SDRAM vs LPDDR (AM17xx vs AM18xx)

I would recommend using the power estimation tools to determine this for your use case:

AM17x: http://processors.wiki.ti.com/index.php/AM17x_Power_Consumption_Summary

AM18x: http://processors.wiki.ti.com/index.php/AM18x_Power_Consumption_Summary

-Tommy

These pages and spreadsheets, which I already examined, do not contain information on SDRAM and LPDDR power consumption.  Please address this question.  I'm not looking for exact numbers, just a relative power consumption comparison.  The data rate of SDRAM is lower than LPDDR so I don't know which would be lower power.

I'm not sure that I completely understand your feedback.

The spreadsheets do include line-item EMIF power consumption numbers for SDRAM on AM17xx and for both DDR2 and mDDR on AM18xx.  Power consumption numbers vary depending on use-case so that's why the spreadsheets were recommended.

Also, I'm not sure that I follow the comment about SDRAM having a lower data rate.  The overall EMIF data rate is Data Frequency x Data Bus Width.  The AM17xx SDRAM data bus is 32-bits with single data rate and the AM18xx DDR data bus is 16-bits with double data rate.  Given the same reference clock frequency, the overall SDRAM and DDR data rates are essentially the same.

-Tommy

In the Power spreadsheet of AM18xx; when you choose "Typical - 300 mhz" (for example) then for

DDR: == 279.69 mw

mDDr == 267.93mw

similar difference for 456mhz .

(under column "Other" you can choose memory t ype.)

However the Memory chip itself has different consumption between DDR and mDDR which you get from memory's datasheet.

Also setting the drive current to 60% in the cpu affects power usage!

Try similar comparison on the AM17 side too.

hope it helps.

asad

I need to know the relative power difference between the DDR and mDDR chips themselves.  We are in the evaluation stage in regards to this customer opportunity.  The customer hasn't decided on the processor or memory yet so we can't look up the memory's power consumption.  But the customer needs our help in considering the overall power of the system.

Hi
The power consumption spreadsheets for the AM1xx devices only comprehend the power w.r.t to the external memory controller and SOC I/Os, it will not comprehend the power consumption of the memory chips itself. This true for any interface, as what you hook up to the memory, serial, parallel ports is going to be user dependent. Recommend that you look at some key memory datasheets to generate some estimates for memory chip power consumption. You could possibly start with SDRAM and DDR2/mDDR memories supported on TI evaluation platforms.

In addition, some high level differences that make AM18xx more lucrative for customers that are sensitive to power management and lower power etc compared to AM17xx 

1) AM18xx supports DVFS ( multiple OPPs including a 1.0 V OPP)

2) AM18xx supports deep sleep mode ( overall standby power can be lower compared to AM17xx if customer can leverage the Deep Sleep mode)

3) AM18xx support dual LVCMOS I/O for most of the interfaces, allowing user to have predominantly 1.8V IOs, where as AM17xx all IOs are 3.3V (except USB 1.8V supplies)

Hope this helps.

Regards

Mukul