Switching Converter On-Time Control for Overshoot Suppression
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Solution Overview
Problem
Switching converters with constant on time (COT) control experience large overshoot in output voltage during load step-up events due to prolonged increased on time, leading to inefficient transient response and potential ringback issues.
Innovation Solution
A controller system comprising a transient sensing circuit, mode determining circuit, and on time regulating circuit that generates a transient voltage signal and mode signal to adjust the on time of the switch based on feedback voltage signals and threshold comparisons, effectively suppressing overshoot by dynamically regulating the switch's on time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the on time of the switch is increased to slow down the sharp drop in output voltage during a load step-up event, then the transient response speed is improved, but large overshoot in the output voltage occurs
Solution Approach 1:
The patent detects the transient state of the output voltage in advance and adjusts the on time of the switch before the overshoot occurs. By monitoring the output voltage and predicting the transient behavior, the control circuit proactively reduces the on time to prevent excess energy storage in the inductor, thereby avoiding overshoot while maintaining fast transient response.
Solution Approach 2:
The patent employs a feedback mechanism where the output voltage is continuously monitored and fed back to the control circuit. Based on the feedback signal, the control circuit dynamically adjusts the on time of the switch to maintain the output voltage within the desired range, preventing both excessive droop and overshoot during transient events.
2Stability of the object's composition
If the on time of the switch is increased to maintain output voltage during load step-up, then the output voltage stability is improved, but the inductor stores excess energy causing voltage ringback
Solution Approach 1:
The control circuit detects the transient state in advance and adjusts the on time before the inductor accumulates excess energy. By proactively reducing the on time during the transient period, the system prevents the inductor from storing too much energy that would cause voltage ringback, while still maintaining adequate output voltage stability.
Solution Approach 2:
The patent dynamically adjusts the on time of the switch based on the real-time transient state of the output voltage. Instead of using a fixed on time, the control circuit varies the on time duration according to the load conditions and output voltage behavior, optimizing both stability and preventing ringback effects.
Data Source
AI summary
A controller used in a switching converter having a switch and converting an input voltage into an output voltage having a transient profile. The controller includes a transient sensing circuit, a mode determining circuit and an on time regulating circuit. The transient sensing circuit generates a transient voltage signal indicative of the transient profile of the output voltage. The mode determining circuit receives the transient voltage signal and a first feedback voltage signal indicative of the output voltage, and generates a mode signal based on a first comparison between the first feedback voltage signal and a first threshold voltage and a second comparison between the transient voltage signal and a second threshold voltage. The on time regulating circuit generates an on time signal to regulate an on time of the switch based on the mode signal.