Symmetric LED Driver Circuit Layout for Current Matching
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Solution Overview
Problem
Existing LED display driver chips with multi-channel constant current output architecture suffer from poor current consistency in rows and columns of LED dot matrices, affecting display quality due to mismatch and noise issues.
Innovation Solution
An LED driver circuit design with symmetrically distributed driving channel groups, each comprising common-source and common-gate device modules, electrostatic protection, operational amplifiers, and blanking modules, connected via metal wires to an analog ground pad, reducing internal noise and improving current matching accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-channel constant current output architecture is used to drive large number of LEDs, then driving capability is improved, but current consistency between rows and columns deteriorates
Solution Approach 1:
The driver chip is divided into multiple independent driving channels, each with its own constant current source. The chip is further segmented into first and second component areas with symmetrically distributed driving channel groups, allowing independent optimization of each segment's current characteristics while maintaining overall system capability to drive large numbers of LEDs.
Solution Approach 2:
The patent employs asymmetric current consistency compensation by introducing different compensation currents for rows and columns. The current consistency compensation module provides asymmetric compensation to counterbalance the systematic differences between row and column currents, thereby improving overall current consistency across all LED channels.
2Shape
If driving channels are symmetrically distributed in component areas, then layout balance is improved, but internal noise and device mismatch deteriorate
Solution Approach 1:
The patent extracts the ground reference function from the signal transmission paths by introducing a dedicated analog ground pad in the second component area. This separate ground reference is connected through metal wires to provide a stable voltage reference for all driving channels, removing ground noise from the signal paths and reducing internal noise interference.
Solution Approach 2:
The patent implements equipotential grounding by connecting multiple ground points across the chip to a common analog ground pad through metal wires. This creates equipotential zones that minimize ground loops and voltage differences, reducing internal noise and improving signal integrity despite the symmetric distribution of driving channels.
Data Source
AI summary
Disclosed in an embodiment of the present application is an LED driver circuit and an LED display apparatus. The LED driver circuit comprises: a first component area, which comprises a first driving channel group and a second driving channel group that are arranged symmetrically and comprise a same number of driving channels, respectively; and a second component area, which is provided with an analog ground pad connected to a substrate of the driving channels through a metal wire. According to the present application, chip internal noise can be effectively reduced, and accuracy of matching output currents of the driving channels can be improved to obtain good current consistency, thereby being beneficial to guarantee display effect of a LED display screen.