Adaptive Constant On-Time Converter Transient Response
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Solution Overview
Problem
Conventional constant on-time converters exhibit poor transient response when load changes occur, leading to excessive voltage fluctuations during instantaneous transitions from light to heavy loads or vice versa, due to fixed clock signal characteristics.
Innovation Solution
The proposed constant on-time converter incorporates a first and second compensation circuit and an on-time generator to adaptively adjust the on-time of the clock signal, allowing for dynamic adjustments in inductive current based on feedback voltage comparisons, thereby enhancing transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clock generator uses a fixed minimum period clock signal for over current protection, then the converter maintains reliable operation, but the transient response deteriorates when load changes instantaneously
Solution Approach 1:
The patent applies dynamics by making the clock signal period variable rather than fixed. The on-time generator dynamically adjusts the clock signal period based on the difference between reference voltage and feedback voltage. When load changes cause voltage deviation, the system automatically extends or reduces the clock period to provide appropriate current adjustment speed, thus improving transient response while maintaining over-current protection through voltage comparison control
2Stability of the object's composition
If the clock signal has a constant on-time, then the converter operates stably under normal conditions, but the output voltage experiences excessive fluctuation during load transitions
Solution Approach 1:
The patent applies parameter changes by modifying the clock signal period parameter dynamically. Instead of using a fixed constant on-time, the system changes the clock period parameter based on voltage deviation magnitude. When output voltage deviates from reference, the period parameter is extended to allow greater current adjustment; when voltage is stable, the parameter returns to normal timing, thus achieving both stability and adaptability
3Ease of operation
If the converter uses a periodic oscillation clock signal, then the switching operation is simplified, but the transient response time increases during load changes
Solution Approach 1:
The patent applies periodic action by using voltage comparison pulses to periodically extend the clock signal period when needed. The system maintains normal periodic oscillation for simplified switching control, but superimposes periodic extension actions when voltage deviation is detected. This allows the system to keep the simplicity of periodic oscillation while adding transient response capability through conditional period extension
Data Source
AI summary
The present disclosure provides a constant on-time converter having fast transient response, which adaptively adjusts an on-time and an off-time by a first compensation circuit and a second compensation circuit, to accordingly adjust an inductive current. When a load converts a light loading into a heavy loading, the constant on-time converter adaptively adjusts the on-time of the clock signal. When the load converts a heavy loading into a light loading, the constant on-time converter adaptively adjusts the off-time of the clock signal. Therefore, the output voltage can be adjusted rapidly in response to different load changes to enhance the transient response of the output voltage.