC), its principle is that the clock chip continually varies its output frequency over a small range (0.5%), centered around the base frequency. The benefit of SSC is realized in the resulting reduction of EMC emissions of the system. Many designs utilize SSC to meet regulatory EMC targets. In most clock chips using SSC is programmable or strap-able option. This information and more details can be found in Clocking section of the http://www.intel.com/content/dam/www/public/us/en/documents/white-papers/ia-platform-basics-paper.pd... Intel(R) Architecture Platform Basics.

In case that you need more specific information please refer to the documentation of each Platform Control Hub (PCH) documentation.

Best Regards,

Carlos A.

idata
Community Manager
118 Views

Hello Carlos,

Thanks for replying me.I am new here.Recently I will do a report about Spead Spectrum Clock.Of course I have seen some datasheets for Intel chipset.But these ones only tell me which clock does the PCH output,and which one use Spead Spectrum Clock technology.I want to know how it works.Maybe it's a inordinate request.However,thank you very much for answering my question.I was an intern engineer for ASUS.This is the first time to ask question in Intel embedded community.I'm very exciting.Thank you!

Best regards

Lich_Wang

CarlosAM_INTEL
Moderator
118 Views

Hello Linch,

Thanks for your reply.

The SSC is related to the Electromagnetic Interference (EMI). In order to help you, could you please let us know what is the platform (processor and chipsets) related to your consultation?

Thanks in advance for your cooperation.

Best Regards,

Carlos A.

idata
Community Manager
118 Views

Hello Carlos,

As a new one of ASUS,I'am sorry to say that the only thing I know about the product offered to me is using the Broadwell Platform.As for the chipset and processor,the circuit only tells me a mixture of numbers and letters about the chipset,just like CL8064701318105.I ask other engineer for help.But they don't know either because we are in charge of debug ,not designing circuit.Thank you very much anyhow.

Best regards

Lich_Wang

CarlosAM_INTEL
Moderator
118 Views

Hello Linch,

Thanks for your reply.

The information that may help you is stated on page 8 of the http://download.intel.com/support/motherboards/desktop/sb/biosglossarybymenu_v13.pdf BIOS Settings Dictionary.

Please let us know if this information is useful to you.

Best Regards,

Carlos A.

idata
Community Manager
118 Views

Hello Carlos,

I think I have got the answer I want about SSC.Now I have a small question.In order to observe the difference between the clock using 2.0% SSC and the normal clock,we choose the differential clock PCIe_Wlan and measura its waveforms mentioned above as we don't have the Spectrum Analyser.I can see the waveform waving around 100MHz when we don't use SSC.The waveform waves around the 98MHz when we use 2% SSC.Can I regard it as ture? I also see that when I adjust the rate of SSC greater than 0.7%.The notebook can't identify its HDD.So we can't enter into OS.I pay attention to the limit provided in the datasheet of HM65.It rules 5% SSC.I want to know if this is a normal appearance.

Best regards

Lich_Wang

idata
Community Manager
118 Views

Hello Carlos,

Sorry!The limit I have mentioned is 0.5% ruled in HM65.Thank you !

best regards

Lich_Wang

CarlosAM_INTEL
Moderator
118 Views

Hello Lich,

Thanks for your reply.

Reviewing the 98 MHz value is correct because it is -2% of 100MHz.

On the other hand, please keep in mind that 0.7 % is greater than 0.5%, which is the suggested. It is out of the stated in the documentation also it is an unverified and unsupported situation.

On the other hand, more information related to SSC is stated in section 2.1, on pages 4 and 5 of the http://www.intel.com/design/pentiumii/applnots/24333402.PDF Application Note (AP)-589 Design For EMI document # 243334.

Please let us know if this information is useful to you.

Best Regards,

Carlos A.

idata
Community Manager
118 Views

Hello Carlos,

I think you have sovled all my questions.Thanks for reply me patiently.I wish you have a nice day!

best regards

Lich_Wang

CarlosAM_INTEL
Moderator
118 Views

Hello Lich,

We are glad to hear that the provided information was useful to you.

Best Regards,

Carlos A.