Valueline USB AC charger VLMP11955B

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Official specifications:

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I got it in a plastic bag.

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Measurements


Valueline%20USB%20AC%20charger%20VLMP11955B%20230V%20load%20sweep

This small adapter can deliver the rated current and a bit more (the overload protection looks fine).

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It works about the same on 120VAC

Valueline%20USB%20AC%20charger%20VLMP11955B%20230V%20load%20test

No problems running one hour at 1A.
The temperature photos below are taken between 30 minutes and 60 minutes into the one hour test.

Temp3418

M1: 64,6C, HS1: 78,8C
HS1 is the transformer.

Temp3419

M1: 54,9C, M2: 55,6C, HS1: 60,6C

Temp3420

M1: 57,4C, HS1: 64,8C
HS1 is the transformer.

Temp3421

M1: 61,3C, HS1: 67,5C


10ohm

At 0.5A the noise is 36mV rms and 384mVpp.

5ohm

At 1A the noise is 40mV rms and 317mVpp.

2.5ohm

At 2A the noise is 56mV rms and 410mVpp.


Tear down

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My vice and a mallet could open it.

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The plastic shield inside the box is used for isolation between mains and low volt side.

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At the mains input there is a fuse and a blue safety capacitor. Between the two capacitors is an inductor with shrink wrap around. The mains switcher transistor (Q1) is next to the transformer. The transformer has wires to the low volt side, where the rectifier diode is placed.

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The fuse (F1) is next to the mains input wire.

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Here the inductor between the two mains capacitors can be seen. One of the capacitors has shrink wrap on top of the plastic isolation.

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From this side the rectifier diode and the transformer can be seen.

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One of the capacitors is mounted on top of the usb connector and has heat shrink on its legs.

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This side contains a bridge rectifier (DB1) and the mains switcher controller. There is four resistor for coding the usb output (R15..R18).


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Safety distance looks good.

Testing with 2830 volt and 4242 volt between mains and low volt side, did not show any safety problems.



Conclusion

Generally this small charger looks well designed and with good performance, the noise is slightly high.



Notes

Charger was supplied by Pro backup (probackup.nl)

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