Determining SBC power requirements

SITCore
#1

How can one determine the power requirements in using an SBC.

And there is a note in the documentation that “The ‘Running’ power consumption totals include all other on board components, such as WiFi & Display.” But those values do not likely include port peripherals such as the power consumption of a port configured as an input pull up. And this is exactly what I would like to know.

Specifically Im trying to understand what reasonable expectation are. So say i wanted to drive each of the gpio on my PICO as an input pull up, with no information regarding what the internal pull up resistor value is or what the expected current draw for each would be, I am unable to reasonably determine how many gpio input pull up ports I might expect to actually be able to configure before problems might arise.

I find the datasheet for the onboard voltage regulator stating min 600mA current capacity.
But what is the port pull up resistor value/internal current draw?
I figure with these 2 values, i can figure out what can be expected.

#2

Searching this site I found STI core SC13 processors uses the Arm Cortex M4 as it’s core? Would this then mean the peripheral specifications are of the same device?

I found typical pull up resistor value published as 40k ohms, can I assume this relevant here? That might explain individual port specs, but then I was unable to find data on total processor sink current which could also then be limiting.

So what would be the total device sink limitation is applicable?

#3

I am not sure what the problem might be. I guess I never thought of current needed for pull ups to be anything significant…unless you are developing an extreme low power application and need to count every uA.

If you need deep details then you can check the STM32L452 datasheet.

#4

More than the internal resistance I ultimately needed to determine current usage. Problems arise for instance when after selecting peripheral components and laying out boards, you find a problem in the rare occasion that many gpio are attempting to source or sink current in excess of what the processor can handle…

I was able to find pertinent info on the datasheet for said processor.

Total output current sunk by sum of all I/Os and control 100ma

Truth be told I found it a rather low sum.
I currently need to source or sink 10ma per port and will need to reconsider things.

Thanks for the info.

#5

Can’t you use external transistors or mosfet for the sinking?

#6

Surely external hardware will be required. At least now the limitation is known.

Knowing the relevant base device and datasheet it’s very helpful.