Voltage Converter Current Mirror Sensing for Display Overcurrent
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Solution Overview
Problem
Display devices face issues with overcurrent sensing, as existing methods require additional power consumption from sensing resistors and are affected by external temperature changes.
Innovation Solution
A voltage converter and display device design that senses overcurrent without a sensing resistor, utilizing an inductor, transistors, and a current mirror circuit to mirror currents, with a gate electrode of the third transistor connected to a reference terminal, allowing for efficient current sensing and reduced temperature sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensing resistor is used to sense overcurrent, then overcurrent detection is enabled, but additional power is consumed by the sensing resistor
Solution Approach 1:
The patent extracts the sensing function from a traditional sensing resistor and implements it using a dedicated sensing transistor (third transistor) with a current mirror circuit. This separation allows the sensing element to operate with minimal power consumption while maintaining accurate overcurrent detection capability through the transistor's inherent electrical characteristics and the current mirror's replication function.
Solution Approach 2:
The sensing transistor utilizes the existing current flow through the first transistor to generate the sensing signal, rather than requiring an separate power source for the sensing resistor. The current mirror circuit automatically replicates the sensing current without additional power consumption, allowing the sensing mechanism to serve itself using the operational currents already present in the circuit.
2Measurement precision
If a sensing resistor is used for overcurrent sensing, then current measurement is achieved, but the system becomes sensitive to external temperature changes
Solution Approach 1:
The patent replaces the passive resistive sensing mechanism with an active transistor-based sensing system. The sensing transistor and current mirror circuit use electrical field effects rather than resistive heating effects, making the sensing mechanism inherently less sensitive to temperature variations that affect resistor characteristics. The transistor's gate-controlled operation provides temperature-stable current sensing.
Solution Approach 2:
The patent changes the sensing parameter from resistance (which is temperature-dependent) to transistor gate voltage and current mirror ratio (which are more temperature-stable). By controlling the sensing through voltage parameters rather than resistance parameters, the system achieves current sensing that is substantially unaffected by external temperature changes.
3Measurement precision
If additional components like sensing resistors are added, then overcurrent sensing capability is provided, but device complexity increases
Solution Approach 1:
The patent merges the sensing function with the existing power conversion circuitry by using the sensing transistor in conjunction with the current mirror circuit that is already part of the voltage converter architecture. This integration allows overcurrent sensing to be achieved without adding completely separate sensing components, thereby reducing overall device complexity while maintaining sensing capability.
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
Enables overcurrent sensing without power consumption by sensing resistors and minimizes the impact of external temperature changes, improving the reliability and efficiency of display devices.
Implementation Method 1
a current mirror circuit that mirrors currents flowing through the second node, the third node, and a sensing terminal
Data Source
AI summary
An embodiment of the present disclosure provides a voltage converter including: an inductor in which a first electrode thereof receives an input voltage and a second electrode thereof is connected to a first node; a first transistor in which a first electrode thereof is connected to the first node and a second electrode thereof is connected to a second node providing an output voltage; a second transistor in which a first electrode thereof is connected to the first node and a second electrode thereof is connected to a reference terminal; and a current sensor connected to the first node and the second node, wherein the current sensor includes: a third transistor in which a first electrode thereof is connected to the first node and a second electrode thereof is connected to a third node; and a current mirror circuit that mirrors currents flowing through the second node, the third node, and a sensing terminal.