Switching Regulator Frequency Limitation Circuit
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Solution Overview
Problem
Switching power supplies with ultra-high switching frequencies face challenges in meeting EMI standards due to increased power loss and electromagnetic interference, which complicates compliance with EMI standards and affects the quality of power networks and connected devices.
Innovation Solution
A switching regulator with a frequency limitation circuit that utilizes a quasi-resonant control method and includes a frequency limitation circuit to set a minimum off time for the switch, limiting the switching frequency and reducing power loss by ensuring the switch remains off for a predetermined time after being turned off, thereby enhancing efficiency and reducing EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the switching frequency is increased to achieve high efficiency and small volume, then the efficiency and volume are improved, but the EMI and power loss increase
Solution Approach 1:
The patent introduces a frequency limitation circuit that enforces periodic action by setting a minimum off-time for the switching element. This creates a periodic pattern where the switch must remain off for at least a predetermined time period after each on-period, thereby limiting the maximum switching frequency and reducing EMI while maintaining efficient operation during normal conditions.
2Productivity
If the switching frequency is increased to achieve high efficiency and small volume, then the efficiency and volume are improved, but the power loss increases
Solution Approach 1:
The frequency limitation circuit implements periodic action by mandating a minimum off-time between switching cycles. This periodic constraint prevents excessively high switching frequencies that would generate excessive power loss, while allowing high-frequency operation during normal conditions to maintain efficiency and compact size.
3Productivity
If the switching frequency is increased, then the efficiency is improved, but the EMI standards compliance becomes difficult
Solution Approach 1:
The patent employs periodic action through the frequency limitation circuit that enforces a minimum off-time, creating a controlled periodic switching pattern. This approach limits the maximum switching frequency to levels that satisfy EMI standards while preserving the benefits of high-frequency switching during normal operation, thereby ensuring reliable compliance with EMI regulations.
Data Source
AI summary
A switching regulator with frequency limitation comprises a switch, a current sensing circuit, a voltage feedback circuit, a control circuit and a frequency limitation circuit. The current sensing circuit senses the current flowing through the switch and generating a current sensing signal representative of it. The voltage feedback circuit senses the output signal of the switching regulator and generates a feedback signal accordingly. The control circuit compares the current sensing signal with the feedback signal and turns off the switch based on the comparison result. The frequency limitation circuit is electrically coupled to the control circuit to limit the switching frequency of the switch.