Gate Off Delay Compensation Circuit for LED Driving
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Solution Overview
Problem
AC-coupled driving circuits for LED light apparatuses experience gate off delay and propagation delay, leading to increased average driving current and reduced efficiency, which results in heating phenomena and reduced integrated circuit performance.
Innovation Solution
A gate off delay compensation circuit that includes a sensing interval determiner, a driving voltage excess interval determiner, and a driving voltage period determiner, which extend the period of the driving voltage based on the sensing and excess intervals to control the driving current, using capacitors and switching elements to generate enable signals and determine the driving voltage period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an AC-coupled driving circuit is used to directly use an AC current source, then power consumption is decreased and LED substitution is enabled, but gate off delay and propagation delay occur during switching element operation, causing maximum values of driving current and voltage to increase along with input voltage
Solution Approach 1:
The patent applies preliminary action by extending the gate off period in advance based on the driving voltage excess interval. The gate off delay compensation circuit calculates the excess interval where driving voltage exceeds reference voltage and proactively extends the gate off period to compensate for the gate off delay, preventing current and voltage peaks before they occur.
Solution Approach 2:
The patent implements feedback by continuously monitoring the driving voltage and comparing it with the reference voltage to determine the driving voltage excess interval. This feedback information is used to dynamically adjust the gate off period, creating a closed-loop control system that compensates for delays in real-time.
2Device complexity
If the gate off delay is not compensated, then the circuit operation is simple, but the average driving current increases along with input voltage, reducing integrated circuit efficiency and generating heating phenomenon
Solution Approach 1:
The patent introduces an intermediary gate off delay compensation circuit between the AC current source and the LED driving circuit. This intermediary component processes the driving voltage signal, determines the excess interval, and generates compensated gate control signals, thereby isolating the main driving circuit from the complexity of delay compensation while improving overall efficiency.
3Productivity
If the driving voltage period is extended based on the driving voltage excess interval, then the average driving current is reduced and efficiency is improved, but additional circuit components are required to determine sensing interval and excess interval
Solution Approach 1:
The gate off delay compensation circuit performs multiple functions using a unified structure: it senses the driving voltage, compares it with reference voltage, determines both the sensing interval and driving voltage excess interval, calculates the compensation period, and generates the compensated gate control signal. This multi-functional approach reduces the need for separate dedicated circuits for each function.
Data Source
AI summary
A gate off delay compensation circuit includes a sensing interval determiner configured to determine an interval in which a driving voltage corresponds to a first and second level of a reference voltage as a driving voltage sensing interval, a driving voltage excess interval determiner configured to determine a driving voltage excess interval defined as an interval in which the driving voltage is larger than the reference voltage and a driving voltage period determiner configured to determine a period of the driving voltage based on the driving voltage sensing interval and the driving voltage excess interval. Therefore, a gate off delay compensation circuit 100 decreases an average driving current and an average driving voltage and allows decrease of a variation of a driving current according to a change of a input voltage VIN.