Phase Shift Controller for LED Dimming Using Shared Counters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light emitting diode (LED) driving circuits face challenges in phase shift burst dimming operations, requiring external processors for signal generation and increasing design complexity and costs, especially when adjusting the number of LED channels.
Innovation Solution
A phase shift controller that receives a pulse-width modulated dimming signal to generate burst control signals for multiple LED channels with differing phases, eliminating the need for external processors and reducing circuit complexity by using only two counters, allowing for automatic generation of burst control signals from a single dimming pulse signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase shift burst dimming control is implemented using external processors to generate burst control signals, then the phase shift operation can be achieved, but the device complexity and design burden increase significantly
Solution Approach 1:
The patent merges the burst control signal generation function into the existing PWM control circuit by adding counters that generate phase-shifted control signals for multiple LED strings simultaneously. This integration eliminates the need for external processors and reduces device complexity while maintaining reliable phase shift burst dimming operation.
Solution Approach 2:
The PWM control circuit is enhanced to perform multiple functions: it generates PWM signals for dimming control and simultaneously generates phase-shifted burst control signals for multiple LED channels using shared counters. This multi-functionality reduces the need for separate external processing units and simplifies the overall system architecture.
2Ease of operation
If external processors are used to generate burst control signals for each LED channel, then phase shift control is achieved, but design costs and customization requirements increase
Solution Approach 1:
The patent combines burst control signal generation for multiple channels into a single integrated circuit module that uses shared counters and PWM control logic. This merging approach eliminates the need for multiple external processors and reduces design costs while maintaining ease of operation for phase shift control.
Solution Approach 2:
The circuit uses configurable counters with adjustable parameters (such as counter initial values and clock division ratios) that can be dynamically set to achieve different phase shift patterns for different numbers of LED channels. This dynamic configurability provides ease of operation without requiring costly custom design for each application.
3Adaptability or versatility
If separate counters are provided for each LED channel to generate burst control signals, then channel-specific control is achieved, but circuit area increases
Solution Approach 1:
The patent merges the counting function into a single shared counter that serves all LED channels simultaneously. The counter generates phase-shifted control signals by distributing its output to multiple channels with different timing relationships. This approach maintains channel control flexibility while significantly reducing circuit area compared to using separate counters for each channel.
Solution Approach 2:
The patent segments the burst control signal generation into time-multiplexed phases, where a single counter sequentially generates control signals for different channels at different time intervals. This temporal segmentation allows one counter to perform the work of multiple counters, reducing circuit area while maintaining adaptability for different channel configurations.
Data Source
AI summary
A positive counter starts counting, starting with an initial value, upon receiving a positive edge of a dimming pulse signal. A negative edge counter starts counting, starting with an initial value, upon receiving a negative edge of the dimming pulse signal. For each i-th (2≦i≦n) channel, the phase shift amount is calculated by multiplying a period count value that indicates the period of the dimming pulse signal by (i−1)/n. When the count value matches the phase shift amount, a burst control signal is switched to a first level. When the count value matches the phase shift amount, the burst control signal is switched to a second level.