Cascaded LED Driver Dynamic Voltage Control
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Solution Overview
Problem
Conventional LED drivers face inefficiencies due to variations in bias voltages across LED strings caused by process variations and temperature changes, leading to excessive power consumption as they use fixed, higher output voltages to ensure proper operation.
Innovation Solution
A cascaded LED driver system that dynamically adjusts the output voltage based on the minimum tail voltage of each LED string, using a feedback mechanism to maintain optimal voltage levels across all strings, thereby reducing power consumption.
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 reliability is improved, but power consumption increases
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed output voltage to a dynamically adjustable output voltage. The LED driver continuously monitors the actual voltage requirements of LED strings and adjusts the output voltage accordingly, allowing the system to adapt to varying operating conditions and minimize power consumption while maintaining reliable operation.
Solution Approach 2:
The patent implements feedback by having the LED driver monitor the actual voltage across LED strings and use this information to adjust the output voltage. This closed-loop control ensures that the output voltage is optimized based on real-time conditions, preventing both over-voltage waste and under-voltage operation, thus resolving the contradiction between reliability and power consumption.
2Manufacturing precision
If variations in forward-voltage drops are compensated by using a higher fixed voltage, then manufacturing precision is improved, but energy efficiency deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the output voltage parameter based on the actual forward-voltage drops of LED strings. Instead of using a fixed high voltage to compensate for variations, the system measures the actual voltage requirements and adjusts the output voltage to match the minimum necessary, thereby maintaining manufacturing precision while eliminating energy waste from excessive voltage.
3Device complexity
If a serial cascade configuration is used to determine minimum tail voltages, then device complexity is reduced, but measurement precision requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the LED string array into multiple groups, each handled by a separate LED driver. This modular approach simplifies the overall system architecture by allowing independent control and measurement of each segment's voltage requirements, making the measurement task more manageable while maintaining comprehensive monitoring.
Data Source
AI summary
A light emitting diode (LED) system implements a power management technique. The LED system includes a plurality of LED drivers connected in series, each LED driver configured to regulate the current flowing through a corresponding subset of a plurality of LED strings. Each LED driver determines the tail voltages of the one or more LED strings of the corresponding subset. Each LED driver, except for the first LED driver in the series, also receives a voltage representative of the minimum tail voltage of the other subsets regulated by the upstream LED drivers. Each LED driver then provides the lowest of the voltage received from the upstream LED driver and the one or more tail voltages of the corresponding subset to the downstream LED driver. In this manner a voltage representative of the minimum tail voltage of the plurality of LED strings is cascaded through the series. A feedback controller monitors the minimum tail voltage represented by this cascaded voltage and accordingly adjusts an output voltage provided to the head ends of the plurality of LED strings.