Last year, Xiaomi launched the smallest 65W GaN charger, which totally changed the industry.
After a year, Xiaomi has launched a new generation of 65W GaN charger,
adopts USB-A and USB-C, foldable pin design. We have got this charger.
So, let’s unbox it right now. The packaging is still the familiar Xiaomi style.
And this is the information behind the box. This model is AD652G.
Maximum output of USB-A is 18W. Maximum output of USB-C is 65W.
Maximum output for dual ports will be 18W + 45W.
Open the box. There are a charger, cable and manual.
The length of the cable is about 1.5 meters (1.64 yds).
Support 5A high current and 100W fast charging.
Now, look at the charger. Look like a white lipstick.
The front is USB-C and USB-A output. The back is the folding pin.
Let’s look at the specification at the bottom.
It’s almost the same as the back of the box we saw.
Let’s measure the size and weight. The size is 71*31*31mm (2.8* 1.22*1.22 inches).
The weight is 104g (3.67 oz). Compare with the previous generation.
The thickness of those two is the same, but the new model is a little bit longer.
The folding pins and USB-A port will take up more space, obviously.
Take out the Apple 61W charger for comparison.
And then, use ChargeLAB POWER-Z KT002 to test the protocol.
USB-A supports Apple 2.4A, QC2.0 and QC3.0 fast charging protocols.
USB-C supports additional AFC protocol. The PDO message shows USB-C supports 5V, 9V, 12V,
15V, 20V, five fixed voltage gears and 5-11V5A, 5-20V3.25A, two sets of PPS voltage gears.
This charger uses mainstream GaN fast charging high-frequency QR power architecture,
which can effectively reduce the size of the transformer, to provide the multi-port output.
How does it inside look like? Let’s go, tear it down.
Mr. Hammer took today off. We got a pan instead.
Ok, we have opened the charger. Take out the PCB module.
It is covered with a layer of copper heat sink. The input end is covered with a plastic cover.
The contact adopts ENIG (Electroless nickel immersion gold) design.
There are also heat sinks and isolation plates on the back of the motherboard.
The low-voltage side is also wrapped with a layer of insulating tape to insulate.
Remove the outer heat sink, isolation plate and thermal pad.
The input terminal inside is also covered with a plastic case.
The big one in the middle is an electrolytic capacitor for high voltage filter.
There is also a layer of insulating tape on the outside.
And an insulating rubber sleeve on the top, which is used for insulating the secondary output board.
A lot of glue is filled around the components for reinforcement
and heat dissipation. Remove the plastic cover.
There are also two small boards welded vertically at the input end.
The AC input filter and rectifier circuit are on the small board.
Xiaomi welded components through multiple small boards,
to increase the space utilization of the charger and achieve the high-density design.
The motherboard is hollowed out at the position of transformer,
which can also increase space utilization.
On this side, you can see the master control chip of switching power supply, optocoupler,
Y-capacitor, GaN power chip and synchronous buck-boost converters for USB-A output.
Remove two small boards. One of them has fuse,
safety X capacitor and common mode chock. The circular space on the small board
is the position of the differential mode filter inductor on the smallboard.
The back of the small board is printed “Designed by Cuktech.”
Two rectifier bridges on the other small board, used to spread heat.
The big and small electrolytic capacitors of high-voltage filter from Aishi.
The 100μF capacitor is used for rectification and filtering,
18μF capacitor is used to reduce current ripple. Mater control chip of switching power
supply adopts ON Semiconductor NCP1342. This is a high-frequency QR quasi-resonant
flyback primary PWM controller, driving Navitas GaN Power Chip.
Turn on at the bottom of the electrical resonance to achieve quasi-resonant flyback,
and reduce switching losses. And this controller also
supports overheating protection. There is a thermistor under it,
can detect the temperature rise of the charger. And then, sent it to the master control chip.
Turn off the signal output when overheating, avoiding high-temperature damage.
The primary switch tube adopts Navitas NV6115 GaN power chip, whose withstand voltage is 650V.
Navitas integrates the driver, GaN switch tube and circuit into one chip.
This charger uses a planar transformer. Heat sinks wrapped with tape are pasted on both
ends of the small board to help dissipate heat. There are two solid output capacitors
in the middle of the two USB receptacle ports, fixed by glue.
An aluminum heat sink wrapped by insulating tape is next to the USB-C port.
Xiaomi adopts this method to replace the thermal pad.
The cost is higher, but the effect is better. Remove the small plate of the planar transformer.
You can see the synchronous rectifier controller and the rectifier tube.
There is also a VBUS switch tube. A layer of insulating tape is stuck
on the other side of the planar transformer.
There is a protocol chip at the output. We can see the synchronous rectification
circuit and the protocol chip are all on the circuit board of the planar transformer.
This design can shorten the cable length, reduce interference and improve space utilization.
Xiaomi 65W GaN charger reduces the size of the transformer by improving switching frequency.
And use the circuit board of the planar transformer to weld the synchronous
rectifier and Type-C output circuit. And there is a blue thermal pad between the
magnetic core and the transformer circuit board. It can conduct the coil’s heat to the core to
enhance heat dissipation and increase the power density of the transformer.
Break it down.
It seems like coil design.
The secondary synchronous rectifier controller adopts MPS MP6908A,
which supports the 600KHz switching frequency. This is Toshiba’s synchronous rectifier,
TPH4R50ANH. USB PD fast charge protocol chip
adopts powerful Cypress CYPD3174, which supports PD3.0, PPS and has a built-in ARM microprocessor.
The output VBUS switch tube adopts Toshiba TPCC8104.
USB-C receptacle port is spot welded in the hollow of PCB.
Let’s take a look at the small board of USB-A port.
USB-A port is pasted with high-temperature tape. There is an output VBUS switch tube next to it.
A customized chip and a step-down inductor are on the back.
Clean up the motherboard and remove all components.
A small black rubber pad in the middle of the front supports electrolytic
capacitors for high-voltage filter. Two Y capacitors are connected in series.
USB-A port output is filtered by Kemet tantalum capacitors, which is very expensive.
SMD package can reduce height and space occupation.
Synchronous buck-boost converter of USB-A port adopts Southchip SC8721.
It integrates four switch tubes for buck-boost voltage conversion.
Converted the 5 to 20V of USB-C port into 5 to 12V voltage.
Cypress CYPD3174 also controls the protocol of the USB-A port.
Communicate with SC8721 through the I2C interface to adjust output voltage.
Ok, that’s all for today’s teardown. Xiaomi’s GaN charger continues the high power density design
and adopts multiple small plates to increase space utilization.
If you have some old devices that need to be charged and don’t want to
sacrifice the size and power, this charger will be a good choice.
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