LED Driving Circuit with Adaptive Voltage Selection
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Solution Overview
Problem
Existing driving circuits for light emitting elements face inefficiencies in providing the required driving voltage, leading to increased current consumption and circuit area due to the need for multiple terminals and voltage boosting methods.
Innovation Solution
A monolithically integrated driving circuit with multiple switches and constant current sources that selectively output voltage between the battery voltage and boosted voltage, controlled by a circuit that monitors and adjusts voltage levels to optimize efficiency and reduce terminal count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a switching regulator or charge pump circuit is used to boost battery voltage for driving LEDs, then the required driving voltage can be obtained, but current consumption increases and circuit area increases
Solution Approach 1:
The patent applies dynamics by making the voltage supply flexible and adaptive. Multiple switches dynamically select between battery voltage and boosted voltage based on real-time LED forward voltage requirements. This dynamic adaptation allows the circuit to use the minimum necessary voltage, reducing unnecessary current consumption while maintaining the required driving voltage for LED operation.
Solution Approach 2:
The patent changes the voltage parameter dynamically by switching between two voltage levels (battery voltage and boosted voltage). The control circuit monitors LED forward voltage and adjusts the supply voltage parameter accordingly, using boosted voltage only when necessary and battery voltage when sufficient, thereby optimizing energy efficiency while maintaining adequate driving voltage.
2Reliability
If constant current sources are provided on the cathode side of LEDs, then proper current control is achieved, but the number of terminals increases and circuit area increases
Solution Approach 1:
The patent inverts the conventional approach by placing constant current sources on the anode side instead of the cathode side of LEDs. This inversion allows the current control function to be integrated into the existing terminal structure, avoiding the need for additional terminals while maintaining reliable current control for each LED.
Solution Approach 2:
The patent merges the constant current source function with the anode terminal structure. By combining these functions at the anode side, the circuit achieves current control without adding separate terminal connections, thereby reducing the overall circuit area while maintaining reliable current regulation for each LED.
Data Source
AI summary
Multiple LED terminals are provided to multiple LEDs, respectively. Each of these LED terminals is connected to the anode of the corresponding LED. A booster circuit boosts an input voltage. Multiple constant current sources are provided to the multiple LEDs, respectively. One terminal of each of the constant current sources is connected to the corresponding one of the LEDs via the corresponding one of the LED terminals. Multiple switches are provided to the multiple constant current sources, respectively, each of which selectively outputs a voltage selected from the input voltage and the output voltage of the booster circuit to the corresponding constant current source. A control circuit monitors each of the voltages at the multiple LED terminals, and controls the connection state of each of the switches based upon the corresponding voltage.