LED Voltage Selection Circuit for Minimum Output Detection
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Solution Overview
Problem
Detecting and selecting the minimal output voltage from multiple parallel light emitting diode (LED) channels is challenging due to varying voltage drops across each channel, making it difficult to determine the appropriate feedback voltage for driving the LEDs effectively.
Innovation Solution
A voltage selection circuit utilizing a plurality of operation amplifiers with a positive input terminal receiving remainder voltages from LED channels, an output terminal for outputting the minimum voltage, and an output stage with stronger current sinking ability than sourcing ability, connected to generate a PWM signal and drive voltage through a DC-to-DC converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple LED channels are disposed in parallel to increase lighting capacity, then the lighting output is improved, but the difficulty of detecting and selecting the minimal output voltage increases
Solution Approach 1:
The patent introduces an operational amplifier as an intermediary device to detect and compare the output voltages of multiple parallel LED channels. The operational amplifier acts as a mediator that automatically identifies the minimal voltage among multiple channels through voltage comparison, eliminating the need for complex external measurement circuits and solving the detection difficulty inherent in parallel LED configurations.
Solution Approach 2:
The patent implements a feedback mechanism where the detected minimal output voltage is fed back to the driving circuit to regulate the operating current of all LED channels. This feedback loop ensures that the driving current is adjusted based on the actual minimal voltage condition, enabling precise control and preventing over-driving of any individual LED channel in the parallel configuration.
2Power
If the output stage of operation amplifiers has stronger current sourcing ability to drive the PWM signal, then the signal driving capability is improved, but the voltage selection precision deteriorates
Solution Approach 1:
The patent divides the output stage of the operational amplifier into two separate functional parts: a voltage comparison function and a current driving function. The voltage comparison function precisely identifies the minimal voltage threshold, while the current driving function generates the PWM signal with sufficient driving capability. This segmentation allows each function to optimize its performance without compromising the other.
Solution Approach 2:
The patent introduces an intermediate buffer stage between the voltage comparison output and the PWM generation circuit. This intermediary buffer provides current amplification to enhance the driving capability of the PWM signal while maintaining the precision of the voltage selection made by the operational amplifier's comparison function.
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 precise detection and selection of the minimum voltage from LED channels, allowing for more accurate adjustment of driving voltage, improving the operational status and efficiency of LED channels.
Implementation Method 1
Each of the first operation amplifiers has: a positive input terminal receiving one of the remainder voltages from one of the first ends of the light emitting diode channels; an output terminal for outputting the minimum voltage
Implementation Method 2
a DC-to-DC voltage converter for generating a driving voltage on the second ends of the light emitting diode channels according to the PWM signal
Implementation Method 3
The light emitting diodes (LEDs) are estimated to be four times as efficient as conventional incandescent lights
Data Source
AI summary
A voltage selection circuit selecting a minimum voltage from the remainder voltages outputted from the light emitting diode channels is disclosed. The voltage selection circuit includes a first picking circuit, which has the first operation amplifiers, a positive input terminal, an output terminal, a negative input terminal, and an output stage. Each of the first operation amplifiers includes a positive input terminal, an output terminal, a negative input terminal, and an output stage. The positive input terminal receives one of the remainder voltages from one of the first ends of the light emitting diode channels. The output terminal outputs the minimum voltage, in which the output terminals of the first operation amplifiers are connected together. The negative input terminal is electrically connected to the output terminal. The output stage is electrically connected to the output terminal, in which the output stage has current sinking ability stronger than current sourcing ability.