Pass-Transistor Power Management for Minute Short Isolation
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Solution Overview
Problem
Conventional power management circuits fail to deactivate the power supply voltage in display devices when a minute short defect occurs, leading to potential damage or malfunction.
Innovation Solution
A power management circuit that includes a boost converter, a pass transistor, and an overcurrent detect circuit, which senses current flowing through the pass transistor to generate an overcurrent detect signal and deactivate the second power supply voltage if an overcurrent is detected, while also adjusting voltage levels using feedback circuits to compensate for on-resistance drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power management circuits are used, then the circuit structure is simple, but the circuit cannot detect minute short defects and fails to deactivate the power supply voltage
Solution Approach 1:
The patent introduces an overcurrent detect circuit as an intermediary component between the pass transistor and the power supply voltage control system. This circuit includes a sensing transistor that mirrors the current through the pass transistor, an operational amplifier that compares the sensing current with a reference current, and generates an overcurrent detect signal when a short defect is detected. This intermediary detection mechanism enables minute short defects to be identified without requiring complete redesign of the entire power management system.
Solution Approach 2:
The patent implements a feedback mechanism where the overcurrent detect circuit continuously monitors the current flowing through the pass transistor and provides feedback signals to control the activation of the second power supply voltage. When the sensed current exceeds the reference current threshold, the feedback signal triggers deactivation of the affected power supply while maintaining others, enabling dynamic defect response without system-wide shutdown.
2Object-affected harmful factors
If the power management circuit deactivates all power supply voltages upon detecting a short defect, then safety is improved, but the first power supply voltage needed for high gate voltage and gamma voltage generation is also deactivated
Solution Approach 1:
The patent segments the power supply system into multiple independent power supply voltages (first power supply voltage for high gate voltage and gamma voltage, second power supply voltage for output buffer, third power supply voltage for scan driver). When a short defect is detected in one branch, only the affected power supply is deactivated while others remain active. This segmentation allows localized defect response without compromising the entire display system's operation.
Solution Approach 2:
The patent applies local quality by implementing defect-specific deactivation strategies where different power supply voltages are deactivated based on the location and nature of the detected short defect. The overcurrent detect circuit identifies which specific power supply branch is affected and triggers selective deactivation, ensuring that only the minimal necessary power supply is turned off to prevent damage while maintaining display functionality through other active power supplies.
Data Source
AI summary
A power management circuit is disclosed that includes a boost converter, a pass transistor, and an overcurrent detect circuit. The boost converter is configured to convert an input voltage into a first power supply voltage. The pass transistor is configured to transfer the first power supply voltage as a second power supply voltage after a predetermined time from a time point at which the first power supply voltage is activated. The overcurrent detect circuit is configured to perform an overcurrent detect operation by sensing a current flowing through the pass transistor. A display device is also disclosed that includes the power management circuit.