LED Driving Circuit with Periodic PWM Sampling
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Solution Overview
Problem
Existing driving circuits for light emitting diodes (LEDs) consume high power due to continuous sampling and calculation of PWM input signals, which affects the efficiency and longevity of LED brightness control.
Innovation Solution
A driving circuit that utilizes a local clock signal with suspended oscillation periods to reduce power consumption, where the local clock signal is generated based on a global clock signal and used to sample and calculate duty ratios of PWM input signals only during active periods, thereby minimizing power usage during inactive periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the local clock signal continuously samples and calculates PWM input signals, then the brightness control accuracy is maintained, but the power consumption increases
Solution Approach 1:
The local clock signal is configured to oscillate periodically with suspended oscillation periods rather than continuously. During active periods, the clock signal samples and calculates PWM duty ratios to update brightness codes. During suspended periods, the clock signal stops oscillating to reduce power consumption. This periodic activation pattern maintains brightness control accuracy when needed while significantly reducing overall power consumption of the driving circuit.
2Reliability
If the local clock signal oscillates continuously, then the PWM sampling is uninterrupted, but the power consumption increases
Solution Approach 1:
The local clock signal operates in periodic cycles with active oscillation periods followed by suspended oscillation periods. During active periods, PWM sampling and brightness code updates occur to ensure reliable brightness control. During suspended periods, the clock signal stops to conserve power. This periodic operation maintains reliability during active phases while reducing overall power consumption through strategic suspension periods.
3Speed
If the driving circuit operates continuously without suspension, then the brightness response is immediate, but the power consumption and heat generation increase
Solution Approach 1:
The driving circuit operates periodically with active periods for PWM sampling and brightness code generation, followed by suspended periods where the local clock signal stops oscillating. During active periods, the circuit responds immediately to PWM input changes to maintain brightness response speed. During suspended periods, power consumption and heat generation are reduced. This periodic operation pattern balances response speed with energy efficiency.
Data Source
AI summary
A driving circuit, for providing a driving current to a light emitting diode, includes a PWM demodulator, a current source and a local clock generator. The PWM demodulator is configured to sample a PWM input signal in reference with a local clock signal and generate a brightness code according to a duty ratio of the PWM input signal. The current source is coupled with the PWM demodulator and the light emitting diode. The current source is configured to generate the driving current with a current amplitude according to the brightness code. The local clock generator is configured to generate the local clock signal according to a global clock signal during a first cycle period of successive cycle periods of the PWM input signal. The local clock generator suspends oscillation of the local clock signal during a second cycle period of the successive cycle periods of the PWM input signal.