LED Driving Device Current Matching via Single Amplifier
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Solution Overview
Problem
In multi-channel LED driving schemes, the use of multiple amplifiers leads to increased current scattering due to unique offset voltage characteristics, reducing matching characteristics between channels and increasing chip size and production costs.
Innovation Solution
A light emitting diode (LED) driving device with a constant current driver and a minimum voltage selector that uses a single driving amplifier to maintain current levels across channels, along with buffers for PWM or AM control signals, and a multiplexer or amplifier for comparing voltage levels to select the minimum voltage for feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple amplifiers are used for each channel in multi-channel LED driving, then current control capability is improved, but current scattering increases due to unique offset voltage characteristics of each amplifier
Solution Approach 1:
The patent merges multiple amplifier functions into a single amplifier by combining the output signals of multiple channels through a summation node. This single amplifier approach eliminates the offset voltage variations that occur when using multiple separate amplifiers, thereby improving current matching characteristics across channels while maintaining current control capability.
Solution Approach 2:
The patent introduces an intermediary summation node that combines the feedback signals from multiple LED channels before processing them through a single amplifier. This intermediary structure allows the system to maintain individual channel control while using a unified amplification path, resolving the current scattering issue caused by multiple amplifiers with different offset characteristics.
2Reliability
If multiple amplifiers are used for each channel, then current control is achieved, but chip size increases
Solution Approach 1:
The patent combines multiple amplifier circuits into a single amplifier, significantly reducing the area occupied by amplification components on the chip. This merging approach maintains the necessary current control functionality while eliminating the space required for multiple separate amplifier blocks, thus reducing overall chip size.
Solution Approach 2:
The single amplifier in the patent serves multiple channels simultaneously by processing combined feedback signals from all channels. This multi-functional approach allows one amplifier to perform the work of multiple amplifiers, reducing component count and chip area while maintaining comprehensive current control across all LED channels.
3Reliability
If multiple amplifiers are used for each channel, then current control is achieved, but production cost increases
Solution Approach 1:
The patent merges multiple amplifier functions into a single amplifier circuit, reducing the total component count and simplifying the manufacturing process. This consolidation decreases production complexity, reduces the number of components that need to be tested and assembled, and lowers overall production costs while maintaining effective current control capability.
Solution Approach 2:
The patent discards the unnecessary multiple amplifier architecture and recovers the essential current control functionality through a more efficient single amplifier design. This approach eliminates the cost associated with manufacturing, testing, and assembling multiple amplifier components while preserving the core current control capability needed for multi-channel LED operation.
Data Source
AI summary
Disclosed herein is a light emitting diode (LED) driving device for driving a multi-channel LED element or an LED array for each channel, the LED driving device including: a constant current driver driving currents flowing in each channel; and a minimum voltage selector receiving voltage levels of each channel and selecting a minimum voltage level to thereby feedback the selected minimum voltage level to the constant current driver, wherein matching characteristics of currents flowing in each channel is improved and a size of an integrated circuit (IC) chip is also reduced as compared to a case according to the related art, thereby making it possible to reduce a production cost and satisfy the trend of miniaturization of the chip, while solving a performance deterioration problem due to deterioration of the matching of the currents between the channels.