Teardown Tuesday: Samsung Wireless Charger (EP-PG9201)

December 05, 2017 by Nick Davis

In this teardown, we tear open Samsung's wireless charger to examine its internal components.

In this teardown, we tear open Samsung's wireless charger to examine its internal components.

Visual Inspection

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.


Next Teardown: Solar-Powered Water Fountain

  • sjgallagher2 December 05, 2017

    Is it just me or does that transmitting controller look off center…

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      ndavis17 December 07, 2017
      Hello sjgallagher2, Good eye! Yes, the controller is indeed crooked a bit. I’m confident that this IC placement would fail IPC Class 3 standards, but it may, maybe, pass Class 1 or 2 inspection. With that said, I haven’t seen any documentation from Samsung stating that the assembly has passed, or is designed to meet, any IPC standards. FYI. Below is a link to one of our IPC standard articles: Thanks for your question. -Nick
      Like. Reply
  • M
    Mocito December 05, 2017

    Regulator ISL9519 from intersil?

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      ndavis17 December 05, 2017
      Hello Mocito, Good question. I originally thought the same based on the description of the ISL9519 datasheet. However, the ISL9519 IC is advertised as being a 28-pin device while the IC in question on the Samsung PCB is only 8-pins. Therefore, I don't believe the ISL9519 is the correct part. Thanks for asking the question. -Nick
      Like. Reply
  • dante_clericuzzio December 05, 2017

    Wireless always less efficient than cable…and secondly whats the point when you have to connect the wireless charger to power source and charge on it…like buy a device to double the trouble…why not just stick the charger cable straight to the phone itself.

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      ndavis17 December 07, 2017
      Hello dante_clericuzzio, Hopefully, eventually, efficiency levels will increase with wireless charging technology. If not, and if 30% efficiency is the norm, then I doubt wireless power transfer will become overly popular, especially with the ever-mounting pressure from environmental and legislative groups to reduce energy consumption and increase energy efficiencies. To your 2nd point. If this technology could be integrated into a couch, kitchen table/counter, an automobile's center console, etc., where a user could simply lay down their phone or tablet and it would charge, then I could see the benefits of using this tech. However, I'm personally not a current user of wireless power transfer, and am simply happy with plugging in my smart phone. Thanks for your comments!
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      neilwarnock December 12, 2017
      One advantage I can see is that there is no need to keep plugging flimsy micro USB connectors in and out of your device. In my experience these are really unreliable and often the first thing to fail.
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    philba December 06, 2017

    That PCB looks like an exercise in thermal vias.  But there are also a lot of the vias a long way from any component (5 via clusters everywhere). Is this related to induced ground plane eddy currents from the charging coil?

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      ndavis17 December 07, 2017
      Hello philba, The PCB is a multi-layer board; it definitely has two internal layers but may have four or more. The top and bottom layers are mostly ground (i.e. ground planes), and the vias appear to be used, primarily, for stitching internal layers to external layers, and for normal PCB trace routing and layout. Some of the via groups look to be randomly placed, but there may be a strategy here, like avoiding internal traces. Also, the designer's layout tool/software may not have the "flood planes using vias" functionality (or something similar), which would result in manual via placement...which would be time consuming. Thanks for your comment and question. -Nick
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  • H
    habeebkambrath December 07, 2017

    dear admin sir/moderators

    i can share this on our forum with ur and writer credit?

    it will help us alot

    Like. Reply
  • A
    aw2xcd December 08, 2017

    Are those 4 square white SMD parts capacitors required for the LC circuit?

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      ndavis17 December 11, 2017
      Hello aw2xcd, Those four caps are part of the LC resonance tank. IDT has a wireless power transfer demo board with various supporting documents (layout guide, datasheet, etc). You may want to read these documents for information that IDT has provided regarding similar caps on their own design. The p/n for IDT's demo board is P9038-R-EVK: Hope this is helpful. -Nick
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