LED Driver Current Controller Switch Off Time Calculation
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Solution Overview
Problem
Existing LED driver systems face challenges in reducing component count, form factor, and require improved switching control to manage voltage and current fluctuations, particularly in continuous conduction mode, while avoiding secondary voltage feedback that burdens transformer or inductive elements.
Innovation Solution
A current controller system that calculates the switch-off time of an electronic switch, such as a MOSFET, at each clock cycle to regulate current based on feedback voltage comparisons, allowing for continuous-conduction-mode operation, using mathematical expressions to determine regulated current and voltage across the LED load, and avoiding secondary voltage feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secondary voltage feedback control is used, then voltage regulation is achieved, but transformer or inductive elements are burdened
Solution Approach 1:
The patent extracts the feedback sensing function from the secondary side to the primary side by measuring the voltage across the electronic switch. This eliminates the need for secondary voltage feedback through the transformer, thereby reducing the burden on transformer or inductive elements while maintaining voltage regulation capability.
2Quantity of substance
If component count is reduced, then form factor is minimized, but switching control capability may be compromised
Solution Approach 1:
The patent combines multiple functions into the current controller: it performs current regulation, switch timing control, and voltage sensing all through a single integrated controller on the primary side. This merging of functions reduces component count while maintaining comprehensive switching control capability.
Solution Approach 2:
The current controller is designed as a multi-functional device that can regulate current, control switch timing, sense voltage, and protect against over-voltage and short circuits. This universal controller eliminates the need for separate components for each function, reducing overall component count while enhancing control capability.
3Stability of the object's composition
If switch-off time is precisely controlled, then continuous conduction mode is achieved, but control complexity increases
Solution Approach 1:
The patent implements feedback control by measuring the voltage across the electronic switch and using this feedback signal to adjust the switch-off time. The controller compares the measured voltage with reference levels and dynamically adjusts the timing to maintain continuous conduction mode, achieving stability through closed-loop feedback rather than complex open-loop control.
Data Source
AI summary
A device for providing regulated current to an electrical load comprising a current controller operable at predetermined intervals (clock cycles) to receive:—i. a desired input reference voltage; and ii. a feedback voltage obtained from an electronic switch; wherein the current controller is operable to compare the feedback voltage with the desired input reference voltage and provide regulated current to the electrical load based on calculation of the switch off time of the electronic switch at each clock cycle; the calculation of the switch off time operable to achieve a continuous-conduction-mode (CCM) for the device under normal operating conditions, is disclosed.