LED Driver Variable Reference Voltage Efficiency
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Solution Overview
Problem
Conventional LED driver systems are inefficient due to the use of fixed output voltage and linear regulators, resulting in significant power losses, with the worst-case efficiency typically around 65%.
Innovation Solution
A compact and efficient LED driver system that uses a power converter with a variable reference voltage and a binary-weighted transistor array to dynamically control current through LED strings, allowing for fast slew rates and programmable current pulses, reducing the size and cost of the system while achieving high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a linear regulator with a fixed reference voltage is used to drive LED strings, then the circuit structure is simple, but the power efficiency is low (around 65% at worst case)
Solution Approach 1:
The patent replaces the fixed reference voltage with a dynamic reference voltage that changes based on the LED string being driven. The reference voltage is generated by a voltage divider network that can be reconfigured to provide different voltage levels, allowing the power converter to operate at optimal efficiency across different LED strings with different forward voltages.
Solution Approach 2:
The patent changes the operating parameters of the power converter by implementing a variable reference voltage that adapts to different LED strings. This allows the converter to adjust its output characteristics dynamically, improving efficiency by matching the reference voltage to the specific LED string requirements rather than using a fixed reference voltage.
2Adaptability or versatility
If a separate linear regulator is used for each LED string, then each string can be controlled independently, but the device size and cost increase
Solution Approach 1:
The patent implements a single power converter that can serve multiple LED strings by dynamically reconfiguring its reference voltage. The voltage divider network and multiplexer allow the same converter circuit to be shared across multiple strings, eliminating the need for separate regulators while maintaining independent control capability.
Solution Approach 2:
The patent merges multiple separate regulator functions into a single power converter by combining the voltage reference generation and conversion functions. The voltage divider networks for different strings are merged into a single reconfigurable reference voltage system that feeds the power converter, reducing component count and device size.
3Device complexity
If a fixed output voltage is used in the power converter, then the circuit is simpler, but large power losses occur due to voltage overhead requirements
Solution Approach 1:
The patent implements a dynamic reference voltage system that allows the power converter to adapt its output characteristics. The voltage divider network can be reconfigured to provide different reference voltages matching the LED string forward voltages, eliminating the need for fixed high voltage overhead and reducing power losses in the pass transistor.
Data Source
AI summary
A method includes receiving a variable reference voltage at a power converter and generating a regulated output voltage based on the variable reference voltage. The method also includes sequentially driving multiple sets of light emitting diodes (LEDs) using the regulated output voltage, where each set includes at least one LED. The variable reference voltage varies based on the set of LEDs being driven. For example, the method could include receiving a first reference voltage, generating a first output voltage based on the first reference voltage, and driving a first set of LEDs using the first output voltage. The method could then include receiving a second reference voltage, generating a second output voltage based on the second reference voltage, and driving a second set of LEDs using the second output voltage. At least one additional set of LEDs could be driven concurrently with the sequential driving of the multiple sets of LEDs.