Reduce startup power of Kinetis

carlostadeoorte — Thu, 06 Aug 2015 18:45:38 GMT

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

Re: Reduce startup power of Kinetis

david_diaz — Thu, 13 Aug 2015 20:13:27 GMT

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

Kinetis MicrocontrollersのトピックReduce startup power of Kinetis

Reduce startup power of Kinetis

Re: Reduce startup power of Kinetis