i.MX6UL custom board consume power even after shutdown?

[punitkumar]

Hi

I'm testing an i.MX6UL custom board for power characteristics and got some unusual results/observations.

My custom board is incorporated with i.MX6UL with micron LPDDR2 (2Gb) and eMMC(4GB). The board is being operated at 198MHz CPU clock. Board is running Yocto and all major peripherals disabled, only some UART, I2C and SPI are in use and i have some other chips on board.

Board is running at 3.7V fixed voltage.

>> I observed that when running on 198MHz the board consumes 67mA. And 100mA is consumed when running at 528MHz.

>> And when put to dorment mode, the board still consume 57mA, which means there is no significant power saving in power down mode.

>> And after shutting down the board, the power, in spite of reducing, increased upto 135mA, now that is something i can't link.

Can anyone help me finding the power required and to reduce the power consumption for low power modes??

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Best Regards

Punit Kumar

[igorpadykov]

Hi Punit

it may be recommended to thoroughly inspect power consumption

of each board chip observing it with oscilloscope and placing  0.02 Ohm resistors

on its power supply pins. General approach is given in sect.3.7. Measuring points

on the MX6UL EVK platform AN5170 i.MX 6UltraLite Power Consumption Measurement

http://www.nxp.com/files/32bit/doc/app_note/AN5170.pdf 

If shutting down the board power current increased, this may be

caused by various components leaks due to esd diodes on inputs - for example

when some voltage is applied to input of unpowered chip.

Best regards
igor
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[punitkumar]

Thanks igorpadykov‌

Perhaps I found the reason for power consumption after soft shutdown. In the EVK i have, after shutdown, the PMIC_ON_REQ pin goes low which in turn switch off all the power regulators, but in my board, it doesn't happen and the power is still consumed at VDD_ARM_SOC_IN (1.4V).

Can you tell me why this is happening?

Best Regards

Punit Kumar

[igorpadykov]

Hi Punit

please look at

https://community.nxp.com/message/828921?commentID=828921#comment-828921 

Best regards
igor

[punitkumar]

Thanks igorpadykov‌

Can you please tell me why after soft shutdown, PMIC_ON_REQ doesn't assert.

If this action needed to be enabled? And how to?

Is there anything needed to be added to .dts file?

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Best Regards

Punit Kumar

[punitkumar]

Actually the problem is with the zimage file. I'm using zimage file supplied with the mfgtool and PMIC_ON_REQ doesn't work.

But if i replace the file with the one given with the imx6ul_14x14_evk sdk, the signal PMIC_ON_REQ goes low after software shutdown and put the system to power down except SNVS. That's what i want.

But i can't use this working zimage file as the serial console hangs up somewhere (i don't know why) (but doesn't hang every time).

Thanks for your support igorpadykov‌

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Regards

Punit Kumar

[igorpadykov]

Hi Punit

I believe you can compare board image with i.MX6UL EVK, debugging

driver in linux/drivers/power/reset/syscon-poweroff.c

from imx6ul.dtsi:
http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/tree/arch/arm/boot/dts/imx6ul.dtsi?id=re...
                snvs_poweroff: snvs-poweroff {
                    compatible = "syscon-poweroff";
                    regmap = <&snvs>;
                    offset = <0x38>;
                    mask = <0x61>;
                };

Best regards
igor

[punitkumar]

Hi igorpadykov‌

Thanks

I found after comparing the files that the board file is having mask=0x60, rest is okey.

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Regards

Punit Kumar