Allmaybe LCD USB Wall charger EU2-ST

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Official specifications:
I got it directly from Allmaybe

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I got it in a white cardboard box.

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The box contained the charger, a warranty card and a instruction sheet.

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This charger has a display that shows volt, current and charged capacity.
The button is used to select between usb 1 and usb 2 and to reset the mAh counter, removing power will also reset the mAh counter.

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Measurements


Current

The display will first show current when it is above about 80mA and as can be seen from the table precision is about 0.04mA.
Voltage is correct when unloaded, when loaded there will always be some voltage drop in the connector and cable the readout cannot include.

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Usb #1 can deliver 2.7A before overload protection trips.

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Same with usb #2.

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But together I could draw 5A, i.e. there are individual port protection, HERE AT 120vac.

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And here at 230VAC

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And the charger can deliver 4.8A for one hour. The tick at 47 minutes is because I am handling it to get the IR photos below.
The temperature photos below are taken between 30 minutes and 60 minutes into the one hour test.

Temp4686

M1: 53,4C, M2: 40,9C, HS1: 70,3C
HS1 is the transformer.

Temp4687

M1: 43,0C, HS1: 48,8C

Temp4688

M1: 53,9C, HS1: 62,0C
Again HS1 is the transformer.

Temp4689

M1: 56,2C, HS1: 67,3C
Here HS1 is probably due to the rectifier.

Temp4690

HS1: 69,6C

10ohm

At 0.5A the noise is 24mV rms and 800mVpp.

5ohm

At 1A the noise is 18mV rms and 552mVpp.

2ohm

At 2.5A the noise is 25mV rms and 578mVpp

2ohm

At 5A the noise is 28mV rms and 576mVpp



Tear down

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I could not see a good place to squeeze or hit this charger (I would prefer to keep display intact), I went directly to cutting.

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At the mains input is a fuse (F1) and a inrush current limiter (RT1) followed by a X capacitor and a common mode coil (L1) with the safety capacitor (CY1) next to it. There is also a mains switcher transistor (Q3).
On the low volt side is a synchronous rectifier (U5 & Q11). The microcontroller (U4) with a connector to the display.
Between the two usb connectors is two power mos transistors (Q5 & Q6) to turn output on/off and some 0.015ohm resistors (R21 & R22) to measure the current across.

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On the first photo the usb connectors with the current sense resistors between are in front, together with the switch.
On the second photo the rectifier transistor (Q11) can be seen under the transformer and mains switcher (Q3).

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On the first picture the common mode coil is in front.
The second picture shows the connector for the display with the plug glued in (In a sealed box that is a good idea).

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On this side of the circuit board is the bridge rectifier (DB1) and the mains switcher controller (U1).
Below the usb connectors are the auto coding chips (U2 & U3).

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The display includes a backlight, the flat flex cable is also secured here.

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Safety distance looks fine.

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



Conclusion

This is a powerful two port charger with auto coding and display of current and capacity for each port. The charger also looks safe.



Notes

The usb charger was supplied by Allmaybe for a review.

Read more about how I test USB power supplies/charger