Where/How to find useful power/current consumption documentation?

[Andy]

Hello,

I'm trying to do some power optimization in my project and I'm looking for information about current consumption of different peripherals. Unfortunately, the information I find is all over the place.

For example, if I wanted to check the power consumption of the UART peripheral I would go to the NRF52832 Product Specification and check the Electrical Specification of the UART peripheral. There I see that the run current @ 115200 bps is 55 uA. However, by looking at different threads here in the DevZone I see that the current consumption depends on many more factors other than baud rate, e.g. usage of flow control, EasyDMA, etc.

The current consumption of the UART peripheral, for what I can tell by reading these threads, is on the order of mA, not uA.

As I have power consumption questions about several peripherals, I ask about how to find out the information myself, rather than asking the questions specifically.

For example, I want to check the power consumption of the PWM peripheral. How would I go about that?

Thanks for your help!

[frankie_pham]

hi Andy,

About Nordic's document, you can find all here.

Your question about power current consumption, I found that in Nordic there is a keyword "power profile". There is a online power profiler here. I see that this power profiler only supports for radio power.

in my opinion, power consumption of a particular peripheral depends on many factors. Your GPIO output pin drives 1KOhm resistor is different from driving 500Ohm resistor about current consumption! So, it's hard to make sure that how much power a peripheral uses.  2 chapters in Product Specification are "power and clock management" and "power" may help you.

Best Regards!

Frankie

[Andy]

Hi Frankie,

Thanks for the link to the power profiler! I didn't know it. I know where to find the product specifications, but as I said I'm failing to find useful information there. I already checked those power chapters with no luck.

[Stian Røed Hafskjold]

Hi, unfortunately the peripheral currents are not fully documented in the product specification because there are too many factors involved.

In general the HF clock needs to be started and the DMA bus needs to be running when the peripherals are active. These two combined is about 1.2mA or 2mA for DCDC enabled or disabled respectively. For peripherals without DMA, the current depends on how much the CPU is working during the transactions.

[Stian Røed Hafskjold]

When I say "peripherals are active" I mean during the actual transaction. Just enabling the peripheral does not start the HF clock and DMA

[Andy]

Hi Stian, thanks for your reply! I have a question regarding the "activity" you mentioned. In the case of the PWM peripheral for example: From what you say I understand that it's enough to just stop the peripheral (nrfx_pwm_stop()) and I don't need to deinitialize it (nrfx_pwm_uninit()) in order to save power?