Question

Difficulty: HardLaptop Power Systems and Battery Management

A technician is configuring a newly deployed corporate ultrabook that features two physical USB Type-C ports. When connecting the manufacturer's 65W AC adapter to Port 1, the laptop charges properly and powers external peripherals. However, when connecting the exact same 65W AC adapter and cable to Port 2, the system displays a 'Plugged in, not charging' status in the operating system and fails to receive auxiliary power, despite Port 2 successfully transferring data to external drives. Which of the following best explains this behavior?

  1. Port 2 is a standard USB data port that lacks integrated USB Power Delivery (USB-PD) sink hardware capabilities.Answer
  2. B
    Port 2 is restricted because charging over USB Type-C requires a mandatory Thunderbolt active cable rather than a standard passive cable.
  3. C
    The laptop battery management system requires a manual deep-discharge calibration cycle to enable alternate charging ports.
  4. D
    Port 2 defaults to a lower wattage intake threshold, requiring the operating system power plan to be adjusted to high performance.

Answer

Port 2 is a standard USB data port that lacks integrated USB Power Delivery (USB-PD) sink hardware capabilities.
Although USB Type-C uses a uniform connector form factor, manufacturers frequently designate specific ports for Power Delivery (USB-PD) while restricting others to data transport. Without integrated USB-PD sink negotiation hardware on the secondary port, the power adapter cannot negotiate high-voltage power delivery to charge the battery.

Step-by-Step Solution

1
Analyze physical port behavior and functionality differences
Port 1 charges the laptop and transfers data, whereas Port 2 transfers data but refuses power input.
Physical USB Type-C connector shapes are standardized across devices, but individual motherboard ports can be wired for different feature sets (such as USB 3.2 data only vs. USB Power Delivery).
2
Evaluate hardware protocol negotiation requirements
Charging via USB Type-C requires dedicated USB Power Delivery (USB-PD) controller hardware on the port.
If a port lacks USB-PD sink circuitry, the connected power adapter cannot negotiate voltage and current profiles required to charge the laptop.

Key Concept

USB Type-C Feature Asymmetry and USB Power Delivery (USB-PD) Hardware Support
Estimated Time:1m 30s
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