Jimu Zhilian
PRODUCT ENGINEERING · 6 MIN READ

How to define power, protocol and E-marker requirements for a USB-C cable

A practical sourcing checklist that prevents the most common sample revisions.

Start with the device and use case

"USB-C cable" is not a complete specification. Phone charging, laptop charging, high-speed data and industrial modules can require different conductors, shielding, PCB components and validation methods.

Define power before cable appearance

State the target voltage, current and power. A 60W cable and a 100W cable may need different conductor sizes, terminal structures and E-marker configurations. Cable length also changes voltage drop and thermal performance.

Confirm the data protocol separately

Charging power does not automatically define data capability. Specify USB 2.0, USB 3.x, USB4 or charging-only. High-speed protocols require controlled impedance, shielding and full assembly testing.

When is an E-marker needed?

An E-marker PCB communicates cable capability to connected devices. Its necessity depends on the power level, protocol and product architecture. The chip, PCB layout and firmware or identification requirements should be agreed before sampling.

RFQ checklist

  • Connected devices and application
  • Voltage, current and target power
  • Data protocol and video requirements
  • Cable length, jacket and flexibility
  • Target market, compliance and quantity