LED Driver Gate Driver Voltage Source Switching
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Solution Overview
Problem
LED drivers face challenges in operating effectively at low input voltages, as they often fail to provide adequate voltage for LED current regulation, leading to inefficiencies and potential damage due to the need for additional components like charge-pumps and large capacitors, which increase cost and size.
Innovation Solution
The implementation of a boost converter with a controllable switch and a gate driver powered by a linear regulator that switches between input and secondary voltage sources, utilizing a voltage comparator with hysteresis to ensure stable operation even at low input voltages, allowing the LED driver to boost the input voltage and maintain proper switching control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a charge-pump is used to provide sufficient voltage for LED current regulation, then the LED driver can operate at low input voltages, but additional external components are required and another switching frequency is introduced which may be an EMI hazard
Solution Approach 1:
The patent combines the charge-pump voltage boosting function with the existing LED driver circuitry by using the same inductor and switching node. The gate driver is integrated to control the main power switch, eliminating the need for separate charge-pump components while achieving the same voltage boosting effect for low-input-voltage operation.
Solution Approach 2:
The main power switch and inductor in the LED driver are made to serve dual functions: both LED current regulation and voltage boosting for low-input-voltage operation. The gate driver circuit is designed to provide both switch control and voltage boosting, reducing overall component count and complexity.
2Stability of the object's composition
If large capacitors are used to buffer the supply voltage during temporary low-voltage events, then voltage stability is improved, but physical size and cost increase
Solution Approach 1:
The gate driver is designed to detect low-voltage conditions and switch to alternative power sources before the voltage drops to critical levels. This preliminary action prevents voltage instability without requiring large buffering capacitors, as the system proactively manages power sources based on voltage conditions.
Solution Approach 2:
The patent introduces a voltage detector and multi-source power selection circuit as intermediaries between the input voltage and the LED driver circuit. These intermediaries monitor voltage levels and switch between different power sources (input voltage, boosted voltage, or external power source) to maintain stability without requiring large capacitors.
3Device complexity
If the gate driver is powered directly from input voltage, then circuit simplicity is maintained, but adequate voltage for switching control cannot be ensured at low input voltages
Solution Approach 1:
The gate driver power supply is designed to dynamically switch between multiple voltage sources based on input voltage conditions. When input voltage is sufficient, the gate driver is powered directly from the input. When input voltage drops below the threshold, the system automatically switches to an alternative power source (boosted voltage or external power source), ensuring adequate switching control voltage while maintaining circuit simplicity through automated source selection.
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
This solution enables LED drivers to operate reliably at low input voltages, preventing damage and ensuring stable LED function, while reducing the need for additional components and minimizing size and cost, with the hysteresis function enhancing noise resistance and stability.
Implementation Method 1
a boost converter to boost an input voltage to a desired voltage to power one or more LED strings
Implementation Method 2
a gate driver powered by a linear regulator, which switches between different voltage sources to ensure that the gate driver is able to provide enough voltage for switching
Implementation Method 3
The comparator may incorporate a hysteresis function such that when the input voltage returns above a sum of the threshold and an offset, the comparator will output a signal to cause the linear regulator to re-connect to the input voltage as power source
Data Source
AI summary
An LED driver with ability to operate at low input voltages is disclosed. The LED driver comprises a boost converter to boost an input voltage to a desired output voltage to power one or more LED strings. The boost converter incorporates a first controllable switch, such as a metal-oxide-semiconductor field-effect transistor (MOSFET), IGBT, etc., for output voltage control. The boost converter receives input from an external source, such as a battery voltage, as power source for voltage boost operation. The first controllable switch couples to a gate driver powered by a linear regulator, which switchably couples to different voltage sources via a second switch to ensure that the gate driver is able to provide enough voltage for switching the first controllable switch.