Push-Pull Load Driving Circuit for Small Short-Circuit Detection
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Solution Overview
Problem
Current display panel technologies face challenges in accurately and sensitively detecting abnormalities, such as small-scale short circuits, in the output current to the data lines, which can lead to increased device size and cost due to the use of resistors and comparators for detection.
Innovation Solution
A load driving circuit with a push-pull output-stage and a detection circuit that generates mirror currents to detect changes in output current, using a coupling circuit to produce voltages indicative of normal or abnormal conditions, allowing for quick and accurate detection without increasing device scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistors and comparators are used for detecting output current abnormalities, then detection sensitivity is improved, but device size and cost increase
Solution Approach 1:
The patent extracts the detection function from traditional resistor-comparator circuits and implements it using only transistors already present in the push-pull output stage. By utilizing the existing Q1 and Q2 transistors to generate mirror currents, the design eliminates the need for additional resistors and comparators, thereby maintaining detection sensitivity while reducing device size and component count.
Solution Approach 2:
The transistors in the push-pull output stage serve dual functions: they act as both the output driving elements and the detection elements. The same transistors (Q1, Q2) that drive the load also generate the mirror currents used for abnormality detection, eliminating the need for separate detection components and reducing overall device complexity.
2Measurement precision
If resistors and comparators are used for detecting output current abnormalities, then detection sensitivity is improved, but device cost increases
Solution Approach 1:
The patent removes expensive resistors and comparators from the detection circuit and replaces them with transistors that are already part of the output stage. This extraction of unnecessary components directly reduces manufacturing cost while maintaining the ability to detect output current abnormalities through mirror current comparison.
Solution Approach 2:
The patent uses transistors, which are standard, low-cost components in integrated circuits, instead of more expensive resistors and comparators. The transistor-based mirror current generation provides a cost-effective solution that achieves the same detection functionality using inexpensive, easily manufacturable components.
3Device complexity
If traditional detection circuits are used, then device size is reduced, but detection accuracy for small-scale short circuits deteriorates
Solution Approach 1:
The detection circuit serves itself by using the output stage transistors to generate the detection signals. The mirror currents are generated directly from the output transistors' own currents, creating a self-contained detection system that maintains high accuracy for small-scale short circuits without requiring external or additional components that would increase device size.
Data Source
AI summary
Provided is an output amplifier having: a push-pull output-stage formed by first and second output-stage transistors; and a detection circuit detecting an abnormal output current output by the output amplifier and including: a coupling circuit, generating first and second currents mirroring current flowing in the first output-stage transistor and third and fourth currents mirroring current flowing in the second output-stage transistor, coupling the first and third currents at a first output node, outputting a first voltage at the first output node, coupling the second and fourth currents at a second output node, and outputting a second voltage at the second output node; and a determination circuit, outputting a determination signal indicating normality of an output current based on the first and second voltages. The coupling circuit generates the first to fourth currents. In the reference state, the third current >the first current, the second current >the fourth current.