[SOLVED] XL4015 5A Step Down Module

[DianWardiana]

Hi,

I've used this step down to charge 12 VDC battery. The input is 15-19 VDC and i set output at 13.8 VDC 0.5 Amp.
My question is why i heard sound like "HMMMMMMM" in inductor of this step down?
I'm forget the specification the battery.

Regards,
Ian

 

[FvM]

There's no reference to a module in your post. Basic XL4015 step down controller doesn't provide constant current regulation, just 7A switch current limiting. Thus I wonder how you are setting current to 0.5 A. What's your input power supply?

 

[DianWardiana]

Hi,

here is the reference:
https://www.xcluma.com/xl4015-cc-cv-dc-dc-battery-charger

I just set the multiturn to set output voltage and current. I've used laptop adaptor for input power supply.

Regards,
Ian

 

[FvM]

Without a schematic, we can only guess about the circuit. I suspect they didn't manage to design stable constant current control.

 

[DianWardiana]

Hi,

I've got schematic from this site:
https://cxem.net/pitanie/5-325.php

Here is the schematic:


Regards,
Ian

 

[FvM]

Not bad at all. According to my trivial knowledge of Cyrillic, 10H could stand for 10 nF?

A problem might be that the current controller PI time constant changes when varying the current set point, not sure if it's unconditionally stable. There should be a series resistance between LM358 inverting input and set point pot.

 

[DianWardiana]

Hi,

As what i know from a translate is sure 10H is 10nF.
What do you mean by PI is Power Input? What size of resistor that i must add?

Regards,
Ian

 

[FvM]

Didn't talk about power input. PI stands for proportional-integral controller. **broken link removed**

I was guessing about a problem. You should first check if the converter is stable in voltage regulation or at higher constant current levels.

If the assumption turns out right, a 1 kOhm series resistor might achieve stability at lower current set points.

 

[DianWardiana]

Hi,

The converter is stable in higher constant current levels.
I didn't heard sound like "HMMMMMM" in inductor if i set the output current above 1.7 Amp.

Regards,
Ian

 

[FvM]

O.K., then this mod should work

 

[DianWardiana]

Hi,

I will try it tomorrow. I will notice about the result.
Thanks for your help.

Regards,
Ian