LED Driving Circuit High-Frequency Dimming Control
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Solution Overview
Problem
Conventional LED driving IC chips malfunction when operating at high-frequency dimming frequencies beyond 20 KHz due to their inability to correspondingly operate with dimming control signals within the 20-200 KHz range.
Innovation Solution
An LED driving circuit with a control logic circuit, dimming circuit, and counter that receives input signals on an enable pin, asserts internal enable signals for activation, and de-activates the circuit when the enable signal is de-asserted for a predetermined period, allowing for effective control of current flowing into LEDs across various frequency ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the LED driving chip operates at high-frequency dimming frequencies (20-200 KHz), then the dimming control capability is improved, but the chip malfunctions due to inability to correspondingly operate with dimming control signals
Solution Approach 1:
The patent implements dynamic frequency identification and adaptive response by the counter circuit. The system dynamically adjusts its operating mode based on the detected frequency range of the input signal, switching between dimming control mode (2-20 KHz) and enable signal mode (20-200 KHz). This dynamic adaptation resolves the contradiction by enabling the chip to reliably operate across different frequency ranges without malfunction.
Solution Approach 2:
The patent changes the interpretation parameter of the input signal based on frequency characteristics. The counter identifies whether the input signal frequency falls within the dimming range (2-20 KHz) or the enable signal range (20-200 KHz), and the system accordingly changes its operational parameters. This parameter-based differentiation allows the same enable pin to support both dimming control and high-frequency enable functions without causing malfunctions.
2Adaptability or versatility
If the enable pin is used for receiving dimming control signals within 2-20 KHz, then the dimming function is achieved, but the chip cannot correspondingly operate when dimming is performed within 20-200 KHz frequency range
Solution Approach 1:
The patent performs preliminary frequency identification and classification before the main control action. The counter circuit预先 (in advance) determines whether the input signal is a dimming signal or an enable signal based on its frequency characteristics. This preliminary identification simplifies subsequent operation by pre-establishing the correct operational mode, eliminating the need for complex real-time signal type detection during normal operation.
Solution Approach 2:
The counter acts as an intermediary component between the enable pin and the control logic circuit. It mediates the signal interpretation process by filtering and classifying incoming signals based on frequency, then presenting the appropriate signal type to the control logic. This intermediary function simplifies the overall system operation by handling the complex frequency analysis task separately from the main control functions.
Data Source
AI summary
An LED driving circuit includes a control logic circuit, a dimming circuit and a counter. The control logic circuit is electrically coupled to an enable pin for receiving an input signal, and asserts an internal enable signal for activating the LED driving circuit. The dimming circuit is electrically coupled to the enable pin and outputs a control signal for controlling current flowing into at least one load connected to the LED driving circuit. The counter identifies the input signal based on a clock signal and asserts a detection signal for informing the control logic circuit of de-asserting the internal enable signal to de-activate the LED driving circuit when identifying the input signal as the enable signal being de-asserted for a predetermined period of the clock signal. A method of controlling an LED driving circuit is also disclosed herein.