LED Supply Circuit with Digital Feedback Control
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Solution Overview
Problem
Conventional supply circuits for light-emitting elements, such as LEDs, face inefficiencies due to fixed voltage supply, leading to variable current flow and potential under or over-power consumption, especially in battery-powered portable applications.
Innovation Solution
A control concept utilizing a voltage regulator with feedback from a voltage divider to adjust output voltage and current through a series resistor, ensuring a desired current flow and sufficient voltage for the light-emitting element, employing a control block with an analog-to-digital converter and digital-to-analog converter to dynamically regulate the voltage based on feedback values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed voltage higher than the nominal forward voltage is supplied to the light-emitting element, then the forward voltage is reliably achieved, but the current through the element varies and unnecessary power is consumed in the series resistor
Solution Approach 1:
The patent implements a feedback mechanism where the voltage at the second terminal (voltage across the series resistor) is converted to a digital feedback value by an ADC, compared with a reference feedback value by a control element, and the result is used to adjust the control value for the DAC. This closed-loop feedback system dynamically adjusts the output voltage to optimize power consumption while ensuring the light-emitting element receives sufficient voltage to operate reliably.
Solution Approach 2:
The patent transitions from a fixed voltage supply to a dynamic voltage regulation system. The control element (microcontroller) continuously monitors the voltage feedback value and adjusts the control value sent to the DAC in real-time, making the supply voltage adaptive rather than static. This dynamic adjustment allows the system to optimize power consumption based on actual operating conditions while maintaining reliable operation of the light-emitting element.
2Adaptability or versatility
If the actual forward voltage differs depending on the component, then component variability is accommodated, but the current through the element set via a series resistor varies
Solution Approach 1:
The feedback mechanism measures the actual voltage across the series resistor (which reflects the actual current flow) and uses this information to adjust the output voltage. By continuously monitoring and adjusting based on real measurements, the system compensates for component variability and maintains consistent current through the light-emitting element despite differences in actual forward voltage between components.
Solution Approach 2:
The patent changes the supply voltage parameter dynamically based on the measured feedback value. The control element adjusts the control value for the DAC according to the comparison between the voltage feedback value and reference feedback value, thereby changing the output voltage parameter to compensate for component variability and achieve consistent current flow across different components.
3Use of energy by moving object
If a voltage regulator with feedback control is used, then power efficiency is improved, but device complexity increases due to additional control components
Solution Approach 1:
The control element (microcontroller) serves multiple functions: it converts the voltage feedback value to a digital value via ADC, compares it with the reference feedback value, determines the control value for the DAC, and outputs the control signal. By consolidating these multiple functions into a single multi-functional control element, the patent reduces overall circuit complexity while maintaining the power efficiency benefits of feedback control.
Solution Approach 2:
The patent combines the ADC, control element, and DAC into an integrated control system. The control element integrates the comparison logic and control decision-making, while the ADC and DAC are positioned as interface components between the analog feedback/voltage paths and the digital control logic. This merging of functions into a unified control architecture reduces the number of separate components and simplifies the overall device structure.
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 approach enhances efficiency by up to 30% compared to uncontrolled systems, optimizing power use and extending battery life in portable devices, while accommodating varying forward voltages and LED types, and allowing for dynamic control and brightness adjustments.
Implementation Method 1
A voltage divider is connected between the first terminal and the reference potential terminal and comprises a divider node for tapping a divided voltage
Implementation Method 2
A comparator has a first input for receiving a reference voltage, a second input connected to the divider node, and an output connected to the control input
Implementation Method 3
an analog-to-digital converter, AD converter, for generating a digital voltage feedback value from a voltage applied to the second terminal
Implementation Method 4
a digital-to-analog converter, DA converter, coupled to the divider node, for outputting an analog control signal based on a digital control value
Implementation Method 5
the second terminal is coupled to a reference potential terminal via a series resistor
Data Source
AI summary
A supply circuit for supplying a light-emitting element includes a voltage regulator having a voltage output for outputting an output voltage and having a control input for regulating the output voltage based on a voltage at a divider node of a voltage divider. A first and a second terminal are used to connect the light emitting element, the first terminal being coupled to the voltage output and the second terminal being coupled to a reference potential terminal via a series resistor. The supply circuit further includes a control block having an analog-to-digital converter for generating a digital voltage feedback value from a voltage applied to the second terminal, a control element, and a digital-to-analog converter coupled to the divider node for outputting an analog control signal based on a digital control value. The control element is arranged to compare the voltage feedback value with a reference feedback value, if the voltage feedback value is less than the reference feedback value, to change the control value in a first direction, and if the voltage feedback value is greater than the reference feedback value, to change the control value in a second direction.