Asymmetrical Half-Bridge Flyback Brown-In/Out Voltage Sensing
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Solution Overview
Problem
Existing switching conversion circuits for asymmetrical half-bridge flyback topologies require additional monitoring circuits to implement brown in/out functions, increasing system costs and complexity.
Innovation Solution
A switching conversion circuit that time-division multiplexes existing pins to detect working voltages, eliminating the need for additional monitoring circuits and reducing peripheral circuits and system costs, while maintaining accurate brown in/out control through precise voltage detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional monitoring circuits are added to implement brown in/out function, then voltage detection accuracy is improved, but device complexity and system cost increase
Solution Approach 1:
The existing pins (VBUS pin and SW pin) are made multi-functional by time-division multiplexing. The VBUS pin is used both for its original power supply function and for detecting input voltage to determine brown in/out states. The SW pin is used both for switching operation and for detecting working voltage during different time periods. This eliminates the need for additional monitoring circuits while maintaining accurate voltage detection.
Solution Approach 2:
The circuit uses its own existing components and pins to perform the brown in/out detection function. The controller leverages the already-present VBUS and SW pins, along with existing switching transistors and capacitors, to detect voltages and control power supply states without requiring external monitoring circuits. The system essentially serves itself by repurposing existing resources.
2Adaptability or versatility
If additional monitoring circuits are added to implement brown in/out function, then voltage detection capability is improved, but manufacturing cost increases
Solution Approach 1:
The VBUS pin and SW pin are designed to serve multiple functions. The VBUS pin handles both power input and voltage detection for brown in/out control. The SW pin performs both switching operations and voltage detection during different time periods. This multi-functionality reduces the bill of materials and eliminates additional components, thereby reducing manufacturing costs.
Solution Approach 2:
The brown in/out detection function is merged with the existing power supply and switching functions. The same pins and circuit components that handle power conversion and switching are also used for voltage detection. This consolidation combines multiple functions into existing circuit elements, reducing overall system complexity and manufacturing cost.
3Device complexity
If existing pins are time-division multiplexed for voltage detection, then peripheral circuits are reduced, but control complexity increases
Solution Approach 1:
The controller implements periodic sampling of voltages at different time periods. During first time periods, the VBUS pin detects input voltage. During second time periods, the SW pin detects working voltage. This periodic action is coordinated with the switching cycles of the power converter, creating a rhythmic detection pattern that simplifies timing control while reducing peripheral circuit requirements.
Solution Approach 2:
The controller uses feedback from the detected voltages to adjust switching transistor operations and determine brown in/out states. The detected working voltage and input voltage are fed back to the controller, which then controls the switching transistors accordingly. This feedback mechanism provides a clear control logic that manages the time-division multiplexing operations.
Data Source
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AI summary
This application provides a switching conversion circuit, including: a power module, supplying power to a switching conversion module and an IC controller; and the switching conversion module is an asymmetrical half-bridge flyback structure and includes at least a first switching transistor, a second switching transistor, a first capacitor, and a transformer. The first switching transistor and the second switching transistor are connected in series at both terminals of the power module. A primary-side winding of the transformer is coupled at both terminals of the first switching transistor by using the first capacitor. The transformer includes a first secondary-side winding and a second secondary-side winding, and the first secondary-side winding of the transformer is coupled to a load. The IC controller turns on the first switching transistor or the second switching transistor based on a value of a first voltage, so that the switching conversion module enters an operating state to supply power to the load; and turns off the first switching transistor and the second switching transistor based on a value of a second voltage, so that the switching conversion module stops supplying power to the load.