Electronics > Beginners

Is it ok to use two step downs in parallel?

(1/3) > >>

Sway07:
Hello,
my end goal is to power a RPI 400 and a old laptop screen with controller board from a single old laptop charger. Is it ok if I use the charger to convert mains into 19.5V and then two constant voltage step down modules wired in parallel to power the rpi and the screen? Here is a very crude but hopefully understandable paint drawing of what I mean.
Also I've measured the power draw of both the rpi and the screen. The rpi is drawing tops 2.3A ish at 5V and the screen is drawing 0.3A at 12V so I have plenty of head room in terms of power.
Thank you for any answers in advance.

tooki:
If you mean whether it’s OK to wire their inputs in parallel to the 19.5V, sure, absolutely fine.

Just don’t connect the outputs of two DC-DC converters in parallel (to increase the current) or in series (to achieve higher voltage), without checking the specs carefully first. Often that isn’t possible.

Sway07:

--- Quote from: tooki on October 14, 2021, 01:18:20 pm ---If you mean whether it’s OK to wire their inputs in parallel to the 19.5V, sure, absolutely fine.

--- End quote ---
Yes, this is exactly what I mean. Thank you!

Brumby:
You need to be careful if there is going to be a connection between the RPi and the screen, though!

This usually concerns the 0V reference point of the two - but there is the possibility that other connection issues may exist.  These mostly tend to be non-issues, but just be aware.

Sway07:

--- Quote from: Brumby on October 15, 2021, 01:16:19 am ---You need to be careful if there is going to be a connection between the RPi and the screen, though!

This usually concerns the 0V reference point of the two - but there is the possibility that other connection issues may exist.  These mostly tend to be non-issues, but just be aware.

--- End quote ---
Hmm, I tried it out and it seems to be working fine. Would this kinda problem be there from the moment I would power it on, or is it a thing that could down the line mess something up? My setup atm is I split the laptop adapter in to two wires with a wago connector. Those split wires go into the two step down modules, one for rpi, one for the screen. Obviously the outputs of the step downs go into the rpi or the screen respectively.

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version