An E-marker is a tiny embedded chip inside a USB-C cable that communicates the cable's charging capabilities to connected devices. It allows host systems and power supplies to negotiate high charging rates safely and adapt to fluctuating power demands.
Why E-Markers Matter for Power Delivery
USB Power Delivery relies on E-markers to negotiate power delivery levels above standard limits between a charger and a connected device. By signaling the maximum current and voltage the cable can safely carry, the chip ensures proper charging rates and protects connected hardware.
E-marker Requirements
E-markers are required for cables that carry over 3 amps, this includes most USB Type-C cables included with our docking stations. Thunderbolt certification also requires an E-marker and all of our Thunderbolt 3, Thunderbolt 4, and Thunderbolt 5 data cables include an E-marker.
How does the E-marker identified to the user?
For the most part the existence of the E-marker in the cable will be unremarkable, they simply do their job in combination with the USB or Thunderbolt host controller and downstream device, or power supply. Either Windows or macOS may show a notification if an unmarked cable is used with a device that normally requires an E-marker, this can also limit the capability of said devices. We normally recommend using the original USB Type-C or Thunderbolt cable that was included with the device for connecting to the host computer.
Applicable To
- USB-C charging cables
- Thunderbolt cables
- USB Power Delivery (PD) enabled devices
- High wattage USB-C power supplies
If you have any questions please feel free to contact us at support@plugable.com and we'll be happy to help!
