MP1584

[ivconic]

[ivconic]

Little puzzle... the real module without load draws 0.2mA and the fake module draws 45mA without load and the ceramic inductance heats up noticeably.
A careful inspection of the components reveals that they are not of the same value.
And with even more careful inspection, it can be noticed that some pins on the fake module are not soldered.
They are standing against a white silkscreen.
It is simply unbelievable that someone was stupid and careless enough to make fakes on such senseless and cheap components!? Or is it ignorance?

[Eddy71]

And how does the fake module behave if you solder the unsoldered pins of the chip?

[ivconic]

Interesting question!
I haven't tried it yet because I was in a hurry to work on a device that I have to finish by the deadline.
I put the "bad" module aside for later experiments. I will definitely try.

[Carl-NC]

I would try swapping the inductors. It sounds like the fake has a high-resistance inductor which will be less efficient and cause it to heat up.

[ivconic]

I have seen the MP1584 in various configurations.
But never with unconnected pins.
That's why I doubt that this is really the MP1584.
Anyway, I'll look into what it's about.
Right now I'm in a rush to finish a project, I'm running late and I'm afraid I'll blow my deadlines.
Specifically here I need the MP1584 to power the RP3A+. From a 12v battery.
Fortunately, among 5-6 fake modules, I found a couple of good ones that work properly.

[ivconic]

This is a schematic with a fixed voltage output.
However; I don't have the conditions to easily work with SMD, so I used the convenience of having a module with an adjustable output voltage.

[ivconic]

And how does the fake module behave if you solder the unsoldered pins of the chip?

So now; on the "fake" module pins 8. and 6. are not connected.
Bootstrap and switching frequency therefore.
I guess the module go wild if the switching frequency is not fixed with a resistor.
Furthermore... therefore the heathing and current draw.
Considering the current draw at RP3A+... i guess I would see a lot of white smoke, sooner or later, if I used the "fake" one.