DC-DC Adjustable Step-down Module 5A 75W (CE07271)

Support Product Questions
21

I’m looking to step down a 12V power supply to power several servos under load (robotic arm). In doing so I’d need a max current drawn of about 8A which this module can’t quite handle. I was wondering if it’s possible to put two of these in parallel to be able to supply 10A in total without any issues?

Thanks!

1 Like
22

Hi Domantas
Running 2 supplies in parallels OK for bench work for a short time where the set up is 100% attended. Has to be done with a schottky diode in series with both supplies and the 2 supplies have to be balanced to share the load properly. Schottky diodes are suggested here due to the lower forward voltage drop. If 0.6 or 0.7V can be tolerated then “normal” diodes will do. With bench work power supplies would probably be adjustable so this voltage drop would be immaterial.

This arrangement with 2 supplies and diodes is normally used for redundancy in case of a failure. In this case either supply has to be capable of the full load.

The short answer to your question is not recommended. I wouldn’t do it anyway except for the redundancy requirement where a hot standby is required.
Cheers Bob

1 Like
23

Hi,

I’m hoping somebody can help me with adjusting the current limit of this buck converter.
I have it hooked up to a bench power supply at ~5Vdc, I adjust the output voltage of the module to ~3.5Vdc and then I try to adjust the output current limit however no matter how many times I turn the “cc” potentiometer my mutimeter always reads roughly 4A. That value does change by a few mA, but it seems random and not directly linked to any input from me. I have tried this with 3 of these modules and all behave similarly so I don’t think its faulty hardware.

Am I missing something?

24

Hi Cuan
Sounds like something wrong with your measurement set up. Can you post a sketch showing EXACTLY how you are trying to set this.
Cheers Bob
PS. Also what current limit are you trying to achieve and what is the current capability of your bench supply.

25

Hello everyone,

:white_check_mark: I can adjust my voltage to 12V without any problem.
:x: However, I am unable to achieve an output current lower than 2A.

Do you know why?

Here is my configuration:

Input:
Switching power supply MEAN WELL RS-25-12 (12V 2A)

Output:
Amperemeter NEOTEK XL830L set to “10A”

Thank you for your assistance.

26

Hi Julien
I think you might need a little more than 12V in to get 12V out.
Are you aware that the adjustment potentiometers are many turns (probably 20) from end to end. ou may not be turning it far enough and the 2A you are measuring could be the Max A the MeanWell supply can deliver.
Try turning the pot further. When you get to the end of its travel it can keep going with no damage and you will hear a slight “clicking” sound as it ratchets over the end.
Cheers Bob

27

Is the XL4015 DC-DC step Down converter able to convert like 5 or 6v to 12v.
As i have a Powerful 5v battery and i need to power a 12v Module. Would this work

28

Hi Marcus
No. You will need a step UP or step UP/Down converter.
Cheers Bob

29

Oh, But isnt that a step Down converter

30

Hi Marcus.
Yes. But you say you want to go from 5V to 12V. That is UP in my version of English.
cheers Bob

1 Like
31

Hi Guys,

I’m using your XL 4015 based step down module. Initially my input supply used 5x LiPo but I have had to increase that to 10x LiPo. Although the nominal voltage here is 36V, it is very likely that new batteries at startup will present as 40V, especially at the low startup load.

Your product page states an allowed input to up to 38V, the actual XL4015 datasheet states 36V as normal operating, whilst the abs. max. is 40V. As I am new to these modules, and don’t have a schematic to check, do you recon I’ll have a problem pushing the abs max for a bit? Or should I stick a diode or so in front just in case, although it impacts on overall efficiency?

Thanks,
mark

32

Hi Mark,

What sort of current are we talking here? The power lost in the diode is the voltage drop times the current, so that decides how wasteful it seems.

More importantly, how are you charging a 10S lipo! Most of the chargers I’ve seen only go up to 6S or 8S. Since you are stepping down anyway, could you go 9S or something to keep the step down happy?

Generally if you use a part at it’s absolute maximum voltage for even seconds you can expect damage.

33

Hi James,

Probably a couple of amps now, as I’m currently running 3x RP2040’s, an RPi4, camera, image processing and a bunch of other modules and servos. Will probably go all the way to 5A in the future.

I’m using two power tool battery packs, containing 5 x 16650 LiPo’s each, and using their brand chargers, so no issues with charging, all properly balanced, protected etc. (Printables)

That’s one reason why I can’t go to 9 cells. The other reason is that I need max volts for the main bus and motor drivers which I could push to 55V, hence the original change from 5 cells to 10 cells. (aka 18V → 36V).

Thanks for your advice James. As usual in electronics a comprise is needed, so I’ll stick in a diode or two in series with the convertor to keep it’s input below 38V. I’m probably looking at a 2V drop up to 5A = 10W loss + heat to move. My power packs are rated at about 150 Wh so about a 7% hit to efficiency. Worth it in this case for the 100% increase to power available to the motors.

Cheers,
mark

2 Likes
34

Hi James,

I think that there maybe a design problem with this board at the rated spec. There is a 78L05 regulator in an SOT-89 SMT package on the board. You can easily see that the inputs to this regulator are connected to the input power pins for the module. Now the XL4015 might have an abs max of 40V and recommended 36V but the absolute for the regulator is 30V with a recommended max of only 20V. Datasheet.

The online module specifications indicates the following.

Model: XL4015
Input Voltage Range: DC 4-38V

I believe that this is incorrect.

It may also explain why I’ve destroyed a few modules and connected hardware whilst running at 37V max. (10 cells - 3 diode drops)

mark

2 Likes
35

I found a solution for a 40V input - use these LM2596 based regulators instead.

20W Adjustable DC-DC Buck Converter with Digital Display
20W Adjustable DC-DC Buck Converter with Digital Display

Recommended input up to 40V with an abs max of 45V (LM2596) . Also, no current monitoring so the input and output negative terminals are shorted, making a common ground easier to setup.

Note there is also a LM2596S based device,

Adjustable Switching Power Supply Module IN 4V-35V OUT 1.5V-30V LM2596S Step-Down Converter
Adjustable Switching Power Supply Module IN 4V-35V OUT 1.5V-30V LM2596S Step-Down Converter

The Core Electronics specs say input voltage to 35V, however the LM2596S device is rated at 40V recommended and 45V abs max, same as the non-S variant. Datasheet. So in this case I think this specification is also incorrect, however I don’t have one to inspect nor do I have a circuit diagram to check.

mark

1 Like
36

Hey Mark,

Thanks for looking into the specs on that Step-Down Converter. I will pass this on to the rest of the team and get that page updated so that it displays the correct voltages.

Thanks again!
Sam

1 Like
37

So which trim is for which cunction and CC vs CV - using it to filter car 12v (13.2 - 14.8V) down to 9 v for Vin on Uno and 4 relay shield

38

Hi Linden
CC = Constant current or current limit.
CV = Constant voltage or voltage regulation.

I think you mean Function.
If you go back to the original post and Core product page the controls (CC & CV) are pointed out.
Be aware of the multi turn potentiometers. The subject was discussed in the first few posts.
Cheers Bob

1 Like
39

thanks bob …yes function …
need to click read more to get to 2nd image :<

40

Hi Linden
Go to the very first entry and click on the item description at the top or the “read more” link which will take you to the Core product page.
Cheers Bob

1 Like