AOKoda 7-27V to QC3.0

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Official specifications: I got it from a Banggood.com

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I got this charger in a plastic bag

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The letters: LV, VI, VO, IO, QC is markings for the 5 leds on the circuit board, but they do not align (sequence is correct).
They mean: Low voltage, Voltage input, Voltage output, Current output QuickCharge
During normal use the display will change between (LV when using LiIon), VI, VO, IO, when the button is held down it is possible to adjust LV if input is DC, with "BAT" input the low voltage is selected automatically to match a LiIon pack.

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Vin, Vout and Iout


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Measurements

For all my test I uses a low voltage limit of 6.8V, except where otherwise noted.

Display

A check of display precision, it will say it is fairly good. The red line was done right after the 1 hour 5V 3A test where the device was very hot.



5 volt output

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The minimum input voltage can only be used for 5V output and here it can deliver slightly above 3A before it starts switching off/on.

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Higher input voltage increased the maximum output to 3.5A and reduces the efficiency a bit.

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At 27V the drop in efficiency is very obvious, it is probably due to the linear regulator supplying the display.

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The output turns off at about 6.8V as selected, but there is a fallout at 10.8V.
I did check this fallout a bit more later on, but it did not show up when I just regulated the voltage around 10.8V

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It is the same at 3A

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Using the BAT protection scheme means the device assumes 6s LiIon battery pack when I start with 27V and it will turn off at 22.2V.
The battery draw do not drop to 0, only to about 17mA, this means it is a good idea to disconnect the battery.

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This test is at 5V and 3A, i.e. maximal QC2 output. This is the current where the effect loss in the device is close to maximum and just at the edge of device shutting down. When the device got hot it started to shut down for short periods. At 47 minutes I turned it around to take a IR photo and that gave some fresh air to the chip and cooled it down a bit.
The 12V section also contains a load test.

Temp5355

M1: 128.7C, HS1: 135.0C
The inductor is fairly hot.

Temp5356

M1: 140.3C, HS1: 148.7C
The buck converter is very hot and the rectifier diode is close behind at this current level.
It is interesting to see the 0ohm resistor is slightly hot, there must be some resistance in it.



9 volt output

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QC can deliver 9V output with 12V input.

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With 27V input the efficiency goes down at lower loads.

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9V can be maintained down to about 11V with a 2A load, it is the same voltage as the fallout is at on 5V.



12 volt output

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At 18V input the 12V Quick Charge can deliver nearly 3A (It is only rated for 1.5A)

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It is about the same with 27V input voltage.

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The charger can maintain 12V output down to about 14V input with 1A load. The spikes going up at 11V is probably the QC trigger trying to reengage QC 12V.

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Using a 2A load the input voltage must be closer to 15V

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Here I raised the input protection to 20V and the output is turned off at 20V.

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But the device is using a little bit of current after it turns off. It is around 20mA.

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There was no problem running 1 hour with full 12V QC output. I used 15V for input.
The temperature photos below are taken between 30 minutes and 60 minutes into the one hour test.

Temp5338

M1: 38.6C, M2: 35.0C, HS1: 45.6C
The hot spot here is probably the inductor.

Temp5339
HS1: 43.7C
On this side it may be a combination of inductor, buck converter and rectifier diode.

Temp5340

M1: 40.1C, M2: 37.6C, HS1: 44.2C

Temp5341

HS1: 46.6C

Temp5342

HS1: 45.3C

10ohmVI27V

The noise at 0.5A is 23mV rms and 220mVpp, all noise charts are made with 27V input, because that gave the most noise.

5ohmVI27V

The noise at 1A is 22mV rms and 189mVpp

2ohmVI27V

The noise at 2.5A is 22mV rms and 168mVpp.

10ohmQC9VVI27V

The noise at 9V and 0.9A is 39mV rms and 280mVpp.

10ohmQC12VVI27V

The noise at 12V and 1.2A is 50mV rms and 280mVpp.



Tear down

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There is no screws or clips, I could just pull it apart.

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On this side is the display, a couple of leds (5), a inductor and a output capacitor.

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At the input is a buck regulator (CXW8505) used for output voltage and it uses a SS34 as rectifier diode. The processor and display need a stable voltage and uses a linear regulator (7550: 5V 100mA with a max. input of 24V). The processor (STM8S003F3P6 8kB flash, 1kB ram, 5*10bit ADC) handles the display and the voltage limit. The actual QC is done my a 6 pin chip (FT4) and there is a OpAmp (A63A: LM321) next to it, it is probably measuring the current across some resistance, but I do not see a resistor for it (Maybe they use the 0ohm resistor).

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Being a low volt device there is no need to test with high voltages.



Conclusion

A useful device for people that uses LiIon battery packs, it is easy to carry around and it can make them into QC3 power banks. I can, of course, also be used from other power sources.
The 3A rating for 5V QC is a bit optimistic, but then very few devices uses 3A and I do not believe it is much of a problem. It supports a lot of fast charging protocols, this means most phones will charge fairly fast on it.




Notes

The usb charger was supplied by a Banggood.com for a review.

Index of all tested USB power supplies/chargers
Read more about how I test USB power supplies/charger