PWM LED Driver Circuit with Feedback Voltage Detection
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Solution Overview
Problem
Conventional LED driver circuits lack an efficient method to prevent overvoltage damage to LED arrays without requiring separate overvoltage protection devices, necessitating frequent adjustments in resistor values as LED configurations change, which increases development and testing costs.
Innovation Solution
A Pulse Width Modulation (PWM) controlling circuit and LED driver circuit that detects the connection status of LED arrays through feedback voltage levels, generates a control signal to manage boosting, and uses a feedback unit to adjust the driving voltage, eliminating the need for external overvoltage protection devices by determining the minimum feedback voltage for connected arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional overvoltage protection technique uses a resistor array to detect voltage levels, then overvoltage protection is achieved, but the resistance value must be separately adjusted every time the LED inch is changed, increasing development and test process costs
Solution Approach 1:
The system uses the LED arrays themselves to provide the feedback signal for overvoltage protection. The feedback voltage is derived from the LED arrays' own operating characteristics, eliminating the need for separate resistor arrays that would require manual adjustment. The LED arrays self-indicate their connection status and voltage levels through their inherent electrical properties.
Solution Approach 2:
The patent implements a feedback mechanism where the voltage levels from the LED arrays are continuously monitored and fed back to the controller. This feedback loop allows the system to automatically detect connection status and adjust boosting operations without requiring manual resistor adjustment, thereby reducing development and test costs while maintaining overvoltage protection.
2Stability of the object's composition
If the driver circuit performs continuous boosting operation to maintain uniform brightness, then brightness uniformity is improved, but without overvoltage protection devices, the boosting destroys the LED IC
Solution Approach 1:
The system continuously monitors the voltage levels from the LED arrays and uses this feedback to control the boosting operation. The controller adjusts the boosting based on the actual voltage levels detected, preventing overvoltage conditions while maintaining brightness uniformity. This feedback-based control eliminates the need for separate overvoltage protection devices.
Solution Approach 2:
The boosting operation is made dynamic rather than static. The driver circuit continuously adjusts the boosting level based on real-time voltage feedback from the LED arrays. This dynamic adjustment allows the system to maintain optimal brightness uniformity while preventing overvoltage damage, adapting to changing conditions without requiring fixed protection circuits.
3Reliability
If separate overvoltage protection devices are added to prevent overvoltage damage, then LED IC protection is improved, but device complexity and cost increase
Solution Approach 1:
The LED arrays serve multiple functions: they act as both the light-emitting load and the sensing element for overvoltage detection. The same components that perform the primary function also provide the feedback signal for protection, eliminating the need for separate dedicated protection devices and reducing overall circuit complexity.
Solution Approach 2:
The system uses the LED arrays' own electrical characteristics to provide protection functionality. The voltage levels generated by the LED arrays during normal operation are directly utilized as feedback signals for overvoltage detection and control, making the protection mechanism self-contained and eliminating the need for additional external protection devices.
Data Source
AI summary
A Light Emitting Diode (LED) driver circuit and a Pulse Width Modulation (PWM) controlling circuit thereof is provided. The LED driver circuit includes a voltage detector connected to a plurality of LED arrays, the voltage detector being configured to determine a connection status of each of the LED arrays according to a level of a feedback voltage of each of the LED arrays, and detect a minimum feedback voltage from the feedback voltage of each of the LED arrays that are determined to be connected, a controller configured to output a control signal to control boosting of the LED arrays according to the detected minimum feedback voltage, a PWM signal generator configured to output a PWM signal corresponding to the outputted control signal, and a driving voltage generator configured to supply a driving voltage commonly to the LED arrays according to the PWM signal.