LED Driving Circuit Single Comparator Overvoltage Protection
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Solution Overview
Problem
Existing LED driving circuits using the linear method require complex feedback circuits with multiple error amplifiers, increasing manufacturing costs and susceptibility to malfunctions due to the need for overvoltage protection and voltage regulation.
Innovation Solution
A simplified driving circuit configuration utilizing a single comparator to detect overvoltages and implement an integrated circuit, which includes a DC/DC converter, LED groups, current sources, voltage detection, minimum voltage detection, and PWM control, reducing the number of components and facilitating cost-effective manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple error amplifiers are used in the feedback circuit, then overvoltage protection and voltage regulation are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple error amplifiers into a single error amplifier by integrating the overvoltage detection function directly into the feedback circuit. The error amplifier compares the divided output voltage with a reference voltage and generates an error signal that controls the switching element, eliminating the need for separate overvoltage protection circuits while maintaining protection functionality.
Solution Approach 2:
The error amplifier serves multiple functions simultaneously: it performs voltage regulation by comparing the divided output voltage with the reference voltage, generates error signals for PWM control, and provides overvoltage protection. This multi-functional design reduces the number of components while maintaining comprehensive protection and regulation capabilities.
2Manufacturing precision
If multiple error amplifiers are used in the feedback circuit, then voltage regulation is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges multiple error amplifiers into a single error amplifier that performs all voltage regulation functions. This reduction in component count directly lowers manufacturing costs while maintaining precise voltage regulation through the error amplifier's comparison of divided output voltage with reference voltage and generation of appropriate error signals.
3Measurement precision
If multiple error amplifiers are used in the feedback circuit, then overvoltage detection is improved, but reliability decreases due to more components
Solution Approach 1:
The patent combines overvoltage detection functionality into the single error amplifier circuit, reducing the total number of components. The error amplifier detects overvoltage conditions by comparing the divided output voltage with the reference voltage and adjusts the PWM duty cycle accordingly, maintaining detection precision while improving overall circuit reliability through component reduction.
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 reduces manufacturing costs and simplifies the circuit design by using a single comparator to detect overvoltages, enabling efficient voltage regulation and protection while integrating key components into a single IC, thus enhancing reliability and reducing component count.
Implementation Method 1
a DC/DC converter converting an input DC voltage into an output DC voltage according to a voltage control signal
Implementation Method 2
a light emitting device block including a plurality of LED groups connected in parallel to an output terminal of the DC/DC converter
Implementation Method 3
a single comparator including a first non-inverting input terminal receiving the voltage detected by the voltage detection unit, a second non-inverting input terminal receiving the minimum voltage detected by the minimum voltage detection unit, and an inverting input terminal receiving a predetermined reference voltage
Data Source
AI summary
There is provided a driving circuit of a light emitting device. The driving circuit of a light emitting may include: a DC/DC converter converting an input DC voltage into an output DC voltage; a light emitting device block including a plurality of LED groups connected to an output terminal of the DC/DC converter; a current source circuit unit including a plurality of current sources; a voltage detection unit detecting the output DC voltage of the DC/DC converter; a minimum voltage detection unit detecting a minimum voltage among a plurality of voltages between the plurality of LED groups and the plurality of current sources, respectively; and a single comparator including a first non-inverting input terminal receiving the voltage detected by the voltage detection unit, a second non-inverting input terminal receiving the minimum voltage detected by the minimum voltage detection unit, and an inverting input terminal receiving a predetermined reference voltage.