Sequential Linear LED Driver Commutation Circuit
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Solution Overview
Problem
Current sequential linear LED driver circuits experience spikes or gaps in line current due to improper timing of current commutation between current sinks, leading to excess electromagnetic interference (EMI).
Innovation Solution
A circuit design where all current sink currents pass through a summing node, facilitating smooth commutation without relying on voltage measurements, thereby avoiding spikes and gaps in line current, and eliminating the need for costly high-voltage measurement and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current commutation between current sinks is performed without proper timing coordination, then the LED string can be driven with varying segments, but spikes and gaps occur in the line current causing excess EMI
Solution Approach 1:
The patent merges all current sink currents through a common summing node, ensuring that the sum of currents remains continuous and constant. This combining approach eliminates the spikes and gaps that occur when current sinks commute independently, thereby reducing electromagnetic interference while maintaining adaptability in LED string utilization.
Solution Approach 2:
The patent employs a feedback mechanism where the summing node monitors the combined current from all current sinks and uses this information to coordinate commutation timing. This feedback ensures smooth transitions between current sinks by adjusting their operation based on the actual current sum, preventing EMI-causing disruptions in the line current.
2Reliability
If voltage measurement and processing is used to coordinate current commutation, then commutation timing can be controlled, but costly high-voltage measurement and processing is required
Solution Approach 1:
The patent introduces a summing node as an intermediary that directly combines current sink currents without requiring voltage measurement. This intermediary provides the necessary commutation coordination information through current summation alone, eliminating the need for complex and costly high-voltage measurement and processing circuits while maintaining reliable timing control.
3Device complexity
If current sinks operate independently without coordination, then circuit complexity is reduced, but spikes and gaps in line current occur causing EMI
Solution Approach 1:
The patent combines all current sink currents through a single summing node, creating a unified current path. This merging approach provides simple coordination without complex control circuits, as the summing node inherently ensures continuous current summation. The result is reduced EMI from line current disruptions while maintaining relatively simple circuit architecture.
Data Source
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AI summary
A sequential linear LED driver circuit is provided. The sequential linear LED driver circuit may include a plurality of current sinks (100,105,110,115), wherein each of the plurality of current sinks (100,105,110,115) is configured to be coupled to a segment (SEG1,SEG2,SEG3,SEG4) of a string of light-emitting diodes (LEDs), and a voltage divider (120) that generates a plurality of reference voltages (VREF1,VREF2,VREF3,VREF4), wherein each of the plurality of reference voltages (VREF1,VREF2,VREF3,VREF4) is applied to a respective current sink of the plurality of current sinks (100,105,110,115). The output of each current sink of the plurality of current sinks (100,105,110,115) may be connected at a summing node (CS).