LED Driving Circuit PWM Frequency Control

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Solution Overview

Problem

Existing LED display devices face challenges in maintaining high display resolution due to limitations in PWM frequency adjustment, which can lead to flicker phenomena and reduced brightness control precision.

Innovation Solution

The proposed LED driving circuit stores a multiplier frequency indicator in a register and performs internal computation to control PWM operations, eliminating the need for external data communication to adjust PWM frequency, thereby improving precision and reducing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If PWM frequency is adjusted by adding data bits to external communication protocol, then PWM frequency can be changed, but display resolution decreases

Engineering Contradiction:

ImprovePWM frequency adjustment capabilityVSAvoiddisplay resolution

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by pre-storing multiple PWM frequency indicators in the register before operation. The microcontroller unit selects the appropriate frequency indicator based on driving requirements without needing to communicate frequency adjustment data externally. This eliminates the trade-off between frequency adjustment capability and display resolution.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If PWM frequency is increased to improve brightness control precision, then brightness control precision improves, but flicker phenomenon occurs

Engineering Contradiction:

Improvebrightness control precisionVSAvoidflicker phenomenon

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by providing multiple PWM frequency indicators (e.g., 1x, 2x, 4x, 8x, 16x frame rate) that can be selected based on the required brightness control precision. The system adjusts the frequency multiplier parameter to achieve the desired balance between precision and flicker reduction without requiring external data communication for frequency adjustment.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If external oscillator is used for PWM generation, then PWM frequency can be adjusted, but data communication bandwidth is reduced

Engineering Contradiction:

ImprovePWM frequency flexibilityVSAvoiddata communication efficiency

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent applies self-service by enabling the LED driving circuit to autonomously select and implement PWM frequencies from pre-stored indicators without requiring external frequency adjustment data. The microcontroller unit internally manages the frequency selection based on driving requirements, eliminating the need for external oscillator data communication and preserving communication bandwidth for other purposes.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS12223884B2LED driving circuit and its driving method

Publication Date: 2025.02.11 LX SEMICON CO LTD

AI summary

An LED driving circuit adjusts a PWM driving frequency in light emitting diode driving, and changes a PWM frequency of an LED driving circuit in response to a frequency of a PWM clock signal delivered externally or internally.