On-time Control Module Stabilizes Switching Frequency
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Solution Overview
Problem
Conventional DC-DC switching regulators face challenges in stabilizing the switching frequency due to variations in load current and conduction resistance, requiring large capacitors for feedback compensation, which increases circuit area and complexity.
Innovation Solution
An on-time control module comprising an average duty voltage generating circuit and an on-time controller, which generates a control signal with an on-time related to the duty based on input voltage and average duty voltage, allowing for stabilization of the switching frequency by correlating the on-time with the duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional feedback compensation with large capacitors is used to stabilize switching frequency, then switching frequency stability is improved, but circuit area and complexity increase
Solution Approach 1:
The patent extracts the frequency stabilization function from the conventional feedback compensation circuit and implements it through a simplified on-time control mechanism. By generating on-time directly proportional to the duty cycle through voltage division and integration, the complex feedback compensation network with large capacitors is eliminated, achieving frequency stability through a more straightforward control approach.
Solution Approach 2:
The patent changes the control parameter from conventional voltage feedback to on-time control directly proportional to duty cycle. By making the on-time parameter vary linearly with the duty cycle parameter, the switching frequency is stabilized without requiring complex feedback compensation circuits, thus reducing circuit complexity while maintaining frequency stability.
2Stability of the object's composition
If conventional feedback compensation with large capacitors is used to stabilize switching frequency, then switching frequency stability is improved, but circuit area increases
Solution Approach 1:
The patent removes the large compensation capacitors from the circuit by extracting the frequency stabilization function and implementing it through on-time control. The duty cycle-proportional on-time generation eliminates the need for large capacitive elements, significantly reducing the circuit layout area while maintaining switching frequency stability.
3Device complexity
If fixed on-time is used with fixed duty cycle, then circuit complexity is reduced, but switching frequency varies with load current and conduction resistance
Solution Approach 1:
The patent implements dynamic on-time adjustment by making the on-time parameter dynamically proportional to the duty cycle through voltage division and integration. This dynamic relationship ensures that as load current and conduction resistance change, the on-time automatically adjusts to maintain constant switching frequency, achieving frequency stability without increasing circuit complexity.
Solution Approach 2:
The patent employs implicit feedback by integrating the duty cycle-proportional voltage to generate the on-time control signal. This feedback mechanism automatically adjusts the on-time based on the duty cycle variations caused by load changes, thereby stabilizing the switching frequency while maintaining a relatively simple circuit structure.
Data Source
AI summary
The present invention discloses an on-time control module for compensating a switching frequency in a switching regulator. The on-time control module includes an average voltage generating circuit, for generating an average voltage related to a duty according to an input voltage and the duty, and an on-time controller, for generating a control signal of an on-time related to the duty according to the input voltage and the duty voltage.