Transistor Control Circuit for LED Driving Efficiency
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Solution Overview
Problem
Linear LED driving circuits suffer from inefficiency and voltage disturbances, leading to power consumption issues and LED flickering during grid voltage fluctuations.
Innovation Solution
A control circuit with a reference signal generating circuit and a driver stage circuit that outputs a reference signal with opposing trends in different time periods within a cycle, based on current sampling signals, to stabilize current flow through the transistor and mitigate voltage disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a linear LED driving circuit is used, then the structure is simple and cost is low, but the efficiency is poor and power consumption is high
Solution Approach 1:
The patent applies dynamic control by using a transistor with pulse-width modulation (PWM) to dynamically adjust the current flowing through the LED based on the reference signal. This allows the circuit to operate in switching mode rather than linear mode, significantly improving efficiency while maintaining reasonable complexity through dynamic operation.
Solution Approach 2:
The patent implements periodic action through the oscillating reference signal that periodically switches the transistor on and off. This periodic switching enables pulse-width modulation control, where the duty cycle of the pulses regulates the average current to the LED, achieving efficient power control with reduced energy loss.
2Device complexity
If a linear LED driving circuit is used, then the structure is simple, but voltage disturbances cause LED flickering
Solution Approach 1:
The patent implements feedback control by comparing the actual current through the LED ( sensed via sampling resistor) with the reference signal, and adjusting the transistor gate voltage accordingly. This feedback mechanism compensates for voltage disturbances and maintains stable LED operation, eliminating flickering caused by grid voltage fluctuations.
Solution Approach 2:
The dynamic PWM control allows the circuit to rapidly respond to voltage disturbances by adjusting the switching duty cycle in real-time. This dynamic response capability enables the system to maintain stable LED current despite external voltage variations, improving reliability without requiring complex filtering circuits.
Data Source
AI summary
A control circuit for controlling a transistor includes a reference signal generating circuit and a driver stage circuit. The reference signal generating circuit outputs a reference signal, and to control the reference signal having a first change trend in a first time period of a time interval and having a second change trend in a second time period of the time interval based on time. The driver stage circuit is configured to control the transistor according to the reference signal and a current sampling signal, so that the current flowing through the transistor changes with the reference signal.