Power Converter Control Circuit Pin Reduction via Signal Multiplexing
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Solution Overview
Problem
Traditional power converter control circuits with boost-up functions face challenges in reducing pin count while maintaining current detection and over-voltage protection capabilities, especially in applications like LED backlight driving circuits.
Innovation Solution
A power converter control circuit design that integrates a power converter and control circuit, utilizing a power saving device and transistor with a multi-function input, over-current detection, and over-voltage detection circuits, combining current detection and over-voltage protection signals into a single pin, and employing pulse-width modulation for control, allowing for efficient voltage and current management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional separate pins are used for current detection and over-voltage protection, then detection accuracy is improved, but pin count increases
Solution Approach 1:
The patent applies multi-functionality by designing a single pin that can detect both over-current and over-voltage conditions. The pin is configured to receive different signals depending on the operational state: during the switching on-state it detects over-current through the sense resistor, and during the switching off-state it detects over-voltage through the feedback network. This eliminates the need for separate pins while maintaining detection capabilities for both parameters.
2Reliability
If multiple separate circuits are used for current detection and over-voltage protection, then functional reliability is improved, but circuit complexity increases
Solution Approach 1:
The patent employs periodic action by utilizing the periodic switching nature of the power converter circuit. The single detection pin operates in different modes during different phases of the switching cycle: during the on-state it measures current through the sense resistor, and during the off-state it measures voltage through the feedback network. This time-division multiplexing approach maintains functional reliability by sequentially performing both detection functions without requiring simultaneous separate circuits.
Solution Approach 2:
The detection circuit exhibits dynamic behavior by changing its measurement mode based on the switching state. The pin dynamically switches between current detection mode (when the switch is on) and voltage detection mode (when the switch is off). This dynamic operation allows a single static pin to perform multiple detection functions that would traditionally require separate static circuits, thereby reducing overall circuit complexity while maintaining reliability.
Data Source
AI summary
Disclosed is a power converter control circuit, comprising at least a power converter circuit and a control circuit. The power converter circuit is able to boost up an input voltage into a greater driving voltage and supply it to the driven device. Moreover, the power converter circuit is also able to generate a voltage signal and a current-sense signal separately, and then combine them into a joint voltage/current-sense signal. The control circuit receives the joint voltage/current-sense signal and resolves it into an over-voltage signal and a current-sense signal with the aid of a modulation signal. The two signals are separately fed into an over-voltage protection device and an over-current protection device for comparison; the outcomes are utilized to execute the over-voltage protection and the over-current protection.