Having devoted one of last month's posts to a tutorial on USB's signaling, connector, and power delivery evolutions toward latest-generation USB-C (USB Type-C, to be precise), I thought it'd be an appropriate follow-up to devote one of this month's posts to an analysis of the available USB-C expansion options, specifically for my recently acquired Google Pixelbook (along with, I'm presuming, future systems I purchase, which will also likely be USB-C-centric), as well as an exposé on which candidates earned my hard-earned cash.

Cables and chargers

The Pixelbook comes with a 45W power adapter and USB-PD-capable USB-C-to-USB-C cable. That combo will suffice for desktop-use purposes, but I always like to have a spare power adapter on hand to toss in my travel bag. Extras from Google will set you back $60 USD each, but given USB-C's increasing ubiquity, I suspected I could find less expensive options elsewhere. I was right, although it took a bit of work to get to a successful endpoint.

My initial acquisition was a refurbished 45W HP-branded adapter sold by Woot for $31.99 plus tax, with free shipping courtesy of my Amazon Prime membership (Woot is now part of Amazon). The USB-C cable on this particular unit is non-detachable, however; it's permanently connected to the AC/DC module (the only thing detachable with this particular product is its AC power cord). So I next went in search of a standalone USB-PD cable for use with the Anker PowerPort+ 5 60W charger I'd recently picked up on sale for $24.74 at Amazon.

Only one problem ... whereas an Amazon-branded 3' USB Type-C to USB Type-C 2.0 (480 Mbps) cable only costs $6.99 as I write this, its USB Type-C to USB Type-C 3.1 Gen1 (5 Gbps) cable sibling is $18.99, and both are only spec'd to support 5V @ 3A (15W) max power delivery capabilities. Google's own standalone cable costs $20 for the same 3' span (along with, presumably, the same power limitations ... I can't find any spec mention on the company's website, but the cable's shown alongside a smartphone, not a beefier-battery-equipped system). And although USB-C has matured since its early horror-story days, I'm still loath to try out lesser-known brand cables that might fry my hardware.

What I ended up doing instead was coming across (and acquiring) an Inateck 60W USB-C wall charger with included (and detachable this time) 6' cable on sale for $22.19 at Amazon. Here's a more recent $11.52-on-sale 61W (??) charger-plus-cable combo from Runpower, which looks like an Apple clone.

Hubs

The Pixelbook, as I've written before, has limited built-in system interface capabilities: a USB-C connector on either side, along with an analog audio jack on the left edge. One of the USB-C connectors will frequently be tethered to an AC power adapter for system power and battery recharging purposes. This means that the other USB-C connector will frequently be tethered to a multi-interface hub for system expansion purposes.


Belkin's USB-C 3.1 Express Dock HD

When the Pixelbook is in use at my desk, a high-end hub with a diversity of interface options, and complete with DC power generation capabilities to boot, is useful. Most products like this, whether for USB-C or Thunderbolt 3, typically cost several hundred dollars. However, I happily came across Belkin's USB-C 3.1 Express Dock HD, complete with a 3' USB-C cable, on sale for $79.20 at Amazon. In addition to supplying up to 60W of power to a USB-C 3.1-connected system, the Express Dock HD also transforms that same USB-C 3.1 connection into a variety of other external interface options:

  • Replicated USB-C 3.1
  • 5 Gbps USB Type-A 3.0 (three available)
  • 4K @ 30Hz HDMI
  • Gigabit Ethernet, and
  • Analog audio (one I/O, one output)

Amazon's product page makes no mention of Chrome OS support, only MacOS and Windows, nor does the product overview page on Belkin's own website. But buried in the product FAQ is the reassuring Chrome OS mention I was looking for.

What about a hub for on-the-road purposes? Here the interfaces-offered list can often be more modest; GbE is probably more of a nice-to-have versus a necessity when traveling, for example. And since the road warrior will probably already be toting the system's wall wart power supply, built-in DC generation is also a non-essential (conversely, the ability to self-power the hub via its USB-C system connection versus requiring a wall wart of its own is highly desirable). But size and weight are more important here than when at the office desk.

Initially, I thought about going with a side-mounted hub such as this unit from Suneon, on sale for $19.60 as I was writing this and including two USB 3.0 ports, an SD/Micro SD card slot, and a USB-C charging port. I ended up not going this route, however, for three primary reasons:

  1. It was fairly difficult to find a hub of this type that didn't include two USB-C system interface connectors, thereby being intended for use with Apple's latest few years' worth of MacBook Pros.
  2. All of the side-mounted hub candidates I could find were intended for use on the system's left side, which would have blocked my access to the Pixelbook's analog audio jack. I could have mounted the hub on the right side instead, but that would have been awkward for multiple reasons; either the hub would have extended backwards out the system's backside, or (since USB-C is reversible) all of its expansion connectors would have been upside-down.
  3. The whole concept of physically tethering a still-fairly-substantial size-and-weight piece of hardware to an expensive system via only a single flimsy connector gave me the long-term-reliability heebie-jeebies.

Instead, I selected another discrete hub, this time from HooToo, on sale at the time for $28.89. In addition to passing through the USB-PD power and charging functions from a connected power supply to the system (and itself being powered by that same system connection), it also converts the USB-C port into three 5 Gbps USB 3.0 Type-A connections, a 4K HDMI interface, and a SD card reader/writer. And since it mentions "Google Chromebook" right in the Amazon product page title, there's no doubt as to its Chrome OS cognizance.

[Continue reading on EDN US: Dongles]

Brian Dipert is Editor-in-Chief of the Embedded Vision Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company's online newsletter.

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