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tl;dr: read title. Thunderbolt 3 hubs often have a "power delivery" port (alt: usb-c port that may support usb-pd). Are they input only, or also output, or 'maybe, good luck getting the specs'? Is there some way to get 70 watts power output from a hub connected to a TB3 port?

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I have a project I'm designing, and one of my needs is a thunderbolt 3 hub that (among others things) allows me to pull power from it (I think about 72 watts?). It was only after looking at several ads that I realized they all show power going into those power delivery ports, not out of them.

I'm a bit at a loss. I know that supporting PD is an optional part of the USB-C spec, iirc, so I can't trust USB-C ports on TB3 hubs to necessarily support USB-PD either, right?

For my project, I need a hub that

  1. Has two video outputs (preferably two HDMI ports, but just need two independent video outputs)
  2. Can supply about 70 watts of power output (so, probably via PD) that it pulls from the thunderbolt port.

Is this feasible/reasonable/possible?

(Btw, I really don't need it to be in the form of a finished 'hub' product--if it's possible to get a raw chip that has those ports on them, that would be even better, I just don't know how to look for such things.)

Kyle Baker
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3 Answers3

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You might face difficulties finding a hub that can fulfill your requirements due to the power limitations of USB-C/TB3/TB4 ports on laptops.

TB3 ports typically have a power output limit of 15W. Consequently, hubs connected to these ports cannot supply more than 15W to peripherals unless they have an external power source too.

The power output by a USB-C port on a device is referred to as "bus power". Here's a brief summary of the power output for different port types:

  • USB-A (2.0, 3.0) ports usually output 5W (5V at 1A).
  • USB-C ports typically output either 7.5W (5V at 1.5A) or 15W (5V at 3A).
  • Thunderbolt 3 ports generally output 15W (5V at 3A).
  • USB-C ports implementing USB-PD 3.0 can receive up to 100W (20V at 5A).
  • USB-C ports implementing USB-PD 3.1 can receive up to 240W (48V at 5A).

Unfortunately, marketing materials seldom mention the output power. You should consult your device's specifications (provided by the manufacturer) to find the output power limit for each port. Depending on the USB controller configuration, the limits mentioned above might be shared across multiple ports.

If you want to power displays, there are several excellent portable USB-C monitors available. The "LG Gram +View (16")" uses a single USB-C cable for power and video signal. According to LG, it requires 7.5W of power and should be compatible with any TB3 port, or USB-C port supporting "DisplayPort Alt Mode".

The reason higher output USB-C/TB3/TB4 ports are not common in laptops is due to space and heat constraints. For example, Apple's power adapters increase in size with higher output capacity. Gallium Nitride (GaN) adapters offer greater space efficiency, but the demand for integrating them into devices like laptops is currently low.

joewoodio
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Thunderbolt 3 hubs only have the ability to input power to supported devices; it is not reversible. They cannot output power.

Virtuality
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HUB or DOCKING STATION ?

A HUB will draw power from your PC in order to power the peripherals. I doubt any laptop would have 72W of extra power budget to deliver to a hub, but it might be doable with a tower PC. Some hubs though have a pass-through charging UBS-C connector on which to connect your power brick, so you need to connect only one cable to your laptop: in that case it will provide power. Here's a [random example hub with pass through charging] [1]

A Docking Station has its own power brick and is designed to output Power to your laptop or whatever is there to draw power. The TB /USB-C spec limits are 100W, so you should be able to find something suitable. Here is [a random example with 87WPD][2]

Getting the chips probably will cost you much more than dissecting an existing hub / docking station, unless you have to buy hundreds of them

[1] : https://www.amazon.com/dp/B07ZVKTP53/ref=cm_sw_r_cp_awdb_imm_t1_1HGJPY4NVETSXC02VF7P

[2] : https://www.amazon.com/dp/B07CZPV8DF/ref=cm_sw_r_cp_awdb_imm_t1_Q0EAP2B6XT5W6QV91KZV

1NN
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