Power Supply for Zynthian


#1

Hi @Hampelschwein!
To set up power supply like this you need:

  • 5V 3A DC-DC step-down converter (like this);
  • 3A Schottky rectifier diode (SR360, 1N5822, etc.);
  • DC jack socket;
  • Micro USB male plug (5 pin);
  • Voltmeter (for checking and adjustments).

First, solder all the components like this:

At this step, it is a good idea to put the diode into heatshrink tube to avoid short circuit.

Next, double-check the connections and make sure that the converter’s “OUT+” pad is soldered to pin 1 of micro usb plug, and “OUT-” pad is soldered to pin 5.

You must check the output voltage before connecting this power supply to Raspberry Pi.

To do that, connect your external DC power supply to the DC jack and check the voltage at step-down converter’s output pads, it should be 5.0-5.3V:
dc-dc
If the output voltage is different, you need to adjust it by rotating the trimmer potentiometer:
dc-2
Safe voltage range is 5.0-5.3V.

For the best results, gold plated Micro USB plug is recommended!


Success Cases
#2

Hey thank you so much for the description!! I will work on this a s soon I can :smiley: and let you know about the result


#3

and then the optimal dc power supply would output anything between 4,75 V to 23 V and 3 A and + in the center?


#4

Can you recommend to put the dc power supply inside the zynthian case or could that cause problems if its too close to the raspberry?


#5

DC power supply should be greater than 6V, because step-down converter’s output voltage is always lower than input voltage.
Using 9-12V DC power supply is optimal. The amperes rating could be then lower than 3A. Higher the input voltage, less amperes are required - that’s the way step-down converter works :nerd_face:
So, I use universal 12V 1A DC power supply with no problem.

Yes.


#6

It should be kept away from audio jacks and cables, that’s the only recommendation I could give :slight_smile:

Inside my zynthian case, I put the step-down converter and the dc jack in the corners opposite to the audio jack:


#7

This is a very clear description. I built a very similar circuit into my Zynthian & it’s been working fine. I did notice a couple of things when building mine…

  • Make sure that your ‘wall wart’ power supply has a DC output. I’ve got a whole box of assorted power supplies from various gadgets & tested them all with a scope & voltmeter. Many of them have unregulated outputs with huge ripple. So look carefully at the rating label!

  • There are a couple of common sizes for cylindrical DC power connectors (2.1 & 2.5 mm). The socket that you mount on your Zynthian has to match the cable.

-Andy


#8

i finally did it, works fine! Thanks again!


#9

@Hampelschwein
Which stepdown converter did you buy? Chinese import or did you find sth at Reichels/Conrad?


#10

i bought this one http://www.ebay.de/itm/182705507415


#11

Thanks, that was really helpful. Now I don’t have to worry about issues caused by a unstable USB-charger. :slight_smile: