Multi-String LED Array Current Regulation with Internal and External Limiters
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Solution Overview
Problem
Existing systems for controlling light emitting diode (LED) arrays face challenges in efficiently regulating currents across multiple LED strings, leading to thermal issues and increased heat dissipation in system controller ICs, while also requiring a low pin-count for system controller ICs.
Innovation Solution
The implementation of internal and external current limiter circuits, where internal circuits perform partial current regulation and external circuits provide additional regulation based on the operating range of internal circuits, using a common drive signal to maintain a low pin-count and reduce thermal dissipation in the system controller IC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal current limiter circuits are used to regulate current through each LED string, then current regulation is achieved, but thermal dissipation in the system controller IC increases
Solution Approach 1:
The current regulation function is segmented between internal current limiter circuits within the system controller IC and external current limiter circuits. The internal circuits handle basic regulation while external circuits provide additional regulation capability, dividing the thermal load and allowing the internal circuits to operate in a more efficient linear region without excessive heat generation.
Solution Approach 2:
External current limiter circuits are introduced as intermediary components between the system controller IC and the LED strings. These external circuits act as mediators that perform additional current regulation, reducing the burden on internal circuits and thereby reducing thermal dissipation in the system controller IC while maintaining reliable current regulation.
2Reliability
If multiple external current limiter circuits are used for each LED string, then current regulation is improved, but device complexity increases
Solution Approach 1:
Multiple external current limiter circuits are configured to be controlled by a single common drive signal, making them functionally equivalent and interchangeable. This universal control approach simplifies the overall system complexity despite having multiple external circuits, as they all respond identically to the same control signal and can serve multiple LED strings collectively.
3Adaptability or versatility
If individual control signals are provided to each external current limiter circuit, then selective control is achieved, but pin-count of system controller IC increases
Solution Approach 1:
Multiple individual control signals for external current limiter circuits are merged into a single common drive signal. This common signal is distributed to multiple external current limiter circuits, allowing them to be controlled collectively rather than individually. This merging approach maintains the ability to control LED string intensity while significantly reducing the pin-count requirement of the system controller IC.
Data Source
AI summary
Apparatus, systems, and methods related to controlling multiple strings of light emitting diodes (LEDs) are disclosed. An apparatus may include internal current limiter circuits that are each coupled in series with an associated string of LEDs and are configured to at least partially regulate the current through the associated string of LEDs. The apparatus may also be configured to control external current limiter circuits that are each coupled in series with a corresponding internal current limiter circuit and the string of LEDs associated with the corresponding internal current limiter circuit.