DLPC900: DLPC900 Spread Spectrum

Greetings Markus

The spread spectrum feature is meant to reduce EMI by purposely inducing a controlled amount of jitter on all of the signals in the in the DMD interface. I do not know the specific reason why this feature is not enabled by default, but here are my thoughts:

Meeting the DMDs High-speed interface waveform quality and timing can be tricky, especially at the highest pattern rates. Having the spread spectrum feature enabled by default might cause timing problems in certain applications that might be in the very edge of valid timing requirements.

In any case I will ask one of our engineers which is most familiar with the controller, unfortunately he is out of his office until Friday but he might respond to my email. I will let you know his input by then.

Best Regards
Jesus

Hi Jesus,

Many thanks for clarification. I understand the decision to withhold the enabling of the feature by default.

EM radiation is actually a topic we are heavily worried about - even with the reference board provided by TI we are way beyond the levels given by the industrial standards. Could you elaborate some more what you mean by adequate shielding? Is there any documentation about it?

BR

Markus

Hi Markus

The EVM TI provides are not meant to be used as end equipment, they are meant for evaluation, research, or development purposes.

What was meant by "performing adequate shielding" is that a EMI shielding should be implemented to meet the application specific emission requirements, that could be a consumer product or part of an industrial process.

We do have some guidelines in PCB design meant to reduce EMI here: www.ti.com/.../szza009.pdf and one on microcontrollerr system www.ti.com/.../snoa382.pdf

I hope this answered your questions.

Best Regards
Jesus

Hi Jesus

Thanks for the documentation. They are however, while perfectly fitting for the intended purpose, written in a rather general fashion and not tailored to our needs.

I do understand that the TI EVM are not intended to be used as end equipment, however, never seeing an actual DLPC design that does fit the the industrial EMI standard needs is making me uneasy. Are there real life industrial examples, where these standards have been met? Might there be direct support from TI which we could access in our specific case?

THanks in advance,

Markus