Multi-function Pin Control Chip for LED Backlight Power Conversion
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Solution Overview
Problem
The increasing use of LED backlight sources in LCDs has led to a need to reduce the number of pins in control chips while maintaining normal operation, driven by considerations of product volume and manufacturing cost.
Innovation Solution
A power conversion apparatus with a control chip that integrates a multi-function pin to receive both dimming and feedback signals, allowing the control chip to determine whether to generate a PWM signal based on the dimming signal's duty ratio, and includes additional circuits for current and overvoltage detection, enabling the chip to enter a low power mode when necessary, thus reducing the number of pins required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of pins on the control chip is decreased, then manufacturing cost and product volume are improved, but the complexity of signal routing and pin functionality increases
Solution Approach 1:
The patent implements a multi-function pin that can operate in different modes: receiving dimming signals when the duty ratio is above a threshold, and receiving feedback signals when the duty ratio is below the threshold. This allows a single pin to replace what would traditionally require separate dedicated pins, thereby reducing the total pin count while maintaining full functionality.
Solution Approach 2:
The patent employs dynamic pin configuration where the function of the multi-function pin changes based on the duty ratio of the received signal. The control chip dynamically switches between interpreting the pin input as a dimming signal or a feedback signal, allowing adaptive reuse of the same physical pin for different purposes during operation.
2Quantity of substance
If the control chip integrates multiple functions into fewer pins, then the number of pins is reduced, but the difficulty of signal detection and processing increases
Solution Approach 1:
The patent incorporates a feedback mechanism where the control chip monitors the duty ratio of signals received on the multi-function pin and adjusts its interpretation accordingly. The system uses the duty ratio as a feedback parameter to determine whether the pin is receiving a dimming signal or a feedback signal, enabling automatic adaptive function switching without external intervention.
Solution Approach 2:
The patent changes the operational parameter (duty ratio threshold) to distinguish between different signal types on the same pin. By comparing the duty ratio against a predetermined threshold, the control chip can differentiate between dimming signals and feedback signals, simplifying the detection logic while reducing pin count.
3Use of energy by moving object
If the control chip enters low power mode by stopping PWM signal generation, then energy consumption is reduced, but the ability to control light-emitting unit dynamically is limited
Solution Approach 1:
The patent implements periodic monitoring of the multi-function pin signal duty ratio, allowing the control chip to dynamically switch between active PWM generation mode and low-power mode. This periodic assessment enables the system to enter sleep mode when full control is not needed, while maintaining the ability to quickly resume full functionality when required.
Solution Approach 2:
The control chip autonomously determines when to enter or exit low-power mode by self-monitoring the duty ratio of signals on the multi-function pin. The system serves itself by automatically adjusting its power state based on operational requirements, eliminating the need for external power management control while optimizing energy consumption.
Data Source
AI summary
A power conversion apparatus including a power conversion circuit, a light-emitting unit and a control chip is provided. The control chip has a multi-function pin and a feedback pin, where the multi-function pin and the feedback pin respectively receive a dimming signal and a feedback signal reflecting an output current of the light-emitting unit, and the control chip determines whether to generate a PWM signal to a power switch of the power conversion circuit according to the dimming signal and the feedback signal based on a duty ratio of the dimming signal.