OMAP-L137: Powering the L137 D version (456MHz) at a lower frequency

Hi Eric,

Typically voltage scaling on CVDD is permitted, and a useful approach for power savings if you do not need the performance of the CPU/DSP at higher frequencies.

I see how you came to have this question and I have sent out a request for clarification.

The recommended operating conditions table mentions a min CVDD 1.25V for the 456 MHz version (regardless of operating frequency).
It could have stated the min CVDD requirements for CPU/DSP operating upto 375MHz and 456MHz.
Reading it directly makes it seem like the 456 MHz version (DZKB4) always requires 1.3V even when operating with CPU frequency less than 375MHz.

I disagree with that interpretation, but will confirm internally.

Table 3-1. Characteristics of the OMAP-L137 Processor seems to support voltage scaling on CVDD by stating…
CPU Frequency MHz
674x DSP at 375 MHz(1.2V) or 456 MHz (1.3V)
ARM926 at 375 MHz(1.2V) or 456 MHz (1.3V)

Also TRM section 10.2 Power Consumption Overview states “Dynamic power can be reduced by scaling the operating voltage, when the performance requirements are not that high and the device can be operated at a corresponding lower frequency.”

And the power estimation tool allows 1.2V or 1.3V selection (though it does not complain about the combination of 1.2V with 456MHz.

I will let you know when I have found out with confidence that you can supply 1.2V to the 456 MHz version (DZKB4) if it never exceeds 375MHz CPU/DSP frequency.

Regards,
Mark

Thank you Mark for your fast answer. I can see we have the same feeling, but that needs confirmation as we don't want to risk erratic functioning. By the way, do you have any news from the Engineers ?

Regards

Eric

Hi Eric

Sorry for the delay- I am still working with my product engineering team to confirm that it is ok for you to run the 456 MHz part at 375 MHz @ 1.2V Nominal.

I hope to confirm early next week if not sooner. 

Regards

Mukul