Hi,
This question is for VIM3.
I see the 5V_1, 5V_2 and 3V3_1, 3V3_2 pins exposed on the GPIO Header.
Net names are VCC5V, VCC3.3V and VSYS_3V3.
If I want to power an external pcb from these power pins, can you tell me its milliamp safe capacity for both 5V and 3.3V pins ?
Thank you.
Simon
Hi, it depends on what external device, in general, the more current, the better, but in general, the nominal consumption of vim3 is up to 12v 2A
Let’s say the Khadas is powered from USB-C with 12V / 2A.
The 5V and 3.3V are coming from dc regulators with a maximum capacity. For example, can I still power a 3.3V / 500mA PCB from the 3.3V pin ? Does the 5V pin has more capacity and better to use with a 3.3V DC regulator on my additional PCB ?
Thank you
First you need to find out how demanding your additional payment is (how much it needs to fully receive power supply)
Thank you. What I am asking is the other way around. I am designing a PCB that will connect on the VIM3 GPIO Header. I want to know how much power is available there. Depending on the max capacity, I will know if I need to use an external power source or not.
If you use a proprietary Khadas power supply, then you can navigate according to its scheme, respectively
Well, let’s use the 3.3V as an example. Correct me if anything here is wrong, but it is not coming from that 12v power supply. There is a DC regulator on the VIM3 Board that has a 3.3V output with a maximum capacity, let’s say 900mA. Even if the Khadas power supply is able to deliver a lot more. Then there are components on the VIM3 board that are powered from that 3.3v source which sums up to a theorical maximum milliamp usage, let’s say 400mA. In that example, 500mA would still be available to power up my board.
Excuse me, of course, but I think you yourself answered your own question. It won’t be enough!
If you have a multimeter, you can measure the current yourself
The first one is NB680GD with 5A. Then I see WPM3401 (3A), WL2803E18 (LDO), MP8756 (6A), SY80210DEC (2A) * 3, and MP8756 6A.
I think 3V3 pin is linked to the output of WPM3401 (3A). If it’s the case, it’s powering eMCC, LCD, Audio, and others connectors. Yes with a multimeter, I can unsolder the DC-DC regulator and make measurement. It surprise me that it’s not already known information.
Thank you. I will find it.
Hello, You just want to know the maximum current that can be safely supplied by the GPIO 3.3v and 5v pins?
I am not sure on the VIM3, someone from Khadas Team will be able to answer that for you.
Until you get an answer, I would limit 5v to 500mA.
@Gouwa @goenjoy or other Khadas staff will likely have the answer.
Hi, yes, he needs information about the output current from these pins for an additional board, do you have such information?
I don’t think I have the info. Seems it was discussed before but I’ve yet to find it. Even then, could have been a different VIM. Still looking.
Thank you, I remember that you have enough diagrams, and I thought that probably you could know such information 
@SimonAmpleman It is 500 mAH for the VCC5V,
VCC3.3V and VSYS_3v3 each,
should be around 500mAH maximum
(image not included, as there are multiple references to the powerails…)
you can observe that from the schematics if you want to know more info about it… (Keywords: VSYS_3v3,VCC3.3V)
I recommend trying to keep 3.3v power consumption minimum(use no more than 500mAH) as very critical components of the CPU and system are along that path…
Sigh…
A electrical device will only consume the required amount of current it requires and nothing more.
Note that there are physical limitations as to how much current the PCB traces can withstand…
That is not nominal, 12v is just the maximum the USB-C port can handle…
a multimeter cannot measure maximum current output, It can only measure instantaneous and peak current draw.
these are fundamental things in power electronics or even basic electrical systems…
don’t blart random values, I hope you can understand now
Are you feeling bad?
re-read what I wrote, then we will discuss, probably
for you…,
I am well versed with power electronics, I know what I just said… 
I know that you are learning from Google 
Why on earth would I do that ?
If anyone can search answers from google themselves, why would they ask questions here ? 
