LED Driver MOSFET Biasing for TRIAC Holding Current
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Solution Overview
Problem
LED lighting devices experience flickering and shimmering in deep dimming situations due to insufficient holding current, causing premature turn-off of TRIAC type dimmers, which affects user experience.
Innovation Solution
A control method and circuit configuration that biases a switch, such as a MOSFET, to consume additional power and sustain the holding current, using a control circuit to dynamically adjust operation modes and generate control signals to maintain energy transfer to the load, ensuring proper operation of TRIAC type dimmers in deep dimming conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the LED driver operates in deep dimming mode to reduce power consumption, then energy efficiency is improved, but the holding current becomes insufficient causing TRIAC dimmer premature turn-off
Solution Approach 1:
The patent segments the power consumption into two distinct components: first energy for LED load operation and second energy for sustaining holding current. The control circuit separately manages these energy components by detecting dimming characteristics and selectively biasing the switch to consume the second energy, thereby maintaining reliable TRIAC dimmer operation while minimizing overall power consumption.
Solution Approach 2:
The patent dynamically changes the operational parameters of the switch based on detected dimming characteristics. By adjusting the biasing state of the switch between different operating modes (off mode, linear mode, saturation mode), the system adapts the holding current level to match the dimming requirements, ensuring reliable dimmer operation across varying power consumption levels.
2Reliability
If additional power is consumed to sustain holding current, then TRIAC dimmer operation reliability is improved, but overall energy efficiency deteriorates
Solution Approach 1:
The patent applies partial action by consuming only the minimum necessary second energy required to sustain holding current, rather than continuously consuming maximum power. The control circuit selectively activates the switch biasing only when dimming characteristics indicate the need for holding current, thereby maintaining TRIAC dimmer reliability while minimizing energy consumption.
Solution Approach 2:
The system dynamically adjusts the switch biasing state based on real-time detection of dimming characteristics. The control circuit transitions the switch between different operational modes (off, linear, saturation) depending on the required holding current level, optimizing the balance between TRIAC dimmer operation reliability and energy efficiency under varying operating conditions.
3Ease of operation
If the switch is biased to consume second energy for holding current, then device complexity increases, but deep dimming performance is improved
Solution Approach 1:
The control circuit is designed with multi-functionality to perform both LED load control and TRIAC dimmer holding current management using the same switch and control infrastructure. By detecting dimming characteristics and selectively biasing the switch for different energy components, the control circuit handles multiple functions without requiring separate dedicated circuits, thereby improving deep dimming performance while limiting complexity increase.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively sustains the holding current during deep dimming situations, preventing premature turn-off of TRIAC type dimmers and ensuring stable operation of LED lighting devices, thereby improving user experience by maintaining consistent lighting.
Implementation Method 1
biasing the MOSFET in a linear mode to turn on the MOSFET to store the first energy in a magnetic component in connection with the MOSFET
Implementation Method 2
biasing the MOSFET in an off mode to turn off the MOSFET to transfer the first energy from the magnetic component to the load
Data Source
AI summary
Aspects of the disclosure provide a method for driving dimmable load. The method includes detecting a dimming characteristic in an energy source from which a load draws a first energy according to the dimming characteristic. The dimming characteristic requires a second energy in addition to the first energy to be drawn from the energy source to sustain an operation of the energy source. The method further includes biasing a switch to consume the second energy. The second energy and the first energy are drawn from the energy source to sustain the operation of the energy source.