Testing Methodology and Documentation

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Testing USB Cables

USB Cables can be used to charge, transfer data between devices, connect periphericals to your computer or phone or connect computer or phone together. Consequences of using non tested cables to charge your devices are illustrated on Total Phase blog.

We are testing 5 different categories of characteristics for each cable:

  • Appearance
    • Total cable length (cm)
    • Cable length w/o plugs (cm)
    • Cable diameter (mm)
    • Cable color
    • Plugs color
  • Charging
  • Data Transfer
  • Safety & Security
    • Continuity
    • Quiescent current
    • Plug 1 implant presence
    • Plug 2 implant presence
    • Low DC Resistance
  • Compatibility
    • Plug 1 type
    • Plug 2 type
    • Plug 1 width (mm)
    • Plug 2 width (mm)
    • Plug 1 thickness (mm)
    • Plug 2 thickness (mm)
    • E-Marker VDOs

Based on the results of the tests in each category, the product is either recommended for a specific usage such

Test equipement and basic test protocol

  1. Lenovo Thinkpad X1 carbon Gen7 to record all test results.
  2. Test with Total Phase Advanced cable tester v2 according to documentation.
  3. Measure cable external characteristics with caliper and tape measure.
  4. Test for max supported voltage, current and power with Passmark USB Power delivery tester.


USB cables can be recommended for 3 different usages:

  • Device charging:
  • Laptop charging:
  • Data transfer:

Detailed test protocols

Testing USB Type C Cables

  1. USB 2.0 Type C cables
  2. USB 3.1 Gen 2 Type C cables

Recurrent problems found on USB cables

  • DC resistance too high: We often notice higher DC resistances than the allowed values for USB spec depending on how your insert the cable or how the cable is bent etc on mostly Ground cables and Pins. We allow up up to 2 times higher than the max value on some pins. A DC resistance 2 times higher is still a safe value.
  • VBUS through cable set to false: values in E-marker VODs: In reality those values are not check except the max supported current and voltage for PD2 and PD3. This could prevent devices from charging.
  • USB SuperSpeed Signaling set to USB 3.1 Gen 2 (0b010): E-marker is programmed like for a High Speed USB cable but the wiring of the cable corresponds to USB 2.0.
  • Signal integrity is too low: Signal integrity is too low meaning the data transfers won’t work propery.
  • Quiescent current too high in steady state in the E-marker: The e-marker in steady state is using too much electricity. It can impact power efficiency and dissipates heat from each USB plug.