Flyback Power Converter Multi-Function Pin Detection
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Solution Overview
Problem
Existing power conversion apparatuses with PWM control chips require multiple isolated detection pins for over temperature and over voltage protection, increasing production costs and complexity.
Innovation Solution
A flyback-based power conversion apparatus with a control chip and detection auxiliary circuit that uses a multi-function detection pin to execute over temperature and over voltage protection, reducing the need for multiple detection pins by utilizing different detection phases and a valley voltage detection unit to determine PWM signal transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple isolated detection pins are used for over temperature and over voltage protection, then detection reliability is improved, but device complexity and production cost increase
Solution Approach 1:
The patent applies multi-functionality by designing a single detection pin that can perform both over temperature protection and over voltage protection functions. The detection auxiliary circuit uses different detection phases to enable the same pin to detect different parameters (temperature during first detection phase, voltage during second detection phase), thereby reducing the number of pins required while maintaining comprehensive protection capability
Solution Approach 2:
The patent implements periodic action through the detection auxiliary circuit that alternates between different detection phases. The circuit periodically switches between over temperature detection and over voltage detection modes, allowing a single pin to sequentially perform multiple detection functions. This periodic switching enables one pin to replace what would traditionally require multiple dedicated pins
2Measurement precision
If multiple isolated detection pins are used for protection functions, then detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The detection auxiliary circuit enables a single pin to serve multiple detection purposes through time-division multiplexing. By configuring the pin to detect temperature during the first detection phase and voltage during the second detection phase, the circuit achieves comprehensive protection functionality with reduced pin count, directly lowering manufacturing complexity and cost while preserving detection accuracy through dedicated detection circuits for each parameter
3Device complexity
If a multi-function detection pin is used, then device complexity is reduced, but detection precision may deteriorate
Solution Approach 1:
The detection auxiliary circuit applies segmentation by dividing the detection process into distinct phases - a first detection phase for temperature monitoring and a second detection phase for voltage monitoring. This temporal segmentation ensures that each detection function operates independently with dedicated circuit pathways, preventing signal interference and maintaining high detection precision for both parameters despite using a shared pin
Solution Approach 2:
The circuit employs periodic switching between detection modes to maintain precision. By alternately activating temperature detection and voltage detection in separate phases, the system ensures that each detection function receives full attention without interference from the other, preserving measurement accuracy while achieving pin consolidation
Data Source
AI summary
A power conversion apparatus including a flyback power conversion circuit, a control chip and a detection auxiliary circuit is provided. The flyback power conversion circuit receives and converts an AC input voltage into a DC output voltage. The control chip generates a PWM signal in response to a power supply requirement to control operations of the flyback power conversion circuit, and the control chip has a multi-function detection pin. The detection auxiliary circuit assists the control chip to obtain an auxiliary voltage related to the DC output voltage via the multi-function detection pin, and thereby determines a transition time of the PWM signal according to the auxiliary voltage. Besides, the detection auxiliary circuit assists the control chip to execute detections of an over temperature protection (OTP) and an over voltage protection (OVP) via the multi-function detection pin respectively within first and second detection phases.