LED Driver Dynamic Power Management Tail Voltage
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Solution Overview
Problem
Conventional LED drivers consume excessive power due to the need for a fixed voltage higher than the worst-case bias drop across LED strings, caused by variations in static and dynamic forward-voltage drops, leading to inefficient power management in LCD backlighting applications.
Innovation Solution
An LED driver system with dynamic power management that monitors the tail voltages of LED strings and adjusts the output voltage to maintain the minimum tail voltage near a predetermined threshold, using a feedback controller and boost converter to optimize power consumption while ensuring proper operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed voltage sufficiently higher than the worst-case bias drop is used to ensure proper operation of each LED string, then reliability is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic voltage adjustment by continuously monitoring the actual bias voltage required by the LED string and adjusting the output voltage accordingly. Instead of using a fixed worst-case voltage, the system adapts the voltage in real-time based on actual conditions, resolving the contradiction between ensuring proper operation and minimizing power consumption.
Solution Approach 2:
The patent employs a feedback mechanism where the actual bias voltage of the LED string is monitored and used to adjust the output voltage of the LED driver. This closed-loop control ensures that the voltage is always sufficient for proper operation while eliminating the need to over-provision with excessive fixed voltage, thereby reducing power consumption.
2Manufacturing precision
If process variations in fabrication and manufacturing of LEDs are accounted for by increasing output voltage, then manufacturing precision is improved, but loss of energy increases
Solution Approach 1:
The patent enables the LED driver system to self-adjust based on the actual characteristics of the connected LED string. By monitoring the real-time bias voltage requirements, the system automatically compensates for manufacturing variations without requiring manual calibration or over-provisioning, thus eliminating energy waste while maintaining compatibility with LEDs of varying precision.
Data Source
AI summary
Power management in a light emitting diode (LED) system having a plurality of LED strings is disclosed. A voltage source provides an output voltage to drive the LED strings. An LED driver monitors the tail voltages of the active LED strings to identify the minimum, or lowest, tail voltage and adjusts the output voltage of the voltage source based on the lowest tail voltage. The LED driver can adjust the output voltage so as to maintain the lowest tail voltage at or near a predetermined threshold voltage so as to ensure that the output voltage is sufficient to properly drive each active LED string with a regulated current in view of pulse width modulation (PWM) performance requirements without excessive power consumption.