topic Re: Kinetis K11A power consumption in LLS mode in Kinetis Microcontrollers

Kinetis K11A power consumption in LLS mode

amirshteinberg — Tue, 20 Sep 2016 07:19:52 GMT

Hi,

I am using MK11DN512AVLK5 MCU in LLS mode.

In the datasheet it says that the power consumption is supposed to be up to 4.8uA.

When I measure the power consumption on my board is around 50uA.

What can be the reason for this?

Thank you

Amir

Re: Kinetis K11A power consumption in LLS mode

Hui_Ma — Wed, 21 Sep 2016 08:12:09 GMT

Please check the MK11DN512AVLK5 chip mask set at chip surface second print line.

There is an errata file for mask set 0N89E chip with below errata info:

Wish it helps.

Have a great day,
Ma Hui
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Re: Kinetis K11A power consumption in LLS mode

amirshteinberg — Wed, 21 Sep 2016 10:50:51 GMT

Hi,

Thank you for your answer.

This errata does not apply to my MCU as the mask written on it is 0N62J.

Even if the power consumption is higher then what is stated in the datasheet, I don't think it explains the difference between starting the application from IAR (in this case the SRS register states it is a SW reset) and starting it using POR

Re: Kinetis K11A power consumption in LLS mode

Hui_Ma — Thu, 22 Sep 2016 08:05:30 GMT

If you also disconnect the J-Link debugger tool from the board when perform SW reset or POR reset?

If the code run from the internal Flash? If yes, the power consumption should be same when enter into LLS low power mode.

Thanks for the attention.

Re: Kinetis K11A power consumption in LLS mode

egoodii — Thu, 22 Sep 2016 11:46:33 GMT

The 'usual' explanation for high sleep current is floating inputs. In this case, since there is a difference if the debugger is connected, I would start by considering the JTAG-pin-states.

Re: Kinetis K11A power consumption in LLS mode

amirshteinberg — Thu, 22 Sep 2016 13:01:50 GMT

Hi,

The code is running from the internal Flash.

It is a good idea to try disconnecting the J-Link after POR, I will try it on Sunday and report back the results.

Thanks,

Amir

Re: Kinetis K11A power consumption in LLS mode

amirshteinberg — Thu, 22 Sep 2016 13:04:16 GMT

Hi,

these are the possible options fot the JTAG pins:

do you think I should configure them as GPIO inputs before entering LLS?

Re: Kinetis K11A power consumption in LLS mode

mjbcswitzerland — Thu, 22 Sep 2016 14:23:22 GMT

Hi Amir

Conserning floating inputs, there are a couple of other posts where this is confirmed:

Dealing with uA,PORTC5,when forced low draws less current than floating,why?

https://community.nxp.com/message/499153?commentID=499153#comment-499153

They also show that increases in the order of magniture that you are experiencing are quite normal if the state of the device is not carefully controlled in the low power state.

A simple test is to carefully touch pins on the processor (or possibly at other locations on the board) with your finger and see whether the consumption fluctuates as a result of it. Identfy which pins or elemenst are sensitive and then take appropriate action as necessary.

Regards

Mark