Power Supply Circuit Reference Voltage Selection
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Solution Overview
Problem
Existing power supply circuits face challenges in maintaining stable output voltage due to variations in input voltage, leading to deteriorated line regulation and power supply ripple rejection characteristics.
Innovation Solution
A power supply circuit that selectively generates a reference voltage based on either the input voltage or the output voltage, using a changeover switch and switch control circuit to ensure the reference voltage remains stable, thereby improving line regulation and power supply ripple rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the reference voltage is generated based on the input voltage, then the circuit structure is simple, but the output voltage varies when the input voltage varies, deteriorating line regulation characteristics
Solution Approach 1:
The patent applies dynamics by making the reference voltage generation source selectable rather than fixed. The error amplifier can dynamically switch between using input voltage or output voltage as the reference voltage source depending on which provides better stability. This dynamic selection resolves the contradiction by adapting the circuit behavior to different operating conditions, improving line regulation without requiring a completely complex circuit structure.
Solution Approach 2:
The patent changes the parameter of reference voltage source selection. Instead of using a fixed reference voltage generation method, the system can switch between different voltage sources (input voltage or output voltage) based on which provides better output stability. This parameter change allows the circuit to maintain good line regulation characteristics while keeping the overall structure relatively simple.
2Reliability
If the reference voltage is generated based on the output voltage, then the line regulation characteristics improve, but the circuit structure becomes more complex
Solution Approach 1:
The error amplifier is designed with multi-functionality, capable of accepting either input voltage or output voltage as its reference voltage source. This universal design allows the same circuit component to serve different functions depending on the operating conditions, improving line regulation characteristics without proportionally increasing circuit complexity.
3Ease of manufacture
If a fixed reference voltage generation method is used, then the circuit is simple to design, but the power supply ripple rejection characteristics are poor when input voltage varies
Solution Approach 1:
The patent makes the reference voltage source dynamic rather than fixed. The error amplifier can switch between using input voltage or output voltage as the reference depending on which provides better ripple rejection. This dynamic approach maintains design simplicity while significantly improving power supply ripple rejection characteristics under varying input voltage conditions.
Data Source
AI summary
A power supply circuit includes a transistor disposed between an input terminal to which an input voltage is applied and an output terminal to which an output voltage is applied, and an error amplifier configured to compare a feedback voltage varied based on the output voltage and a reference voltage, and control the transistor based on a result of the comparison, the reference voltage being generated by selectively using the input voltage or the output voltage.