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Difficulty: MediumMobile Device Ports and Accessories

A mobile user connects an external display to a mobile device's USB Type-C port using a standard USB Type-C charging cable, but no video signal is detected on the monitor. The user verifies that the external monitor and the monitor's input settings are working properly. Which of the following is the most likely cause of this issue?

  1. The USB Type-C cable being used lacks support for DisplayPort Alternate Mode and only carries power and USB 2.0 data.Answer
  2. B
    The mobile device requires a cable with an active Thunderbolt 4 controller embedded in order to transmit video signals over USB Type-C.
  3. C
    The Mobile Application Management (MAM) policy on the device has disabled physical video output capabilities.
  4. D
    The mobile device is using POP3 for background data synchronization, which restricts video bandwidth across external ports.

Answer

The USB Type-C cable being used lacks support for DisplayPort Alternate Mode and only carries power and USB 2.0 data.
While USB Type-C provides a universal physical connector, not all USB Type-C cables contain the physical wiring necessary to support DisplayPort Alternate Mode (DP Alt Mode). Many bundled charging cables are wired only for USB 2.0 data lines and power delivery, rendering them incapable of carrying video signals to an external monitor.

Step-by-Step Solution

1
Identify the physical connection type and symptoms.
The user is attempting to output video from a mobile device's USB Type-C port using a basic USB Type-C charging cable, but no video signal is received.
USB Type-C is a physical connector form factor that supports multiple underlying protocols and pin configurations depending on the cable specifications.
2
Analyze cable capabilities and protocol requirements.
Video output over USB Type-C relies on DisplayPort Alternate Mode (DP Alt Mode), which requires high-speed data lanes in the cable.
Many standard charging cables only include wiring for power delivery and legacy USB 2.0 signals to reduce manufacturing costs.
3
Select the correct root cause.
Replacing the charging cable with a USB-C cable rated for video transmission (DP Alt Mode) will resolve the issue.
The issue stems from cable wiring limitations rather than software policies or protocol confusion.

Key Concept

USB Type-C Connector versus Alternate Mode Protocol Capabilities
Estimated Time:1m 0s
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Topics

Mobile Device Ports and Accessories

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