USB-C PD Hub: Understanding Power Negotiation
Power Delivery is a negotiation, not a wire. If any element in the chain cannot take part, the link falls back to something slower and the laptop charges accordingly.
Quick Answer
A USB-C PD hub accepts a Power Delivery charger, uses a little power for itself and passes the rest to the laptop. Wattage tiers are 15, 27, 45, 60, 100 and, with newer standards, up to 240 W. Cables above 60 W must be e-marked. A hub that does not support PD will pass no more than standard 5 V charging.
Wattage Tiers
| Tier | Typical use | Cable requirement |
|---|---|---|
| 15 W, 5 V 3 A | Phones and small tablets | Basic USB-C cable |
| 27 W, 9 V 3 A | Tablets and small laptops | Basic USB-C cable |
| 45 W, 15 V 3 A | Ultrabooks | Basic USB-C cable |
| 60 W, 20 V 3 A | Larger laptops | Basic USB-C cable |
| 100 W, 20 V 5 A | Workstation laptops | E-marked cable required |
| 140 W and above | High power laptops | E-marked cable and compatible hub |
What Breaks Negotiation
A non PD charger
An older 5 V charger supplies only basic charging regardless of the hub.
A basic cable
Without an e-marker chip the link caps at 60 W. This is the most common cause of slow charging through an otherwise capable hub.
A hub ceiling
Many hubs accept a maximum of 100 W, so a higher rated charger gains nothing.
A USB-A adapter in the chain
Power Delivery needs USB-C at both ends. Introducing USB-A ends the negotiation.
What PD Does Not Do
- It does not increase what a hub can supply to its own ports.
- It does not charge a device that does not support PD above its own limit.
- It does not replace the need for a supply on a self powered hub.
- It does not guarantee the laptop keeps up under heavy load.
Checking Your Setup
- Find the wattage the laptop expects.
- Check the charger rating and whether it supports Power Delivery.
- Confirm the cable is e-marked if above 60 W.
- Check the hub maximum input.
- Watch the charge rate under load to confirm the arrangement is sufficient.
Real-World Applications
- Single cable docking for a business laptop.
- Charging a tablet while using a display and a drive.
- A monitor arm with the charger hidden behind it.
- Travel with one charger for laptop and phone.
Related Guides
For hub power budgets, read USB-C power hub. For charger sizing in detail, see USB-C hub with power delivery. For self powered hubs, start with USB-C powered hub.
FAQ
Do I need a special cable for 100 W?
Yes. Cables above 60 W must be e-marked, otherwise the link is limited.
Will any USB-C charger work with a PD hub?
Any charger that supports Power Delivery. Plain 5 V chargers will not negotiate higher wattage.
Why does the laptop drain while plugged in?
Its consumption exceeds the passthrough wattage. Use a higher rated charger within the hub limit.
Does the hub need its own supply as well?
Only if its USB ports must power drives. Passthrough charges the laptop, not the hub ports.