Reduce startup power of Kinetis

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Reduce startup power of Kinetis

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carlostadeoorte
Contributor III

Hello community,

I would really appreciate any insight with reducing the power while doing a cold start for the KL03.

Some background:

I am using a KL03, custom board. I want to minimize the power used during a cold start as Vdd rises to settle at 1.8V. In order to quantify this, I didn't populate any components other than a 10k resistor between Vdd and Vss and a 1uF between Vdd and Vss. Then I would start with Vdd=0V and raise Vdd on 0.2V increments.  I would look then at the power draw using an ammeter (I dont know the voltage drop of the ammeter). I also looked at the voltage on the reset pin

Here are my results:

Vdd   |  I_vdd    |   V_reset

0            0              0

0.2         0              0.17

0.4         6u            0.4

0.6         33u          0.6

0.8         180u        0.1

1.1        300u          0

1.2        440u          0

1.4        370u          0

1.6       320u           0

1.7       20u            1.7   <<--- application is supposed to use 30uA, so we are good here

Then, I removed the resistor between Reset and Vdd ( there is an internal 20k-50k pup resistor there anyway).

Vdd   |  I_vdd    |  

0            0             

0.2         0             

0.4         0u            

0.6         40u         

0.8         130u       

1.0         200u        

1.2        210u         

1.4        150u         

1.6       370u         

1.7       20u          

So, removing the resistor between Reset and vdd seems to help a bit at the risk of having noise on Reset. I would like to reduce the power consumption even more _WITHOUT_ external active components (resistors, caps, etc are ok).

Any suggestions on what to do would be greatly appreciated..

I don't think it's relevant, but upon powering up, the chip sets  LVDV on, sets it's  clock at 60kHz and then toggles an LED at ~2Hz while entering and leaving VLPS (using LPTM to wake up).  The results posted are WITHOUT the LED, but the functionality was verified with the LED

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david_diaz
NXP Employee
NXP Employee

Hello Carlos,

Please be aware that if you remove the resistor from the reset pin, your application will be susceptible to the noise and probably to undesired reset events.

I am afraid that there is no way to reduce the power consumption during the startup of the MCU.

You can enter to different low-power modes by software once the device is started.

Please refer to the following document in order to get more information about Power Management for Kinetis MCUs:

http://cache.freescale.com/files/32bit/doc/app_note/AN4503.pdf

Hope this information will be useful for you.

Have a great day.

David

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