LED Driver Feedback Calibration for Dynamic Voltage Adjustment
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Solution Overview
Problem
Conventional LED drivers consume excessive power due to the use of fixed, high output voltages to account for variations in bias voltages across LED strings, which are caused by process variations and temperature changes, leading to inefficient power management in LCDs and other displays.
Innovation Solution
The implementation of a dynamic power management system with a feedback mechanism that adjusts the output voltage based on the minimum tail voltage of LED strings, using a feedback loop calibrated to optimize power consumption while ensuring proper operation, employing a feedback controller with a loop calibration module to determine a feedback compensation factor and adjust the output voltage dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed high output voltage is used to ensure proper operation of all LED strings, then the reliability of LED operation is improved, but the power consumption increases unnecessarily
Solution Approach 1:
The LED driver transitions from a fixed output voltage mode to a dynamic output voltage mode. The output voltage is continuously adjusted based on feedback from LED string tail voltages, allowing the system to adapt to varying LED characteristics and operating conditions. This dynamic adjustment ensures sufficient voltage for reliable operation while minimizing excess voltage that would waste power.
Solution Approach 2:
The patent implements a feedback mechanism where the output voltage is monitored through tail voltage measurements of LED strings. The feedback controller uses this information to adjust the output voltage accordingly, creating a closed-loop system that automatically optimizes power consumption while maintaining reliable LED operation. The feedback loop continuously adapts to process variations and temperature changes.
2Adaptability or versatility
If a fixed high output voltage is used to account for variations in bias voltages, then the adaptability to LED variations is improved, but the power consumption increases
Solution Approach 1:
The system replaces fixed voltage output with dynamic voltage adjustment. The output voltage continuously adapts to match the actual requirements of LED strings, accounting for process variations in fabrication and temperature changes. This dynamic adaptation eliminates the need for excessive headroom voltage while maintaining sufficient voltage for all LED strings under varying conditions.
Solution Approach 2:
The patent changes the operating parameter from fixed output voltage to variable output voltage. By adjusting the output voltage parameter in response to feedback from tail voltage measurements, the system adapts to different LED string characteristics without wasting power on excessive voltage headroom. This parameter adjustment allows the system to be both adaptable and power-efficient.
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 a plurality of LED strings. An LED driver implements a feedback mechanism to monitor the tail voltages of the active LED strings to identify the minimum tail voltage and adjust the output voltage of the voltage source based on the lowest tail voltage. A loop calibration module of the LED driver calibrates the feedback mechanism of the LED driver based on a relationship between a digital code value used to generate a particular output voltage and another digital code value generated based on the minimum tail voltage resulting from the particular output voltage.