LED Driving Chip Single-Stage AC/DC Power Conversion
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Solution Overview
Problem
Existing LED driving chips require multiple pins and stages of power conversion, leading to low power efficiency and high packaging costs due to the mismatched efficiency of AC/DC and DC/DC power circuits, and a large pin count that occupies more space.
Innovation Solution
An LED driving chip with eight or six pins, incorporating a current regulating circuit, current control circuit, feedback voltage control circuit, and protection circuit that selectively outputs currents and feedback voltages, and adjusts based on voltage differences to optimize power delivery and reduce pin count, using a single-stage AC/DC power supply to generate DC power voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional LED driving chip uses a two-stage power circuit (AC/DC and DC/DC), then the system can operate with both power conversion stages, but the overall power efficiency deteriorates due to the product of two efficiency values being lower than a single stage
Solution Approach 1:
The patent removes the DC/DC power conversion stage from the traditional two-stage AC/DC+DC/DC power circuit, retaining only the AC/DC stage. This extraction eliminates the second efficiency loss while maintaining the necessary power conversion functionality through direct AC/DC conversion with integrated LED string control
Solution Approach 2:
The patent combines the LED string driving control functions directly into the AC/DC power conversion circuit. The current regulating circuits and control logic that were previously separate DC/DC stages are now integrated within the AC/DC conversion architecture, merging power conversion and LED control into a unified system
2Adaptability or versatility
If a conventional LED driving chip is designed to drive four LED strings, then the driving capability is sufficient, but the pin count increases to at least 16 pins, causing high packaging cost and larger area occupation
Solution Approach 1:
The patent implements multi-functional pins that can dynamically switch between different LED string control functions. Each pin can serve multiple purposes depending on the operational mode, allowing the chip to drive four LED strings with only eight pins by sharing control signals and multiplexing pin functions
Solution Approach 2:
The patent employs dynamic pin function assignment where pins can change their operational role based on real-time requirements. The control circuits dynamically configure pin functions to accommodate different LED string configurations, enabling adaptability without increasing physical pin count
Data Source
AI summary
A light emitting diode driving chip includes: a current regulating circuit arranged to selectively outputting four currents to four pins respectively; a current control circuit coupled to the current regulating circuit and a fifth pin, arranged to receive an adjusting signal at the fifth pin to control the four currents; a feedback voltage control circuit arranged to output a feedback voltage to a sixth pin according to a first specific voltage selected from four voltages corresponding to the four pins; and a protection circuit arranged to determine whether a voltage difference between a second specific voltage selected from the four voltages and the first specific voltage is larger than a threshold value. If the first specific voltage is larger than the threshold value, the protection circuit controls the current regulating circuit to stop conducting current to a specific pin corresponding to the first specific voltage.