Boost Regulator Transient Suppression for LED Drivers
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Solution Overview
Problem
Existing LED drivers face challenges in providing sufficient headroom for LED strings and experience excessive transients due to changes in load currents, particularly when different PWM dimming signals are used across channels, leading to inefficient voltage regulation and reduced brightness.
Innovation Solution
The implementation of dynamic headroom control within the LED driver circuit, which uses a boost/buck switching regulator to regulate voltage across multiple LED strings, employs a digital-to-analog converter and counter/stepping algorithm to maintain a stable voltage window and suppress transients by adding an offset to the compensation voltage during load current changes, ensuring adequate headroom and efficient current delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a boost regulator is used to regulate voltage across multiple LED strings, then voltage regulation capability is improved, but transient spikes occur during load current changes
Solution Approach 1:
The patent applies preliminary action by detecting load current changes and proactively adjusting the compensation voltage before transient spikes can occur. The system monitors the load current and modifies the compensation voltage in anticipation of transients, thereby suppressing them before they affect the output voltage stability.
Solution Approach 2:
The patent implements feedback by continuously monitoring load current changes and using this information to dynamically adjust the compensation voltage. The feedback mechanism ensures that the compensation voltage is modified in response to actual load conditions, thereby maintaining voltage regulation stability and suppressing transients.
2Stability of the object's composition
If dynamic headroom control is implemented to maintain stable voltage window, then brightness consistency is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by dynamically modifying the compensation voltage parameter in response to load current changes. This parameter adjustment enables the system to maintain a stable voltage window and ensure consistent brightness across LED strings without requiring complex additional hardware.
3Object-affected harmful factors
If compensation voltage is adjusted during load current changes, then transient suppression is improved, but power dissipation increases
Solution Approach 1:
The patent applies partial action by adjusting the compensation voltage only to the extent necessary to suppress transients, rather than making excessive adjustments. This controlled approach ensures transient suppression while minimizing unnecessary power dissipation from over-adjustment of the compensation voltage.
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 ensures stable and efficient voltage regulation across LED strings, reducing transient spikes and maintaining peak current delivery, even during short pulses, thereby enhancing brightness consistency and reducing power dissipation.
Implementation Method 1
The drive voltage for the LED strings is regulated from an input voltage node by switching the current in an inductor
Implementation Method 2
The other side of the inductor is connected to an anode of a diode
Data Source
AI summary
A circuit for generating an output voltage to a top node of a plurality of LED strings. The circuit includes an inductor having a load current flowing therethrough and a switching transistor responsive to a switching control signal. An integrator generates a compensation voltage responsive to a voltage at a bottom node of the LED string and a reference voltage. Circuitry for combining ana correction offset with the compensation voltage is responsive to the compensation voltage and the load current through the inductor. The offset is generated only during a step load change of the load current and substantially reduces voltage transients from the compensation voltage and the output voltage. A summation circuit sums the compensation voltage including the correction offset with at least the voltage at the bottom node of the LED string to generate a first control signal. A latch generates the switching control signal responsive to the first control signal and a leading edge blanking signal.