LED Driving Circuit With Dual Current Paths for Thermal Control
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Solution Overview
Problem
LED driving circuits face thermal issues due to excess power dissipation, especially at high input voltages and low output voltages, leading to overheating and potential damage, while existing solutions like external resistors limit current flow and performance.
Innovation Solution
An LED driving circuit with dual current paths, including a first current path through a heat dissipation resistor and a second parallel path, controlled by a sensing circuit and control circuit to manage current distribution based on current sense signals, ensuring optimal current flow across varying input voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an external resistor is used to dissipate power and limit voltage across the IC, then thermal problems are solved, but the LED current is limited and the IC or LED may not work properly at low input voltages
Solution Approach 1:
The patent divides the current path into two separate paths: a first current path through the heat dissipation resistor for thermal management, and a second current path through a switch for providing additional current. This segmentation allows each path to serve its specific function independently, resolving the contradiction between thermal dissipation and current provision.
Solution Approach 2:
The patent uses a control circuit with a switch that can dynamically adjust the current distribution between the two paths based on operating conditions. The switch is controlled to be turned on or off according to the input voltage level, enabling the system to adaptively optimize both thermal management and current delivery across different operating ranges.
2Loss of energy
If the input voltage is high and the output voltage is low, then power dissipation increases causing overheating, but reducing voltage further limits the current available for LED operation
Solution Approach 1:
The patent segments the power delivery system into two parallel current paths, allowing the first path to handle voltage reduction and heat dissipation while the second path provides additional current capability. This segmentation enables the system to manage high power dissipation conditions without sacrificing available power for LED operation.
Solution Approach 2:
The control circuit acts as an intermediary that monitors the operating conditions and dynamically activates the second current path when needed. This intermediary component coordinates between the heat dissipation requirements and current delivery needs, optimizing the balance between power dissipation and available power across varying input voltage conditions.
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
The solution effectively manages thermal dissipation and maintains target current levels across a wide range of input voltages, preventing IC damage and ensuring consistent LED performance.
Implementation Method 1
The heat management of the LED driving circuit is an important issue especially when the input voltage is high and the output voltage is low. The excess power results in overheating of the LED driver
Implementation Method 2
The current sensing circuit is configured to sense a current sense signal representing a current flowing through the LED string
Data Source
AI summary
LED driving circuit includes a first current source, a second current source, a current sensing circuit, and a control circuit. The first current source, coupled in series with a heat dissipation resistor, provides a first current path to the LED string. The second current source, coupled in parallel with the serially coupled first current source and the heat dissipation resistor, provides a second current path to the LED string. The current sensing circuit is configured to sense a current sense signal representing a current flowing through the LED string. The control circuit is configured to control a current distribution of the first current path and a second current path in response to the current sense signal. When the current sense signal is greater than a threshold, a current flowing through the first current path is larger than a current flowing through the second current path.