Dynamic Over-Current Protection Circuit for Low-Impedance Short Detection
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Solution Overview
Problem
Existing over-current protection circuits in display devices face challenges in accurately detecting short circuits, particularly in low impedance situations, where the current may start small but increase over time, risking device damage due to incorrect threshold settings.
Innovation Solution
An over-current protection circuit with a detection circuit, a first protection branch, and a comparison circuit that detects current in real-time, delays the detection voltage, and compares it with a reference voltage to accurately determine when to cut off the current, using a delayer and field effect transistors to manage the switching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed threshold is used for over-current protection, then the circuit structure is simple, but the protection accuracy is poor and may miss short circuits or cause wrong determinations
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed threshold into a dynamic reference voltage that changes over time. The reference voltage is generated by delaying the detection voltage by a preset time period, making it a moving target that adapts to the actual working current conditions. This dynamic approach allows the protection circuit to accurately distinguish between normal current fluctuations and actual short circuits, significantly improving protection accuracy while maintaining reasonable circuit complexity through the use of standard delay circuit components.
Solution Approach 2:
The patent implements feedback by using the delayed detection voltage as a reference that continuously adapts to the actual working conditions. The comparison circuit constantly compares the real-time detection voltage with this dynamic reference, creating a feedback mechanism that self-adjusts to normal operating variations. This feedback loop enables the system to learn and adapt to the display device's actual current characteristics, improving measurement precision without requiring complex external calibration systems.
2Reliability
If the protection point is set too high, then the circuit is stable, but short-circuited devices may be missed and melted down
Solution Approach 1:
The dynamics principle resolves this contradiction by making the protection threshold adaptive rather than static. The reference voltage dynamically follows the working current profile through the delay circuit, automatically adjusting to the actual operating conditions. This ensures the protection point is neither too high (missing short circuits) nor too low (causing false trips), but precisely matched to the device's normal operating range, achieving both reliability and detection accuracy simultaneously.
Solution Approach 2:
The patent applies preliminary action by pre-delaying the detection voltage to create a reference that anticipates normal current variations before they occur. This preliminary processed reference voltage is ready to compare against incoming detection signals, allowing the system to proactively identify deviations from normal operation. The delay period is carefully selected to capture the transient behavior of normal startup and operation, enabling the circuit to distinguish these from abnormal short circuit conditions.
3Adaptability or versatility
If a fixed threshold is used, then the setting is simple, but it cannot adapt to current fluctuations and may cause wrong determinations
Solution Approach 1:
The patent implements self-service by enabling the protection circuit to automatically adapt to current fluctuations without external intervention. The delay circuit automatically generates a reference voltage that mirrors the working current's temporal characteristics, and the comparison circuit autonomously detects deviations. This self-adjusting mechanism eliminates the need for manual threshold setting and calibration, providing adaptability to various operating conditions while keeping the device complexity low through the use of standard delay and comparison components.
Data Source
AI summary
The present application discloses an over-current protection circuit, a driving method for the over-current protection circuit and a display device. The over-current protection circuit includes a detection circuit, a first protection branch and a comparison circuit; where the detection circuit detects the current of a preset detection point in real time and obtains a detection voltage based on the current passing through the detection point; the first protection branch includes a delayer which delays the detection voltage obtained by the detection circuit for a preset time and then outputs a first reference voltage; and the comparison circuit compares the detection voltage with the first reference voltage.