Ethernet power line adapters have become increasingly popular in environments where Wi-Fi can be intermittent or non-existent. While powerline systems have become more mainstream in the past few years, their invention dates back to 1922 when electrical wiring was becoming more popular in houses and streets. The first use of sending signals over power lines was for telemetry purposes with carrier frequencies between 15kHz and 500kHz.
In this teardown, we will see what makes up a standard powerline adapter.
The unit has three LEDs on the front to indicate power, an Ethernet connection, and a network connection.
LED indicators and the "pair" button
Adapters from different manufacturers are usually compatible but this unit is not compatible with older models (100mbps). This is why such units come in pairs so that one is connected to the main router and the other is connected to the device that requires network access (such as a PC).
This powerline adapter also has a "pair" button, which allows it to be paired with a specific adapter for communication between two points (such as two PCs).
Ethernet connector on the adapter
Serial number on the adapter
Getting Access Inside
Like many mains-powered devices, this unit has no screws and is molded as to prevent access to the internal high voltages. Therefore, an invasive method is needed to get inside to see how this thing ticks.
In my case, a small drill was used to create a hole whereby a lever was inserted to remove the front cover.
Back of the main PCB
One IC that can be seen in the top half of the main PCB is the LNK623DG. This IC is for power regulation and constant voltage control, which would make sense considering that this device needs to use AC power as a power source. See the datasheet here.
Close up of the top half of the main PCB
The bottom half of the main PCB shows a serial flash chip 25Q80 with a capacity of 8 Mbits. Devices like these are used to hold device information such as a MAC address and network configurations. See the datasheet here.
Close up of the bottom half of the main PCB
With the main PCB, drawn away from the housing, the mains connection becomes visible.
Interestingly, the mains connection is done via uninsulated metal strips which explains the lack of screws. If wires with insulation were used, then security screws would be a suitable construction method. Since this unit uses bare metal conductors, it is better practice to use no screws at all and make it near impossible to gain access inside.
You may also notice a reflective gold piece—this is actually covered in a clear plastic layer. This may be installed for EMC reasons to prevent interference between the mains and the controller board.
The mains connection, main PCB, and shielding
Mains connection close up
The main PCB shows regulation and filtering components including transformers, inductors, and large capacitors. Interestingly, many of the parts are through-hole which makes manufacturing more difficult (a PCB like this may need manual soldering).
The main PCB
Top of the main PCB
The main controller is an Atheros AR7420-AL3C, which is specifically for LAN networks. The IC includes an ARM CPU, internal ethernet switching, ADC, DAC, SPI, and GPOs. The ethernet controller can handle up to500Mbps PHY rates over powerline connections and has inbuilt hardware encryption (AES 128-bit).
The Atheros processor
The second IC on this PCB is the Atheros AR1540, which is partnered with the main controller. This is an ethernet line driver supporting between 2MHz and 68MHz operating frequencies, integrated Tx line driver, and a programmable Tx gain control amplifier.
The sister IC to the main controller
The last main IC on the top layer of the PCB is the AP35502 which is a DC-DC buck converter that can handle up to a load current of 2A with efficiency up to 95%.
The DC-DC converter IC
The powerline adapter demonstrates the importance of miniaturization of components when trying to get an entire ethernet network adapter to fit in a small space. The plug of this device is so small that it doesn't prevent other plugs from fitting into adjacent sockets.
The main controller, the Atheros AR7420-AL3C, is a classic example of how microcontrollers are becoming increasingly complex and integrated with inbuilt stacks, encryption, and peripherals with plenty of GPIOs to spare.
Thanks for reading! Stop in next week for another Teardown Tuesday!
Next Teardown: Pulse Oximeter