How to find genuine lm2596 boards?

[tecneeq]

I want to hook up a RPi (5V) to the 24v power supply on my 3D Printer. Also i have a 12v silent fan that uses 12v, i would use it to replave the tiny and loud 24v one that cools the mainboard.

It seems getting a stepdown converter based on the lm2596 chip is the way to go, except that they are all ... fake.

Do you just don't give a hoot, and use the fakes, or do you have a reliable source that i could tap into (from Germany) to buy the real ones?
 

Say i would buy this part, from Reichelt, which is, i think, a reputable source, would i have to expect this to be fake?
https://www.reichelt.de/entwicklerboards-spannungsregler-dc-dc-wandler-lm2596-debo-dcdc-down-2-p282579.html

[Doctorandus_P]

I think Adafruit has their own SMT assembly line, but I don't know where they source their parts.
I'd say give it a stress test with a DC load and then live with it.

One thing you can do is to add a fuse and a crowbar as overvoltage protection.

I was looking at monochrome graphical LCD's recently. You can choose between an EUR4 display from Ali, or an EUR30 display sourced locally, which is probably also manufactured in china, but probably from a factory with higher quality standards. It does not seem much of a choice. Maybe those higher prices are affordable for industial applications, but for diy or if you want to sell kits for hobbyists and similar consumers there is no choice. It's either chinese stuff or you price yourself out of the market.

[radiolistener]

If you can do tests, you can check it's noise frequency. As I know, fake items working at twice lower frequency.

Original one works with 150 kHz noise.
I bought LM2596 module on aliexpress and it has noise frequency 60-80 kHz, I think this is a fake chip.

[Ian.M]

Say i would buy this part, from Reichelt, which is, i think, a reputable source, would i have to expect this to be fake?
https://www.reichelt.de/entwicklerboards-spannungsregler-dc-dc-wandler-lm2596-debo-dcdc-down-2-p282579.html

As they sell the chip for more than the board:
https://www.reichelt.de/abwaerts-schaltregler-adj-4-5--40-v-5-0-v-3-a-to-263-5-lm-2596-s-5-0-p187637.html
you can bet the one on the board is fake.

The problem is the fakes run at ~52KHz vs 150KHz for the genuine ones, so need three times higher value inductor and capacitors to deliver comparable performance, but the parts fitted to the fake modules invariably have values appropriate for the genuine chip.  This means they cant deliver more than 1/3 the nominal current, and not for long.  Using them over 500mA continuous is a risky gamble, so definately not suitable for the Pi.

[Doctorandus_P]

I can confirm that at least some of the "fakes" run at a much lower frequency.
I once bought a batch of "low ripple" versions, with two inductors, so they have an extra output filter.
These also run at a much lower frequency, with an inductor with not enough inductance.
And with that output filter the ripple was near what was expected of a real chip.

Maybe one of those XL4015 or clone boads are better if you need more current.

I think I do like the mini  MP1584 buck converters. These run at much higher frequency.

But in general I use them for non critical applications and for much lower currents then stated.

But do test them with a DC load. If they go poof, they were no good, if they keep working without getting to hot, you have a decent chance they also keep  working for a longer period.