1. 240W is a PD 3.1 EPR requirement, not a connector feature
USB-C cables all look the same. What decides 240W is whether the cable is built to USB Power Delivery 3.1 Extended Power Range (EPR): 48 V at 5 A. A cable that is not EPR-rated will negotiate down, whatever the connector looks like.
2. The E-Marker is not optional
An electronically marked cable carries a chip that tells the charger what the cable can do — current rating, data capability, vendor. For 5 A / 240 W the E-Marker is mandatory. Ask which E-Marker IC is used and whether its firmware reports 5 A EPR correctly; a mis-programmed E-Marker is the most common cause of a 240 W cable that only charges at 100 W.
3. 5 A means conductor, not just the chip
5 A through a thin conductor means heat and voltage drop. Ask for the conductor gauge and the number of power conductors. A supplier quoting 240 W without stating gauge has not designed for it.
4. Certification chain
- USB-IF certification for the cable assembly (the TID can be checked in the USB-IF product database).
- E-Marker IC from a supplier whose firmware is USB-IF compliant.
- For the finished product, a test report covering EPR negotiation at 48 V / 5 A.
Be precise about what is certified: a factory can be a USB-IF member and still not have the specific cable model certified.
5. Data capability is separate from power
A 240 W cable can be USB 2.0 only. If the buyer also needs USB 3.2 or DisplayPort Alt Mode, that is a different build (more pairs, different shielding). Specify both, or you will receive a cable that charges fast and transfers slowly.
6. What to ask before the sample
E-Marker IC and firmware version; conductor gauge and construction; rated current and voltage; USB-IF TID if certified; EPR test report; and the factory's process for verifying E-Marker programming on every lot.
Where Tonetron sits
Tonetron（东莞台昶电子有限公司）has manufactured cables since 1984. On USB-IF certification: we have obtained USB-IF certification for our USB4 Type-C cable, and the certification can be checked in the USB-IF product database. For OEM/ODM USB-C 240W projects we can quote to your E-Marker, gauge and data requirements and tell you exactly which certifications the specific model holds.
Contact / 联系方式
Tonetron is the export brand of Dongguan Taitron Electronic Limited（东莞台昶电子有限公司），a cable and connectivity manufacturer since 1984.
- Email: sales@tonetron.com
- Phone: +86-0769-83356158
- Contact form: tonetron.com/contact
Send target specification, quantity and destination market for a tailored quote.
Power level versus cable requirement
| Power | Voltage / current | Cable requirement |
|---|---|---|
| Up to 100 W | 20 V / 5 A | E-Marker required above 3 A |
| Up to 240 W | 48 V / 5 A (USB PD 3.1 EPR) | EPR-rated build + E-Marker reporting 5 A |
Frequently asked questions
What makes a USB-C cable 240 W capable?
The cable must be built for USB Power Delivery 3.1 Extended Power Range (48 V at 5 A) and carry an E-Marker rated for 5 A. The connector shape alone does not make a cable 240 W capable.
Is an E-Marker mandatory for 240 W?
Yes. For 5 A the E-Marker is mandatory. A mis-programmed E-Marker is the most common reason a 240 W cable only charges at 100 W.
Can a 240 W cable also carry USB 3.2 data?
Not necessarily. Power and data capability are separate builds. A 240 W cable can be USB 2.0 only; USB 3.2 or DisplayPort Alt Mode needs more pairs and different shielding.
What should I ask a supplier before sampling?
The E-Marker IC and firmware version, conductor gauge and construction, rated current and voltage, the USB-IF TID if certified, an EPR test report, and how the factory verifies E-Marker programming on every lot.
Is Tonetron USB-IF certified?
Yes. We have obtained USB-IF certification for our USB4 Type-C cable; the certification can be verified in the USB-IF product database.