LED Driver Dynamic Voltage Adjustment for Power Efficiency
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Solution Overview
Problem
Conventional LED drivers consume excessive power due to the use of fixed voltage outputs that exceed the necessary headroom for current regulation, leading to inefficiencies in LED string operation, especially with variations in bias voltages caused by temperature changes and manufacturing variations.
Innovation Solution
A feedback controller dynamically adjusts the output voltage of the LED driver to maintain the minimum tail voltage of LED strings at or near a predetermined threshold, reducing unnecessary power consumption by selectively enabling and disabling components during sampling periods and synchronizing PWM control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed voltage sufficiently higher than worst-case bias drop is provided to ensure sufficient voltage headroom, then current regulation reliability is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic voltage adjustment where the LED driver transitions from a fixed voltage output to a dynamically adjustable voltage output. The feedback controller continuously monitors tail voltages and adjusts the output voltage in real-time to maintain minimum headroom requirements, thereby reducing unnecessary power consumption while ensuring current regulation reliability is maintained under varying operating conditions
Solution Approach 2:
The patent employs a feedback controller that monitors the tail voltages of LED strings and uses this information to dynamically adjust the output voltage. This closed-loop feedback mechanism ensures that the voltage is increased only when necessary to maintain sufficient headroom for current regulation, preventing excessive power consumption while guaranteeing reliability
2Speed
If components are continuously enabled to maintain ready state, then response time is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic sampling of tail voltages at specific points during LED operation rather than continuous monitoring. The feedback controller is enabled during sampling periods to measure tail voltages and adjust output voltage, then disabled between samples to reduce power consumption. This periodic action maintains system responsiveness while significantly reducing average power consumption of the control circuitry
Data Source
AI summary
A light emitting diode (LED) system implements a LED driver to drive a set of one or more LED strings. The LED driver includes a voltage source to provide an adjustable output voltage to a head end of each LED string of the set for a first duration and a second duration following the first duration. The LED driver further includes a feedback controller to control the voltage source to adjust the output voltage for the second duration based on a digital code value generated from a minimum tail voltage of one or more tail voltages of the set at a sample point of the first duration. The LED driver further includes a power controller to temporarily enable one or more components of the feedback controller for a sample period of the first duration, the sample period comprising the sample point.