LED Driver Voltage Detection Using Low-Voltage Comparator Isolation
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Solution Overview
Problem
Existing methods for detecting the output voltage of LED driving devices using constant current sources face inaccuracies due to high voltage levels, which can damage comparators and introduce significant input offset errors, especially when dealing with multiple LEDs connected in series.
Innovation Solution
A voltage detecting device utilizing low voltage elements, comprising a voltage inspecting device, an isolating/connecting control device, and a comparing device, where the comparing device is composed of low voltage elements and is isolated from high voltage levels to prevent damage and minimize offset errors, allowing accurate voltage comparison with a reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage elements are used to realize the comparator for detecting output voltage of LED driving device, then the comparator can handle high voltage levels from series-connected LEDs, but the area of the circuitry increases and input offset voltage increases
Solution Approach 1:
The patent introduces a voltage dividing circuit as an intermediary between the high voltage output terminal and the comparator. This mediator circuit safely steps down the high voltage to a level suitable for the comparator, eliminating the need for high-voltage rated comparator components while maintaining accurate detection capability.
Solution Approach 2:
The patent changes the voltage parameter level by using a voltage dividing circuit to transform the high voltage output into a scaled-down version. This parameter transformation allows the use of low-voltage comparator elements while still accurately reflecting the high voltage state, thereby reducing circuit area and offset voltage.
2Reliability
If voltage division is used to reduce voltage level for comparator input, then low voltage elements can be used, but the input offset error is enlarged by the voltage division ratio
Solution Approach 1:
The patent segments the voltage detection function into two independent parts: a voltage dividing circuit for level reduction and a comparator for voltage comparison. This segmentation allows each component to be optimized independently, with the voltage divider using precise resistance values and the comparator using low-voltage elements, thereby maintaining accuracy while reducing offset errors.
Solution Approach 2:
The patent creates a voltage-copied version through the dividing circuit that maintains the same voltage relationship characteristics as the original high voltage output. By copying the voltage state proportionally, the system can use low-voltage comparator elements while preserving the accuracy of voltage detection, as the copied voltage maintains the same relative relationships.
3Reliability
If resistance division is used to reduce voltage, then voltage level is reduced for comparator, but error caused by resistance mismatch is enlarged
Solution Approach 1:
The patent uses a voltage dividing circuit as an intermediary that is specifically designed with precision resistance values. This mediator circuit is configured to provide accurate voltage reduction while minimizing the impact of resistance mismatch, thereby maintaining voltage detection accuracy even when using low-voltage comparator elements.
Data Source
AI summary
A voltage detecting device applied to a driving device of a light-emitting diode device is provided. The detecting device includes a voltage inspecting device, an isolating/connecting control device and a comparing device. The voltage inspecting device is coupled to an output terminal of the driving device to inspect a status of an output voltage of the driving device and outputs an inspecting signal. The isolating/connecting control device, coupled between the voltage inspecting device and the driving device, isolates or connects the output terminal of the driving device according to the inspecting signal. The comparing device, composed of low voltage elements, is coupled to the isolating/connecting control device, and compares the output voltage of the driving device with a reference voltage and generates a detecting signal according to the comparing result.