Backlight LED Driver Circuit Current Regulation
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Solution Overview
Problem
Traditional backlight LED driver circuits face challenges in precise current control and noise immunity, especially at low currents, and are prone to overheating due to high pin voltages at high currents.
Innovation Solution
A backlight LED driver circuit with a current regulating function, incorporating a current regulator module with multiple current channels and a voltage regulator module, including transistors and a decoder, to control the LED current and voltage accurately, using a current mirror configuration and a constant current source to regulate the LED string's current and voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional amplifier and transistor configuration is used for LED current control, then the circuit can operate with simple structure, but current accuracy deteriorates at low currents due to amplifier bias voltage and common-mode noise
Solution Approach 1:
The current regulation function is divided into multiple independent current channels, each capable of precise current control. This segmentation allows the circuit to achieve accurate low-current operation by isolating the control of each channel, avoiding the bias voltage and noise issues of a single amplifier-based system.
Solution Approach 2:
The patent replaces the traditional amplifier-based voltage control mechanism with a transistor-based direct current control mechanism. By using transistors to directly regulate current through current channels, the system eliminates the need for high-precision voltage amplification, thereby avoiding amplifier bias voltage and common-mode noise issues.
2Illumination intensity
If high current is applied to increase LED brightness, then illumination intensity improves, but temperature increases due to high pin voltage causing overheating
Solution Approach 1:
The patent implements a feedback mechanism where the voltage at the LED's low-voltage terminal is continuously monitored and fed back to the control circuit. This feedback allows the system to dynamically adjust the current channels to maintain the pin voltage within a safe range, preventing overheating while enabling high current operation for increased brightness.
Solution Approach 2:
The system dynamically changes the operating parameters of the current channels based on real-time feedback. By adjusting the current distribution across multiple channels and modifying the voltage regulation parameters, the circuit can maintain low pin voltage even at high LED currents, preventing thermal runaway and overheating.
3Measurement precision
If multiple current channels are introduced to improve current control accuracy, then current regulation precision improves, but device complexity increases
Solution Approach 1:
Multiple current channels are merged into a unified control architecture where all channels share common control logic and voltage regulation mechanisms. This merging approach allows the system to achieve high current regulation accuracy through parallel current paths while avoiding the exponential complexity increase that would result from completely independent control circuits for each channel.
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 ensures precise control and noise immunity across a wide range of currents, preventing overheating by maintaining a low voltage at the LED's low-voltage terminal, thus improving linearity and accuracy of current regulation.
Implementation Method 1
the fourth transistor, the fifth transistor, and the sixth transistor in the voltage regulator module and the second transistor and one third transistor of each of the current channels in the current regulator module constitute a current mirror
Implementation Method 2
a constant current source configured to supply a reference current Iref
Implementation Method 3
a LED light-emitting element
Data Source
AI summary
A backlight LED driver circuit with current regulating function is provided. The backlight LED driver circuit includes: a LED light-emitting element, a first transistor, a first amplifier, a current regulator module, and a voltage regulator module; the current regulator module including a plurality of current channels, each including one second transistor and one third transistor; the voltage regulator module including a fourth transistor, a fifth transistor, and a sixth transistor; the fourth transistor, the fifth transistor, and the sixth transistor in the voltage regulator module and the second transistor and one third transistor of each of the current channels in the current regulator module constitute a current mirror; and the current regulator module further including a decoder configured to generate a signal for controlling on and off states of the plurality of second transistors in the plurality of current channels in response to an input digital control signal.