3

I'm trying to use the 3.3V rail to power up 10 LED (20mA/LED).

I read that the raspberryPi could supply until 1A through this 3.3V rail, that's a lot more than needed when all the LEDs are powered on.

When I'm using the regular power supply of raspberry (2.5A, 5V) through usb, I somehow don't get enough current to light my LEDs: enter image description here

When I use my laboratory power supply with the same set up (2.5A, 5V) to power up the raspberry through usb, the leds light up correctly : enter image description here

I also tried with a phone power supply with the same set up again (2.5A, 5V) and it didn't work.enter image description here

In the end, I tried with an industrial power supply converter (230V to 5V, 3A) and it worked correctly : enter image description here

It seems that some of my power supplies don't deliver enough current.

I don't understand why there are such differences in behaviour, the power supplies are supposed to be the same technically.

Is there anything I could have missed about this 3.3V raspberryPi output ?

What could I do to check this power supplies ?

Improve this question
2
  • 2
    Some models of Pi can supply more than an amp on the 3V3 power rail. Which model Pi are you using? Also let's see photos of a setup you are using which does not work.
    – joan
    Sep 17, 2019 at 15:46
  • I'm using thePi 3 model B+, I just added the pictures of the power supplies I used
    – A.Girafe
    Sep 25, 2019 at 12:57

1 Answer 1

Reset to default
2

the power supplies are supposed to be the same technically

No, they simply have the same or similar maximum ratings.

A phone charger is intended for charging batteries. A supply intended for powering live electronics has to meet instantaneous demands and an arbitrarily fluctuating load that a charger does not -- and it might, in fact, it might be detrimental for a charger to do so.

If we consider the role of the phone charger less demanding, then this is sort of a quality issue: Which do you think needs to perform in a more demanding environment, your lab bench supply or your phone charger? I bet the former cost a bit more too. On the other hand, using that bench supply to just to charge your phone might be considered awkward because the bench supply is heftier and a waste of money since all you needed was a phone charger.

But the Pi is not a battery powered device which needs recharging.

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.