LED Driver Standby Mode via Bus Voltage Feedback Control
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Solution Overview
Problem
Existing driver devices for semiconductor light-emitting devices face challenges in minimizing power consumption during standby mode while preventing unintended glowing, particularly due to complex and costly circuit architectures that require multiple transformers and power supplies.
Innovation Solution
A driver device with a first and second stage switched-mode power supply, a voltage feedback arrangement, and a controller that changes the feedback signal representation to lower the bus voltage during standby mode, ensuring zero output current and reducing energy dissipation in voltage regulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a parallel power supply with an additional transformer is used to keep the processor operational during standby mode, then the processor can remain active and quickly resume normal operation, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent merges the standby power supply function into the existing primary power supply circuit by utilizing the same transformer and power conversion components. The controller selectively powers down the LED driving circuitry while maintaining processor operation through the same power infrastructure, eliminating the need for a separate parallel power supply and its additional transformer.
Solution Approach 2:
The primary power supply is designed to serve dual functions: fully powering the LED driver during normal operation and providing reduced power for processor operation during standby mode. This multi-functionality is achieved through selective circuit switching and voltage regulation that allows the same power components to support different operational states without requiring dedicated standby power infrastructure.
2Use of energy by stationary object
If residual current is allowed to flow through the LEDs during standby mode, then power consumption is reduced, but the LEDs may glow unintentionally which is disadvantageous in dark environments
Solution Approach 1:
The patent implements dynamic control of the LED current during standby mode by continuously monitoring the LED forward voltage and adjusting the current level accordingly. The controller dynamically sets the current to a threshold level that prevents visible glowing while consuming minimal power, rather than using a fixed current level. This dynamic adjustment allows the system to adapt to different LED characteristics and environmental conditions.
Solution Approach 2:
The system uses feedback control by measuring the actual current flowing through the LEDs and comparing it against a predetermined threshold. The controller adjusts the current level based on this feedback to maintain it below the glowing threshold while minimizing power consumption. This closed-loop control ensures that the LEDs remain dark during standby mode without requiring complete power shutdown.
3Reliability
If the bus voltage is maintained at normal operating levels during standby mode, then the processor and control circuits can operate reliably, but power consumption increases and energy is wasted
Solution Approach 1:
The patent changes the bus voltage parameter from normal operating levels to a reduced standby level by modifying the feedback signal that controls the power converter. The controller adjusts the feedback signal to indicate a lower target voltage to the power conversion circuitry, causing the bus voltage to automatically settle at a reduced level suitable for low-power processor operation. This parameter change propagates through the power distribution network, reducing power consumption across all voltage rails simultaneously.
Solution Approach 2:
The system uses the voltage feedback signal as a control mechanism to regulate bus voltage levels. During standby mode, the controller modifies this feedback signal to convey information about the desired reduced voltage level to the power converter. The converter responds to this feedback by adjusting its output to maintain the new voltage level, creating a self-regulating system that automatically maintains appropriate voltage levels for standby operation without requiring manual intervention or complex voltage switching circuitry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables low-power standby mode operation without glowing, simplifying the circuit architecture and reducing manufacturing costs by minimizing the need for multiple transformers and power supplies, while ensuring quick resumption of normal operation.
Implementation Method 1
a voltage feedback arrangement configured to convey a feedback signal representing said bus voltage to a control circuit of said first stage switched-mode power supply
Implementation Method 2
a first stage switched-mode power supply configured to produce a bus voltage, a second stage switched-mode power supply configured to utilize said bus voltage to produce an output current
Data Source
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AI summary
A driver device provides output current to at least one semiconductor light-emitting device. It comprises a first stage switched-mode power supply (103) configured to produce a bus voltage (Vbus), and a second stage switched-mode power supply (104) configured to utilize said bus voltage to produce an output current to be led to said at least one semiconductor light-emitting device. A voltage feedback arrangement is configured to convey a feedback signal representing said bus voltage to a control circuit (105) of said first stage switched-mode power supply (103). A controller is capable of setting the driver device into a standby mode in which said output current is essentially zero. Said controller is configured to change the way in which said feedback signal represents said bus voltage as a part of setting the driver device into said standby mode, for lowering the bus voltage.