Integrated Circuit for AC-DC Converter Noise Immunity
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Solution Overview
Problem
Existing AC-DC converters face challenges in accurately detecting voltages from auxiliary coils due to noise and the need for precise adjustment of coil turns, which affects the operation of detection circuits and power supply voltages.
Innovation Solution
The integrated circuit includes specific terminals for receiving coil voltages and feedback voltages, along with detection and control circuits that manage transistor switching based on these voltages and a reference threshold, enabling accurate voltage detection and overcurrent determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power supply voltage is generated based on the voltage from the auxiliary coil, then the integrated circuit can operate with the available power supply, but noise and other interference are superimposed on the voltage, causing significant changes in the power supply voltage
Solution Approach 1:
The patent separates the power supply voltage generation function from the detection function by providing dedicated terminals. The VCC terminal receives the auxiliary coil voltage for power supply, while the VD terminal specifically receives the detection voltage for over-power detection. This segmentation allows the detection circuit to operate independently from noise affecting the power supply voltage.
Solution Approach 2:
The patent introduces an intermediary detection terminal (VD) that mediates between the auxiliary coil voltage and the detection circuit. This intermediary terminal provides a clean detection path that is isolated from the noise and fluctuations present in the main power supply voltage, enabling accurate over-power detection without being affected by power supply instability.
2Adaptability or versatility
If the number of turns of the auxiliary coil is set in consideration of other circuits coupled to the power supply terminal, then the power supply requirements are met, but it becomes difficult to appropriately operate the detection circuit based on the voltage at the power supply terminal
Solution Approach 1:
The patent divides the voltage reception functions into separate terminals: the VCC terminal for power supply voltage reception and the VD terminal for detection voltage reception. This segmentation allows the auxiliary coil to be designed to meet power supply requirements while simultaneously providing a dedicated clean voltage path for the detection circuit, eliminating the trade-off between power supply compatibility and detection precision.
Solution Approach 2:
The auxiliary coil serves multiple functions simultaneously: it provides power supply voltage through the VCC terminal and provides detection voltage through the VD terminal. This multi-functionality allows a single coil design to satisfy both power supply requirements and detection circuit requirements without compromise.
3Extent of automation
If a detection circuit detects the power of a load based on the level of the power supply voltage at the power supply terminal, then load power detection is achieved, but the noise superimposed on the power supply voltage significantly changes the detection accuracy
Solution Approach 1:
The patent introduces a dedicated VD terminal as an intermediary between the auxiliary coil and the detection circuit. This intermediary provides a clean detection voltage path that is isolated from the noise present in the power supply voltage at the VCC terminal, enabling accurate automatic load power detection without being affected by power supply fluctuations.
Solution Approach 2:
The patent segments the detection function from the power supply function by providing a separate VD terminal for detection voltage. This allows the detection circuit to accurately measure load power based on a clean detection voltage while the power supply voltage may contain noise without affecting detection accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution allows for precise detection and control of output voltages and currents, improving the reliability and efficiency of AC-DC converters by reducing noise interference and adjusting coil settings effectively.
Implementation Method 1
a first diode configured to rectify a coil voltage across the auxiliary coil
Implementation Method 2
a first capacitor coupled to the first terminal, and configured to be charged with a current flowing through the first diode
Implementation Method 3
a second diode configured to rectify the coil voltage; and a second capacitor coupled to the third terminal, and configured to be charged with a current flowing through the second diode
Data Source
AI summary
An integrated circuit for a power supply circuit that includes a transformer and a transistor. The integrated circuit includes a first terminal receiving a voltage corresponding to a coil voltage across an auxiliary coil of the transformer when the transistor is off, a second terminal receiving a feedback voltage corresponding to an output voltage of the power supply circuit, a third terminal receiving a voltage that corresponds to a current flowing through the transistor and the coil voltage respectively when the transistor is on and off, a detection circuit configured to detect whether the voltage at the third terminal when the transistor is off is lower than a reference voltage, and a control circuit configured to control switching of the transistor based on the feedback voltage, the voltage at the third terminal when the transistor is on, and a detection result of the detection circuit.