Charger Self-Test Mode for Leakage Current Detection
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Solution Overview
Problem
Leakage currents at charger connectors, caused by foreign objects or liquids, pose a safety risk due to inadequate protection by existing protection circuits, especially when the charger connector is damaged or not properly connected.
Innovation Solution
A charger system with a self-test mode that detects voltage or current anomalies at the connector pins, adjusting the supply voltage based on the detection results to prevent overheating, and includes a transistor and resistor configuration to manage ground pins and detect foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection circuit within a charger IC is used to detect leakage current, then some protection is provided, but the protection is inadequate because the leakage current occurs at the charger connector and cannot be detected or avoided
Solution Approach 1:
The system performs a self-test mode before normal charging to detect potential leakage current paths. The charger controller applies a test voltage to the connector pins and measures the resulting current to identify foreign objects or damage before actual charging occurs, preventing harmful leakage currents from causing overheating or safety issues.
Solution Approach 2:
The charger IC's controller performs self-diagnosis by testing its own connector for abnormalities. The system uses internal resources (power pins, detection circuits) to automatically detect leakage current paths without requiring external testing equipment, enabling the system to identify and avoid unsafe charging conditions.
2Productivity
If the charger operates in normal mode to charge the battery, then charging function is provided, but leakage current may cause temperature increase and safety danger
Solution Approach 1:
Before entering normal charging mode, the system executes a self-test mode that applies a test voltage to the connector and detects any leakage current paths caused by foreign objects or damage. This preliminary detection prevents the system from proceeding to normal charging if unsafe conditions are detected, thereby avoiding temperature increase and safety hazards while preserving the charging function when conditions are safe.
3Reliability
If the charger IC protection circuit is designed to detect leakage current, then protection may be improved, but the leakage current is seldom generated when no plug connects making circuit design difficult
Solution Approach 1:
The system implements periodic self-testing during charging operation, switching between normal charging mode and self-test mode. The controller periodically interrupts charging to perform quick leakage current detection, maintaining protection capability without requiring continuously complex circuitry. This periodic approach simplifies the overall circuit design compared to continuous monitoring while still providing effective leakage current detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively detects and mitigates leakage currents, preventing overheating and ensuring user safety by adjusting the supply voltage or current, even when the connector is not connected to a power source.
Implementation Method 1
a detector to detect the current or voltage of at least one pin of the connector to generate a detecting result
Implementation Method 2
a leakage current generated when the electronic device is charged by a power adapter may cause a temperature of the charger connector to increase
Data Source
AI summary
An electronic device includes: a connector, arranged for coupling to a power supply external to the electronic device, wherein the power supply is arranged to provide a supply voltage to the electronic device to charge a battery of the electronic device; and a charger, coupled to the connector and selectively operated in a normal mode or a self-test mode, wherein when the charger operates in the normal mode, the charger is arranged for receiving the supply voltage via a power pin of the connector to charge the battery of the electronic device; and when the charger operates in the self-test mode, the charger provides a specific voltage to the power pin of the connector. The charger includes a detector to detect the current or voltage of at least one pin of the connector to generate a detecting result, and the supply voltage is set based on the detecting result.