Power Adapter Touch Detection for Smooth AC-DC Switching
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Solution Overview
Problem
Electronic devices face issues with sudden shutdown or malfunction when switching from AC power to DC power due to delayed CPU throttling, leading to inadequate power handling and potential battery damage, as they cannot immediately reduce operating frequencies when the power adaptor is disconnected.
Innovation Solution
Incorporating a proximity sensor in the power adaptor to detect user touch, initiating CPU throttling before detachment, and monitoring output wattage to switch to DC power mode safely, thereby reducing latency and preventing system failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CPU throttling is initiated after power adaptor disconnection, then the system can switch from AC to DC power source, but the electronic device may exhibit abnormal behavior such as display screen blackout or sudden shutdown due to delayed power supply switching
Solution Approach 1:
The system initiates CPU throttling in advance upon detecting user touch on the power adaptor, before the actual power source switching occurs. This preliminary action ensures that the CPU is already throttled when the power adaptor is disconnected, preventing system instability, display blackout, or sudden shutdown that would occur with delayed throttling initiation.
2Productivity
If the electronic device operates at high operating frequencies when switching to DC power mode, then it can maintain processing performance, but the battery may be damaged or the device may malfunction due to inadequate power supply
Solution Approach 1:
The system performs CPU throttling before the power source switches from AC to DC, ensuring that the CPU operating frequency is reduced in advance. This prevents the battery from being overloaded and avoids device malfunction, while still allowing the device to operate at optimized frequencies once the power transition is complete.
3Use of energy by moving object
If conventional throttling mechanisms are used, then power consumption can be reduced after power adaptor disconnection, but the time required to initiate throttling depends on system design and configuration, leading to potential system failures
Solution Approach 1:
The system uses user touch detection on the power adaptor as a trigger signal to initiate CPU throttling before power adaptor disconnection. This provides a consistent and reliable timing mechanism that is independent of system design variations, ensuring that throttling always starts at the optimal moment regardless of system configuration.
Solution Approach 2:
The system monitors the power supply status and user interaction with the power adaptor, using this feedback to determine the optimal timing for CPU throttling initiation. By detecting user touch on the adaptor, the system receives real-time feedback about upcoming power source changes and adjusts throttling timing accordingly, preventing system failures.
Data Source
AI summary
An example electronic device includes a controller to determine a user touch detection by a power adaptor coupled to the electronic device to operate the electronic device in an AC power mode. The power adaptor may comprise a proximity sensor to detect a user touch for detachment of the power adaptor from the electronic device, and a control circuit to operate a configuration pin in a low output mode to signal user touch detection. The controller may initiate central processing unit (CPU) throttling to reduce power consumption by the electronic device. The controller may further stop CPU throttling in response to detecting that the power adaptor has been detached from the electronic device. Further, the controller may switch the electronic device to a DC power mode to operate using DC power supplied by a battery of the electronic device in response to power adaptor detachment.