Multi-Channel LED Driver Circuit for Microcontroller-Free Wiping
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Solution Overview
Problem
Conventional LED driver circuits for wiping turn indicators require a microcontroller to generate the sequence of switching LEDs on and off, increasing overall costs and complexity.
Innovation Solution
A circuit design that utilizes a multi-channel LED driver IC with a unique connection of LEDs in series and an analog delay circuit, eliminating the need for a microcontroller by enabling automatic switching based on reference and sense voltages, and reducing power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a microcontroller is used to generate the switching sequence for LEDs, then the wiping effect can be achieved, but the overall costs and device complexity increase
Solution Approach 1:
The patent extracts the microcontroller from the system and replaces it with a simplified analog circuit implementation. The switching sequence generation function is taken out from digital control domain and implemented through analog voltage propagation and comparator circuits, eliminating the need for complex microcontroller hardware while achieving the same wiping effect automation
Solution Approach 2:
The patent substitutes the digital/microelectronic control system (microcontroller) with an analog electronic control system using operational amplifiers, capacitors, and resistors. This replacement reduces device complexity by using simpler, more cost-effective analog components that naturally provide the required timing and sequencing functions through RC time constants and voltage propagation delays
2Extent of automation
If conventional LED driver circuits are used with microcontroller control, then the wiping effect is achieved, but power dissipation increases
Solution Approach 1:
The patent implements periodic action through the analog delay circuit that sequentially activates each LED channel in a time-ordered sequence. The RC time constants create natural time delays that cause LEDs to switch on and off in sequence, achieving the wiping effect through periodic, rhythmic activation patterns rather than continuous or simultaneous operation, thereby reducing overall power dissipation
Solution Approach 2:
The patent applies preliminary action through the analog delay circuit that pre-charges capacitors and progressively builds voltage on each channel before activation. The sequential voltage propagation ensures that only one or a few LEDs are active at any given time, with subsequent channels being preliminarily prepared through voltage charging on capacitors before their turn to activate, minimizing simultaneous power consumption across all channels
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
Achieves a wiping effect without a microcontroller, reducing costs and power dissipation while maintaining the same visible output, by automatically regulating load currents through each channel.
Implementation Method 1
an analog delay circuit including a capacitor connected to the enable input of the first channel
Implementation Method 2
an analog delay circuit including a capacitor connected to the enable input of the first channel, wherein the enable input of each channel is connected to the enable input of a neighboring channel via a resistor
Implementation Method 3
The current regulation is based on a reference voltage and a sense voltage present at the sense node of the respective channel
Data Source
AI summary
A circuit for driving a plurality of LEDs includes a plurality of channels, wherein each channel has an enable input and is configured to regulate—when enabled—a load current flowing from an output node to a sense node of the respective channel. The current regulation is based on a reference voltage and a sense voltage present at the sense node of the respective channel. The circuit further includes a main sense resistor connected to the sense node of a first channel of the channels and one or more additional sense resistors, wherein the sense node of each channel is connected to a sense node of a neighboring channel via one of the additional sense resistors. A chain of LEDs is coupled to the circuit, and the output node of each channel is connected to an output node of a neighboring channel via at least one LED of the chain of LEDs and wherein an input node is connected to the output node of a last channel of the channels via at least one LED of the chain of LEDs. Moreover, the circuit includes an analog delay circuit including a capacitor connected to the enable input of the first channel, wherein the enable input of each channel is connected to the enable input of a neighboring channel via a resistor and wherein the enable input of the last channel is coupled to a voltage source configured to provide a voltage based on the voltage present at the input node.