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LED drivers from China, are they worth?

October 25th, 2018

I decided to upgrade the under cabin lighting in the kitchen. So, I got the LED lights but still I needed the LED driver too. If you browse on eBay then certainly you come with the LED drivers from China. And of course, the question are they worth? I took the risk and I chose the one which is shown below:

Chinese LED driver from eBay

I chose intentionally almost the most powerful LED driver, as it was declared 72W (6.3A 12V) (via eBay). The reason why I chose this one was quite simple – I was afraid that the specs are over-declared… As it appeared later, it cannot deliver so high currents but it might be still useful for someone who looks for lower specs. After waiting for a good month, I got the LED power supply and started investigate either it can really deliver 6.3A current 🙂

Hardware overview

The LED driver itself is driven by CR6850 chip, which circuit I found online:CR6850 LED driver circuit

Earlier shown power supply has 68uF 450V capacitor at its input (after the rectifier), which was quite good sign for such power (72W) SMPS. The power supply had also a soldered input filter. Hmm, great, let’s move on.

The power MOSFET, which was soldered on the board is STB6NK60ZFP (600V <1.2Ω 6A 30W). Ok, the first limitation is here. This part is marked as Q1 on the diagram.

The transformer is marked as EPQ26-25 in this diagram (for 12v 3A). In my bought unit, there are no any markings but after googling I found other photos of the same 72W LED  driver and it was marked as PQ2620. According to its datasheet:

PQ2620 LED driver

Well, it looks that we have a restriction again but this time with the transformer itself (max 20W). 30W as an example diagram is shown in the datasheet of the chip . Most likely, I got 20W LED driver instead of promised 72W, what is roughly 3x less than it supposed to be. Well but the measurements should reveal the true 😉

Performing the measurements

I still have an old 36 Ohms rheostat, which I use to load and test the power suppliers. So, I used as the load. I started the test with 4A loading, however the LED driver started to overheat (reaching above 60C degrees) already in 15 min. I stopped the experiment. What was interesting, the voltage & current were stable all the time. That suggests that bigger heat sinks are needed to handle such output currents. But at the same time, the transformer started to heat up too, which indicates as another limiting factor too.

Ok, I decreased the loading until 1A current. Here the LED driver did not start to overheat so hugely but it was reasonably warm (~35C). After playing around, I end up with loading the power supply with 1.5A current. Such loading remained not overloading the power supply and all parts were not too hot during 3 hours testing by producing ~44-46 C degrees.

The current which is used by 3x LED strip lights is only around 0.8A. In my case, it is roughly 2x less than the output current. So, nothing else was left except as to install the LED driver beneath the cabin to supply the power for the LED lights 🙂

In summary, I got pretty stable & not-overloading conditions to use this LED driver to supply max 1.5 Amps current but it is not providing the promised 6.3A as declared. That might be enough for some of you (via eBay). Otherwise, you have to look for an alternative which would deliver higher currents.