Adaptive Overvoltage Protection for LED Chains
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Solution Overview
Problem
LED chains in applications like automotive lighting face damage due to excessive energy dissipation when an open-load condition occurs, as the stored energy in the output capacitor can be discharged across active LEDs, potentially causing damage, especially when the number of active LEDs is low.
Innovation Solution
A driver circuit is configured to adjust the voltage level of the power signal based on the number of active LEDs, scaling the voltage feedback value or overvoltage threshold to limit the energy discharged, thereby reducing the risk of damage by controlling the ratio of active LEDs to the overvoltage threshold, which involves scaling the voltage feedback value or threshold based on the number of active LEDs in the chain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of active LEDs is reduced to provide lighting flexibility, then adaptability is improved, but the risk of overvoltage damage increases
Solution Approach 1:
The overvoltage threshold is made dynamic by scaling it according to the number of active LEDs. When fewer LEDs are active, the threshold is reduced proportionally, preventing overvoltage damage while maintaining lighting flexibility. This resolves the contradiction by making the protection mechanism adaptive to different operational configurations.
Solution Approach 2:
The patent changes the parameter of overvoltage threshold based on the number of active LEDs. By scaling the threshold parameter dynamically, the system maintains reliability across different lighting configurations without sacrificing adaptability.
2Power
If the overvoltage threshold is increased to allow higher power delivery, then power delivery capability is improved, but the risk of LED damage increases
Solution Approach 1:
The overvoltage threshold dynamically adjusts based on the number of active LEDs, allowing higher power delivery when more LEDs are active (reducing individual stress) and lower thresholds when fewer LEDs are active (preventing overvoltage damage). This resolves the contradiction between power capability and damage risk.
Solution Approach 2:
The patent scales the overvoltage threshold parameter according to the quantity of active LEDs, enabling the system to optimize power delivery while maintaining safety margins. The threshold parameter changes adaptively rather than remaining fixed.
3Device complexity
If a fixed overvoltage threshold is used to simplify control, then device complexity is reduced, but protection effectiveness deteriorates
Solution Approach 1:
The patent implements dynamic parameter scaling where the overvoltage threshold is adjusted based on the number of active LEDs. This maintains protection effectiveness across different operational states without requiring complex control logic, as the scaling follows a straightforward relationship.
Data Source
AI summary
In one example, a method includes determining, by a device of a system, a voltage feedback value that represents a voltage level of a power signal being provided to a plurality of load elements that are selectively active. In this example, the method also includes adjusting, by the device and based on a quantity of load elements of the plurality of load elements that are active, the voltage level of the power signal such that the voltage feedback value remains less than or equal to an overvoltage threshold.