Teardown: Generic QC2.0 15W Charger (TCAU15U-050912)

Owing to the growing market-share of Qualcomm devices sporting Quick Charge 2.0 and 3.0 capabilities, the market for such devices has grown substantially. As part of reviewing some power banks with QC-capabilities, it would not be possible to assess their ability without having a QC charger myself.

Because of both being in a hurry and needing something cheap, back in May 2016, I purchased a generic QC2.0 charger for AU$10.22 just to try it out. At the time, none of my phones were QC capable, and it was really only to test the Anker PowerCore 10050+ power bank. While I have used it just a handful of times to test power banks, I had my doubts as to the quality of the unit, so I decided to give it a teardown.

The Unit

The unit originally came with two blade pins configured for US operation. With a quick modification enabled by a set of pliers, they now fit into an AU socket. Not recommended, but works in a pinch if you’re desperate. The outside of the unit has rounded corners and a tapered design, with a matte white finish and “generically” shows the Qualcomm Quick Charge 2.0 logo.

The opposite side has a single USB port, although this one did feel a little loose.

The bottom side has a list of specifications, with a model number of TCAU15U-050912. The only thing I could find was an “Itian Premium Design Quick Charge 2.0 15W Wall Charger”, with no clue as to who actually makes it. It claims an input of 0.8A which is quite high – maybe it’s got a poor power factor. It is capable of 5V, 9V and 12V DC as required by QC 2.0, and offers 15W maximum output, rather than the more customary 18W. The currents are not listed, but “assuming” 15W is 15W, that’s 3A at 5V (I doubt it), 1.67A at 9V (plausible) and 1.25A at 12V (slightly anemic). It claims an efficiency level mark of V, which is possible I suppose. The date code is Week 40 of 2015. It claims to be FCC approved (doubt it), double-insulated (it passed an insulation resistance test), and for use indoors. Interestingly, the pin-out makes no mention of D+ and D- which are used to negotiate QC2.0.

Given its already dubious credentials of low price and strange specs, I wouldn’t be leaving this one plugged in all the time, or trusting it with a precious phone. I can’t even be bothered to test it electrically for standby power or efficiency … partly because it does get a little warm in use, but also smells a bit like burning electronics. It hasn’t failed though, which is good …

Teardown

As the unit features no screw fasteners, opening the unit proved to be a semi-destructive act. This involved securing the power prong pins in a vice, and then slowly applying lateral pressure from each side until the end-plate removed from the body.

In my case, this resulted in a slight crack to the front facing plastic piece, but also the snapping of a fusible resistor leg as it was adhered to the front plate and mechanically separated upon opening. No matter, a dab of solder and it was repaired. Interestingly, the pins are moulded into the plastic and end as “stubs”. This goes into a matching tapered loop receptacle that protrudes upwards from the board that makes contact with the pins. I suppose this avoids having to solder wires, and allows for an easy “push and glue” fit of any region plug you might need. The loop receptacles do have some sign of corrosion, and the internals do smell a little bit of capacitor fluid.

The board is easily extracted from the board as it is guided by rails. The unit is a cost-optimized design on a single-sided PCB with silkscreening. The MOV used for surge protection is removed, and is the NTC for thermal feedback. However, the construction doesn’t appear all too shabby, with the exception of the cheap flimsy USB receptacle that has quite a bit of play and doesn’t seem quite “tight” enough with a weak outer shell.

Looking from the top, the responsible company is TDSEN, with a website at www.tdspowers.com that redirects to www.tdsen.com. This product is no longer within their catalogue, it seems. There are really not many components, but at least we see that the design incorporates opto-isolated feedback, a primary side inductor and proper Y-capacitor is used for interference suppression. Disasters are averted with a fusible resistor also acting as an in-rush limiter. There is a transistor for switching on the primary side, but there is no heatsink.

The main let-down so far is the downright random capacitors which come from Yihcon, y.u.g and CapXon. Of the three names, only the latter is known, and is not associated with positivity. However, that being said, the CapXon cap is an output capacitor that has been specified as a solid electrolytic, so it should have a better lifetime. A quick in-circuit measure of all the capacitors appeared to show that they still are in spec despite the smell and heat.

Instead, a decent amount of smell was emanating from the transformer itself, which is probably made by a company with initials HDY. It may be due to hot operation and outgassing of insulating plastics, however, while it looks decent from the outside, it’s almost impossible to determine the insulation separation without unwinding it and destroying it.

The underside of the board has a smattering of surface mount components. The bridge rectifier, a control IC, a 6-pin SMD marked 4N12 and a MOSFET seem to make up the majority of the major components. There is a nice isolating boundary on the PCB, complete with anti-tracking slot to ensure primary to secondary isolation for user safety.

I have no idea what the markings on the chip are supposed to say.

I’m not sure this chip is the N-channel MOSFET it claims to be – it may be working as an active synchronous rectifier, but I didn’t take the time to analyze it. The mounting is very strange.

Conclusion

It is a cheap charger, but it doesn’t look too nasty now that I’ve seen inside. While it seems to be very much a cost-optimized design with as few components as possible, the PCB appears to be laid out in a good manner with clear isolation between primary and secondary. Most of the components don’t look too bad, with the exception of the primary side capacitors. The controller is still a mystery, but the unit does work. The other downside is the flimsy USB output connector that seems to be high resistance with the cables I have.

I wouldn’t, however, recommend this unit for regular use to charge a precious phone – why risk an expensive phone to a AU$10 charger? Besides, its 15W rating seems to imply that it doesn’t deliver the expected 18W-24W that a proper QC2.0 charger would deliver, and it does smell bad when in use, suggesting that something is getting quite hot.

About lui_gough

I’m a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!

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