LED Driving Circuit with Integrated Current Sensing
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Solution Overview
Problem
Existing LED driving circuits struggle to constantly control current through LEDs regardless of the on/off state of switching elements, especially in high-voltage environments, and require separate insulated sensors for accurate current detection, increasing system size and cost.
Innovation Solution
An LED driving circuit with a switching element, a sensing element generating feedback voltage, and a controller that controls the switching element based on this voltage to maintain constant current flow through the LED, eliminating the need for separate sensors by using a first inductor and diode to provide induced current during switching off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate insulated current sensor is added to detect LED current in high-voltage environment, then current detection accuracy is improved, but device complexity and system size increase
Solution Approach 1:
The patent merges the current detection function with the existing switching element and inductor circuit. The sensing resistor is integrated into the switching element's emitter, and the inductor's voltage across its terminals is utilized for current detection, eliminating the need for a separate insulated current sensor while maintaining accurate current measurement capability in high-voltage environments.
Solution Approach 2:
The inductor serves multiple functions: it provides current continuity during switching transitions and simultaneously enables current detection through its voltage across terminals. The switching element's emitter resistor serves both as a current-setting component and a sensing element, reducing the need for additional dedicated sensing components.
2Device complexity
If current detection is performed only when switching element is turned on, then circuit simplicity is maintained, but average current control precision deteriorates
Solution Approach 1:
The patent enables continuous current detection throughout the entire switching cycle rather than only during the on-state. By detecting current through the inductor's voltage across its terminals during both on and off states, the system maintains continuous feedback for average current control, improving precision without significantly increasing circuit complexity.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the voltage across the inductor terminals and using this information to adjust the switching element's operation. This feedback mechanism enables precise control of the average current flowing through the LED by comparing the detected current with the desired setpoint and adjusting duty cycle accordingly.
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
This solution allows for constant current control through LEDs regardless of switching element states, reduces system size and element count by omitting high-voltage insulation requirements, and directly detects and controls necessary voltages without additional sensing elements.
Implementation Method 1
a first inductor and a diode connected to the LED and configured to provide the LED with a current induced during the on operation if the switching element is turned off
Data Source
AI summary
Disclosed is a light-emitting diode (LED) driving circuit. The LED driving circuit includes a switching element configured to provide or interrupt input power to an LED, a first sensing element connected to the LED and configured to generate a feedback voltage corresponding to a current flowing through the LED, a controller having the same reference voltage as the first sensing element and configured to control an on/off operation of the switching element on the basis of the feedback voltage, and a first inductor and a diode connected to the LED and configured to provide the LED with a current induced during the on operation if the switching element is turned off.