Multi String LED Controller with Independent Current Regulation
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Solution Overview
Problem
Existing multi-channel LED driver designs face challenges in efficiently driving LEDs with different color temperatures and forward voltages, requiring separate current regulation while minimizing power-conversion components for cost-effectiveness.
Innovation Solution
A multiple channel current sharing controller with a constant buck regulator and feedback loop is designed to regulate current for each LED string independently, using a single set of power components and minimizing power conversion components, ensuring efficient current sharing and transient immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate current regulation is implemented for each LED channel, then independent current control is achieved, but the number of power-conversion components increases significantly
Solution Approach 1:
The patent merges multiple power conversion functions into a single shared power conversion unit. Instead of having separate power conversion circuits for each LED channel, one power conversion unit generates a shared output current that is then distributed to multiple LED channels through current regulation circuitry, dramatically reducing the number of power-conversion components while maintaining independent control capability
Solution Approach 2:
The patent segments the current regulation function from the power conversion function. The power conversion unit operates as a single integrated block, while the current regulation for each channel is handled by separate control circuitry that modulates the shared output current, allowing independent channel control without duplicating power conversion components
2Device complexity
If all output channels share the same regulation, then device complexity is reduced, but independent current control is lost
Solution Approach 1:
The patent segments the control function from the power conversion function. Each LED channel has its own current regulation circuitry that independently controls the shared power conversion output, enabling different current settings for each channel while using a single power conversion unit
Solution Approach 2:
The patent introduces an intermediary current regulation stage between the shared power conversion unit and the LED channels. This intermediary layer allows the single power conversion output to be independently regulated for each channel, acting as a mediator that provides both shared efficiency and independent control
3Ease of operation
If control MOSFET/Transistor operates in linear region, then current control is simplified, but efficiency decreases
Solution Approach 1:
The patent employs periodic switching action of the MOSFET/Transistor in the power conversion unit, operating it as a switch-mode device rather than in the linear region. The device switches on and off periodically to transfer energy, dramatically reducing power loss while maintaining effective current control through duty cycle modulation
Solution Approach 2:
The patent changes the operating parameter of the MOSFET/Transistor from continuous linear region operation to periodic switching operation. By changing the duty cycle of the switching action, the patent achieves current control while maintaining the device in a high-efficiency switch-mode state rather than a dissipative linear state
Data Source
AI summary
A multi string controller with independent current setting for each string is designed for solid state lighting applications. This controller can regulate multiple channels of LEDs. Each string may have a different forward voltage and current setting. A constant buck regulator is also integrated inside this controller to regulate the total current, which is fed into the LED output channels. The circuit also contains a feedback loop in order to precisely control the current passing through each string and is immune to transient conditions.