topic Re: iMX6SX's DDR3L consumption in i.MX Processors

iMX6SX's DDR3L consumption

tonioch — Fri, 24 Jul 2015 13:49:49 GMT

Hello every one,

I'm currently measuring the iMX6SX's consumption on the iMX6SX-sabreSD board. With the application note AN5050 about power consumption, I've managed to enter into the deep-sleep mode and the system idle mode.

I've also put resitors of 20mΩ at the different measuring points in order to measure the voltage drop over those points, and to determine the power consumption.

The VDDARM_SOC_IN and VDDHIGH_IN's power data are nearly the same as Freescale's but the DDR3L isn't at all.

It's written in the AN that the power consumption should be around 22 mW for the DDR3L I/F + memories but in my case, it uses 500 mW.

I think that even if the system is in DSM or Idle mode, the DDR3L aren't in self refresh state.

Does anyone know how to force the DDR3L to be in this mode of self-refresh ? Is there another command to add?

Sincerely,

Antoine CHARON

PS: I'm using the Linux Version 3.10.53-1.10_ga+g496fbe0 provided by Freescale with the board

Re: iMX6SX's DDR3L consumption

igorpadykov — Mon, 27 Jul 2015 01:39:38 GMT

Hi Antoine

one can check if M4 is accessing DDR, so for measurements boot only A9 core.

According to DDR3 specification memory goes to self-refresh

putting CKE low, i.MX6SX MMDC asserts it low automatically, this is described

in sect.40.4.6.2 Self refresh SoloX Reference Manual

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6SXRM.pdf

Best regards

igor

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Re: iMX6SX's DDR3L consumption

tonioch — Mon, 27 Jul 2015 15:18:48 GMT

Hi Igor,

Thanks for you answer. I tried to do the measurement without the M4 booted, but the problem remains..

Memory doesn't go in self-refresh automatically in my case, do you know if it exists some procedure to do it manually?

Sincerely,

Antoine

Re: iMX6SX's DDR3L consumption

igorpadykov — Mon, 27 Jul 2015 15:34:34 GMT

Hi Antoine

below detailed steps

Best regards

igor

Re: iMX6SX's DDR3L consumption

tonioch — Tue, 28 Jul 2015 08:38:47 GMT

Hi Igor,

Yes that's exactly what I did. I've replaced all the shunts and other 0Ω resistors you mentionned in your document by 20 mΩ precision resistors.

After I entered the command for DSM, I have exactly the same messages coming back from UART.

The only consumption differences are for the two precision resistors R373 (DDR3L) and SH7 (SYS_3V8).

From the first (R373), I measured 7.535 mV, so the memories are using 497 mW.

From the second (SH7), I measured 5.044 mV, so the SYS_3V8 power rail is using 958 mW.

I have the same board (SCH-27962 Rev. C), but I don't use exactly the same SW Image (3.10.53-1.10_ga+g496fbe0).

Do you think the problem could come from that sofware's difference?

Sincerely,

Antoine