Load Driving Device PWM Signal Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional load driving devices that use a single external control signal for both on/off control and PWM driving of loads suffer from degradation in linearity and dynamic range, particularly due to time delays in starting up reference voltage and current supplies, which deviate the drive current from ideal on-duty ratios, especially at higher PWM frequencies.
Innovation Solution
A load driving device is designed with an enabling control section that generates an enabling signal from an externally inputted PWM signal, allowing the load driving section to be turned on/off and PWM-driven independently, using a separate signal path for the enabling signal and brightness control signal, thereby maintaining the LED driver IC in an on state during brightness control without repeated on/off cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single external control signal is used for both on/off control and PWM driving, then the number of pins is reduced, but time delay occurs during start-up of reference voltage and current supplies
Solution Approach 1:
The patent segments the control signal processing by creating separate signal paths: one for on/off control (enabling signal EN) and another for PWM brightness control (PWM signal). This allows the reference voltage and current supplies to be activated independently of the brightness control, eliminating the start-up delay that would otherwise occur when using a single combined control signal.
Solution Approach 2:
The enabling signal EN is generated in advance and used to activate the reference voltage supply and current supply circuits before the PWM brightness control takes effect. This preliminary activation ensures that the necessary voltage and current are already available when brightness control begins, eliminating the start-up delay.
2Adaptability or versatility
If the LED driver IC is turned on/off for brightness control, then PWM driving is achieved, but linearity and dynamic range are degraded at higher frequencies
Solution Approach 1:
The patent separates the on/off control function from the brightness control function by creating distinct signal paths. The enabling signal EN handles on/off control while the PWM signal handles brightness control. This segmentation allows the LED driver IC to remain continuously on during brightness control, avoiding the repeated start-up shutdown cycles that cause time delays and degrade linearity at higher PWM frequencies.
Solution Approach 2:
The enabling signal EN acts as an intermediary that activates the reference voltage and current supplies in advance, allowing the PWM brightness control to operate without repeatedly starting and stopping the LED driver IC. This intermediary mechanism maintains the IC in a stable on state, improving linearity and dynamic range.
Data Source
AI summary
A load driving device according to the present invention is provided with: an enabling control section generating an enabling signal from an externally inputted PWM signal; and a load driving section that is turned on/off according to the enabling signal, and that PWM-drives the load according to the PWM signal.