topic Re: Current consumption on FRDM-KL05 in Kinetis Microcontrollers

Current consumption on FRDM-KL05

pramodtm-b46240 — Wed, 25 Jun 2014 07:33:58 GMT

Hi,

I'm trying to implement low power modes on KL05 frdm board and measure the current consumption in different modes. Reffering to the schematics, I found out that MCU VDD is connected to P3V3_MCU which is coming from the jumper J4 which is DNP. But a 0 ohm R27 is in parallel to J4. I removed the R27 and soldered a jumper at J4 for putting a multimeter.

But then , what I noticed is MCU is still getting power . I checked the voltage on J4,2 [without putting the jumper], I'm seeing 1.8V. I'm confused from where the voltage is leaking.

Has anybody faced a similar issue? or am i missing something here?

P S : The resistance accross the jumper is 600k ohm

Thanks

Re: Current consumption on FRDM-KL05

mjbcswitzerland — Thu, 26 Jun 2014 19:12:48 GMT

There are a number of connections between the KL05 and the Open-SDA interface.

Very probably the you are measuring a voltage derived from there.

Regards

Mark

Re: Current consumption on FRDM-KL05

pramodtm-b46240 — Fri, 27 Jun 2014 05:37:44 GMT

Hi Mark,

I'm reffering to FRDM-KL05 schematics. J4.2 is connected to P3v3_MCU which is connected to VDD of MCU. There is no connection between J4.1 and J4.2 . R27 is also removed. So if checked, we can see that MCU VDD is not connected to any pin now. I want to connect the multimeter in ammeter mode between J4.1 and J4.2. But without connecting the MCU is working but at a lower VDD of 1.9V This I'm measuring at J4.2 not anywhere else. I'm suspecting there is a leakage from somewhere to the VDD of MCU.

But can't make out.

Thanks,

Re: Current consumption on FRDM-KL05

Paul_Tian — Fri, 27 Jun 2014 07:12:21 GMT

Hi, Pramod

This issue is caused by K20 in SWD still communicates with KL05. So you detect the P3v3_MCU still has voltage value. Hope my reply can resolve your confuse.

Best Regards

Paul

Re: Current consumption on FRDM-KL05

pramodtm-b46240 — Fri, 27 Jun 2014 08:12:19 GMT

Hi Zhe,

Thanks for the reply

Do you mean that since K20 is communicating, I get a voltage on VDD of the MCU?

If that is the case, how do you measure current consumption in various power modes?

Thanks,

Re: Current consumption on FRDM-KL05

mjbcswitzerland — Fri, 27 Jun 2014 12:17:55 GMT

When the KL05 is not powered the voltages from the K20 are probably measurable since teh KL05 is not operatimng in a "defined state". This however probably doesn't cause any difficulties when the KL05 is powered normally and in a low power mode since then also the connection pins are defined and so there will be no such "leakage".

Regards

Mark

Re: Current consumption on FRDM-KL05

pramodtm-b46240 — Fri, 27 Jun 2014 13:53:09 GMT

Thanks Mark,

I just measured the voltage. Since I made out that the MCU is not fully powered off, I didn't continue my experiment on KL05. Shifted to FRDM-KL25. Once, I finish that, I'll start on KL05.

But, FYI, The MCU is fully powered off when I disconnect the cut trace between jumper pins J4 of FRDM-KL25 unlike on FRDM-KL05 while both use K20 for openSDA

Thank you very much for your replies.