![]() ![]() If you connect such a dock to your laptop without plugging a charger into it, the laptop will feed this dock with 5 V, capped at either 1.5 A or 3 A, depending on the laptop. Imagine a USB-C dock with a USB3 port, a HDMI port, and a USB-C charger input port. If you don’t yet appreciate the complexity, let me walk you through a complex scenario that is made easy by USB-C. Docks For Everyone, Let Nobody Leave Dissatisfied USB PD capabilities are way beyond “give me this voltage limited by this current”, too – devices can query each other’s power role preferences, charging states, swap power roles on the fly, determine what a cable is capable of, and do all of that with safety in mind. It’s thoughtfully designed – the communications are forwards- and backwards-compatible, with new 140 W EPR chargers happily charging old 60 W devices at 60 W rates, and 60 W chargers still usable for slower charging of 140 W-craving devices. There’s a mindboggling amount of communication possible through USB-C, letting us build devices smarter than ever before. Most importantly, USB-C PD is immensely powerful. It’s a constant-baudrate bidirectional protocol, there’s CRC checks, response timing requirements, and it’s used for basically everything USB-C – even high-speed protocol negotiations. You can’t get beyond 5 V with just resistors though – you’ll need digital communications over the CC line, using a protocol called USB PD (Power Delivery) – which lets a device and a PSU negotiate power requirements in a featureful way. You can also get voltages in-between, down to 3.3 V, even, using a PD standard called PPS (or the AVS standard for EPR-range chargers) – it’s not a requirement, but you’ll find that quite a few USB-C PSUs will oblige, and PPS support is usually written on the label. These steps are referred to as SPR, and EPR adds 28 V, 36 V and 48 V steps into the mix – for up to 240 W necessitating new cables, but being fully backwards and forwards compatible, and fully safe to use due to cable and device checks that USB-C lets you perform.Ī charger has to support all steps below its highest step, which means that 20 V-capable chargers also have to support 5 V, 9 V, and 15 V as well – in practice, most of them indeed do, and only some might skip a step or two. The usual voltage steps of USB-C are 5 V, 9 V, 15 V and 20 V 12V support is optional and is more of a convention. USB-C power supplies always support 5 V and some are limited to that, but support for higher voltages is where it’s at. If 15 W isn’t enough for your device, let’s see how we can get you beyond. This applies to power too after all, not all devices will subsist on 15 W – some will want more. You get way more bang for your buck with USB-C. ![]() Today, all you need is a USB-C socket with two resistors – or a somewhat special chip in case the resistors don’t quite get you where you want to be. As a hobbyist, you no longer need to push 3 A through tiny MicroUSB connectors and underspecced cables to power a current-hungry Pi 4. It fights proprietary phone charger standards by explicitly making them non-compliant, bullying companies into making their devices work with widely available chargers. ![]() USB-C eliminates proprietary barrel plug chargers that we’ve been using for laptops and myriads of other devices. ![]()
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