Samsung ETA-U90UWE (Probably fake)


This is a 5V 2A rated usb power supply/charger for use in UK.

Official specifications: The charger was bought from Fasttech, but they do not sell it anymore.


I got it in an envelope, not an original Samsung box and no manual.

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Data matrix code: GH44-02437B RT4G109vS



Output voltage is stable and the charger has an efficiency just below 80%


One hour with 2A load is no problem.
The temperature photos below are taken between 30 minutes and 60 minutes into the 1 hour test.


M1: 60,7C, M2: 48,2C, HS1: 62,0C
M1 is the rectifier diode. HS1 might be the transformer.


M1: 46,4C, M2: 47,8C, HS1: 54,9C


M1: 45,4C, M2: 39,9C, HS1: 64,9C
HS1 is the rectifier diode.


M1: 49,0C, M2: 44,3C, HS1: 51,2C


M1: 45,4C, M2: 40,7C, HS1: 53,6C
HS1 is the transformer.


At 0.5A the is 33mV rms and 660mVpp.


At 1A the noise is 37mV rms and 560mVpp.


At 2A the noise is 59mV rms and 950mVpp.

Tear down


Some pressure on the charger and the lid pops off.


Notice the plastic shield between the usb connector and the transformer, this is used to increase the distance between mains and low voltage side.


The charger looks very simple from the top. On the input there is a fusible resistor (Marked F1), switcher transistor and a safety capacitor to the usb output.
The output side has optical feedback and the large capacitor, nothing else.


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Notice the part between the two capacitors, it is marked L1 and is a inductor to reduce noise.


On this picture the safety capacitor is very obvious.


There is more parts here, the diodes D1, D3, D4 and D5 is probably the input bridge rectifier. The chip below all the white stuff is the mains switcher IC.
The diode D7 is the rectifier diode.

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The two white parts with pins goes through the box and is used for mains connection.


The safety distance between mains and low voltage side is on the low side, it is only 4mm.

The charger passed an isolation test with 2500 volt, but failed a 5000 volt test, this makes the charger acceptable for 110VAC usage, but doubtful for 230VAC usage. With a 230VAC plug in the charger it is not acceptable.


The construction of this charger looks like it is the genuine article, but because it failed the 5000 volt test and due to the short isolation distance I doubt it. The output coding is also suspicious, is this a new Samsung code?
The output is a bit high on noise but the general performance is fine.


The 5000 volt test voltage is higher than the requirement, this might be the reason it failed that test. The correct voltage is 4200 volt, but my tester does not support that.

Read more about how I test USB power supplies/charger