Samsung's wireless charging pad (model EP-PG9201)—which is/utilizes a technology commonly known as wireless power transfer—is advertised as being Qi (pronounced "chee") certified that allows for the charging of compatible Galaxy smartphones and other Qi-compatible devices.
This solidly-built charger is rather lightweight with a very nice style and an excellent fit-and-finish feel—I would expect nothing less from Samsung.
Samsung's Wireless Charger (EP-PG9201). Image courtesy of Amazon.
Oddly, I'm unable to find any specification which states how much power this pad is capable of transferring. It can be assumed, however, that the device will transfer no more than 9 W—this value is based on the label's input specification of 5.0 VDC at 2.0 A and assumes a system efficiency of 90%.
Label on bottom-side stating the input voltage and current specifications.
No External Screws
In an effort to save money on material and labor costs—or, perhaps, in a futile effort to prevent people (like me) from tearing open this device—Samsung designed this wireless charger without any external screws. I realized this fact only after removing the top- and bottom-side adhesive padding as well as the bottom-side label.
No external screws are used.
I used my fingers and hands to twist, pry, and pull, and then applying heat using my trusty heat gun followed by more prying and twisting—all with no luck. After that, I resorted to prying the enclosure open by using not one but two flathead screwdrivers—I actually put on my safety glasses because I didn't want to accidentally poke myself in the eye with the screwdrivers.
This charger seemed to be nearly impenetrable short of using a hammer or a Dremel, which I seriously considered using. Only after separating the two pieces did I see Samsung's concealed attaching mechanism: the top and bottom pieces twist-and-lock together. However, given the right tool (say a very-thin file) the locking mechanism can be released which would then allow the two pieces to unscrew, but still probably with some effort (see images below).
Four tabs and slots are used to secure the two pieces together with a twisting action.
The locking mechanism. The tab on the left can be depressed using the right tool, thus allowing the device to be unlocked. The enclosure can then be opened by untwisting the top and bottom pieces.
Internal Electrical Parts and Assemblies
This charging pad performs its wireless power transfer magic using a single PCB and one coilalbeit— a rather very large coil—which is typical for wireless charging devices. The image below shows how both the PCB and the coil are attached to each with a single plastic disc separating them.
The internal electrical subassemblies consist of a single PCB and a large coil.
Examining and Dissecting the PCB
The PCB is impressively simple, at least when referring to the few electrical components that it uses (see image below). And although the ICs are clearly marked, I was unable to locate datasheets for the voltage regulator and the "current flow devices," which I assume to be either high-speed diodes or FETs.
The major electrical components identified.
- Voltage regulator: IC marking: 9519 H451
- Current flow devices (qty 4): IC marking: AIW 7JAB
Removing the EMI Shielding Can
Since no processors were found anywhere else on the PCB, it makes sense that the IC underneath the shielding can (an EMI countermeasure) is the brain of this wireless charging system.
The IC that is located underneath the shielding can is clearly shown in the image below. This IC is manufactured by IDT with part marking of P9235, which is a transmitting controller for wireless power transfer applications of <3W made by IDT.
IC underneath the shielding can is the brain of the system.
Samsung's new wireless charging pad (the EP-PG9201) looks to be a simple yet well-designed and well-built wireless power transfer device. I personally don't own wireless power transfer devices (either transmitters or receivers), so I can't comment on how well this device works. I can say, however, that based on the maximum power transfer specifications (3W) of the IDT controller together with the listed input voltage and current specifications of this device (5V and 2A), this system looks to be quite inefficient (30%). Perhaps this low efficiency is on par with other similar wireless power transfer systems.
If you have experience with designing or analyzing wireless power devices, please let us know your experiences in the comments below.
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