Rant: The USB Type C Cable Chaos

USB Type C Breakout Board

Recently, I misplaced my OnePlus phone’s charging cable and resorted to a Type A to Type C USB3 cable with their original charger. Voila, OnePlus’s superfast charging didn’t kick in with the alternate cable, even though it was of better quality than their official one. This is not a new dilemma; I was curious about how they detect the cable change. Looking at the Type A end of the cable, it appeared similar to a regular USB2.0 Type A connector with the standard four lines: VBus, D+, D-, GND. Interestingly, there was an exposed middle GND-Drain line, which seemed odd. My hunch was that they might be employing some non-standard 1-wire communication over that line.

To delve deeper, I attempted to use a USB TypeC Breakout and probed each pin on the Type C end, but the GND-Drain pin wasn’t connected anywhere. This strongly hinted at the use of an eMarker chip in the cable head. These minuscule chips play a pivotal role in communication between devices and chargers, and that’s where the conundrum arises.

USB Type C cables were intended to establish uniformity and standards, but the industry has managed to turn it into a colossal mess. The market is flooded with seemingly identical Type C cables that differ drastically in performance. And that’s just the physical design part – add to it the proprietary charging protocols introduced by each company. From Apple to Samsung, Qualcomm to Xiaomi, and OnePlus/Oppo, every brand is pushing its unique charging approach, accompanied by flashy names like QuickCharge, Dash/Warp Charge, SuperCharge, and PD fast charging. Just to figure out the Voltage and Current needed.

What’s preventing companies from adhering to a universal standard? The lucrative $50+ billion cable and accessories market. If you purchase a device, you better buy its specific cables or risk a drop in performance due to vendor lock-ins. This issue becomes even more vexing today as companies often exclude chargers and cables when you buy a phone.

This mess won’t be sorted out anytime soon, with USB4 introducing more confusion. Wired cables will be weird in the years to come.

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Teardown: 7 Port Active USB3.2 Hub

Haven’t done a teardown in a while. Had a TP-Link UH700 7-port USB hub in my scrap pile(But it was working). It’s a 12V powered USB3 hub with 7 ports and Micro USB3 input. After a solid 15-minute struggle, I managed to pry it open – those clips were tough! Needed multiple spudgers for the job.

Coming to the internals, the star of the show is two RTS5411S USB3.2 Gen1 4-port Hub controllers(In the middle row) powering 7 ports with a 12MHz crystal. The 8th port is routed as an input to the second RTS5411S. Firmware configuration likely resides in 25Q40CT SPI serial NOR flash chips located on both sides of the PCB. A convenient soft latch button rests on the top left. The power section on the top right and middle contains a 12V input jack and step-down buck converter APW8720B to put 5V through to beefy N-channel MOSFETs CED3172 and a massive inductor at the output. This chip fuels downstream 5V supply and an adjustable 1117 LDO supports the 3.3V rail. Each of the 7 ports has a PTC fuse protection to avoid blowing up if one port draws more current. There is a single LED to show if a port is active and the good part is that LEDs are optically isolated with a cheapo(but effective) black foam. There seems to be space for 2 more USB2.0 charging ports on the right which I believe is for a different Hub model with the PCB. Use the same PCB and sell it as a 9-port device. More Profit.

What’s intriguing is that every port has a footprint for an ESD diode array, yet none of the 8 USB ports, including the input port, have been populated. This seems like a risky approach and a strict no-no in my books. My assumption is that TP-Link might have used these chips on the certification test board to pass tests but omitted them in production to cut BOM costs. Though against the rules, this is a practice I’ve seen before in consumer products from other companies too. These units are likely to struggle with ESD tests. Has anyone in low-humidity environments faced ESD problems with this model?

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