AM2431: Low-power EtherCAT design

John Ford

Part Number: AM2431
Other Parts Discussed in Thread: AMIC110, , AM2432

Tool/software:

Hello, I have a working design in production using the AMIC110 processor, and I would like to update it to run with one of the Sitara microcontrollers. My aim is mainly to reduce power needed to run the board. To do this, I am planning to reduce the I/O voltage to 1.8V for the PHYs and the ADC that I use. This will save a few hundred milliwatts. In addition, I can do without the DDR3 RAM on my board if I use a microcontroller with on-board memory, saving a bit more power.

I have been looking through the formidable array of microcontrollers TI has that support EtherCAT, and I was looking for a recommendation for the lowest power solution. I am using the 83822 PHY, as it seems to be the lowest-power and it works on my AMIC110 based system. The AM2431 seems to be the lowest power microcontroller I've run across that supports the EtherCAT firmware in the PRUs. Do you have any suggestions for me in my quest? I realize it's not exactly a good idea to use EtherCAT in a power-constrained system. It's not up to me!

My secondary aim is to use a supported RTOS, as TI-RTOS is no longer supported on the AMIC110, and FreeRTOS is supported only on newer processors.

Thanks!

John Ford

4 months ago

0 Paula Carrillo 4 months ago

TI__Mastermind 40580 points

Hi, today it is a holiday in India, some of our colleagues there are out of office for a couple days. Please expect delayed response.

0 PratheeshGangadhar 4 months ago in reply to Paula Carrillo

TI__Mastermind 49891 points

You may also consider https://www.ti.com/product/AM2612 for EtherCAT only use case without DDR < 1W power for MCU side is possible. You can try out AM261X-PET-CALC Calculation tool | TI.com

0 John Ford 3 months ago in reply to PratheeshGangadhar

Intellectual 580 points

Thanks. The power estimation tool link seems broken.

0 John Ford 3 months ago in reply to John Ford

Intellectual 580 points

I should have searched for it before replying.

Found it at www.ti.com/.../1.0.0

0 John Ford 3 months ago in reply to PratheeshGangadhar

Intellectual 580 points

I've considered the 2431, 2611, 263x, ND 263Px. It seems from the power consumption estimator that the 2431 is the lowest power option. Could you take a look at my screenshots of the 2 power estimator tools and see if I can improve anything? Or if anything is out of sync with the 2 . I think the 263XX are overkill for my project and would not be better in power consumption, correct?

0 PratheeshGangadhar 3 months ago in reply to John Ford

TI__Mastermind 49891 points

John Ford said:
I think the 263XX are overkill for my project and would not be better in power consumption, correct?

Correct. 263xx will be higher power than 261x.

For AM243: EtherCAT can run at 200MHz ICSSG and need only 3/6 cores. So, 50% utilization might be apt,

For AM261: Ethernet_0/1 can be off/not used. R5F can be 25% load for 200MHz operation.

0 John Ford 3 months ago in reply to PratheeshGangadhar

Intellectual 580 points

Thanks. I adjusted the spreadsheets, and the AM2432 (-1 doesn't have a version with etherCAT enabled!) still takes less power than the 261x. I guess due to the higher core voltage on the 261x. I'll design in the AM2432, I think.

0 Sahana H G 3 months ago in reply to John Ford

TI__Expert 5916 points

Hi John,

I see that the Junction Temperature Tj is set at different values in AM243/ AM261 (38C vs 85C). This needs to be set at the maximum temperature that the device would operate in, and then you would be able to compare the power consumption across devices under this ideal condition. Could you please confirm this?

Thanks,

Sahana

0 John Ford 3 months ago in reply to Sahana H G

Intellectual 580 points

Thanks, Sahana. I missed that field. If I set the temperatures both to 85C, I still get the AM2432 the better option. The AM2432 estimate is 748 mW, and the AM261x estimate is 839. I tried some other temperature values and the result is consistent.

John

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AM2431: Low-power EtherCAT design