Synchronous Rectification Control Circuit for Power Supply Efficiency
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Solution Overview
Problem
Conventional synchronous rectification switching power supplies face inefficiencies due to cross-conduction phenomena and complex control of synchronous rectifier switches, which hinder further improvements in power efficiency, and existing solutions often increase circuit size and cost.
Innovation Solution
A control and drive circuit for synchronous rectification switching power supplies that includes a primary side switch controller, a logic circuit, a converting circuit, and a synchronous rectifier switch controller, where the phases of the primary side switch control signal and the synchronous rectifier switch control signal are synchronized or inverted based on the topology, using differential conversion and zero-crossing detection to control the switches effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional synchronous rectification control is used, then power efficiency can be improved, but cross-conduction phenomena occur and control complexity increases
Solution Approach 1:
The patent extracts the control signal generation function from the secondary side and relocates it to the primary side. The primary side switch controller generates both the primary side switch control signal and the synchronous rectifier switch control signal, eliminating the need for complex secondary side control circuits and reducing overall control complexity while maintaining efficiency.
Solution Approach 2:
The patent uses preliminary action by generating the synchronous rectifier switch control signal in advance on the primary side based on the primary side switch control signal. This allows the control signals to be prepared before needed, avoiding real-time complex control on the secondary side and preventing cross-conduction issues.
2Loss of energy
If synchronous rectification is implemented, then power losses are reduced, but circuit complexity and cost increase
Solution Approach 1:
The patent merges the control functions for the primary side switch and the synchronous rectifier switch into a single primary side switch controller. This consolidation integrates multiple control functions into one device, reducing circuit complexity and component count while maintaining the power loss reduction benefits of synchronous rectification.
3Ease of operation
If traditional control signals are used, then switching control is simple, but cross-conduction cannot be avoided
Solution Approach 1:
The patent implements feedback by using the primary side switch control signal as the basis for generating the synchronous rectifier switch control signal. This feedback mechanism ensures that the rectifier switch is controlled based on the actual switching state of the primary side, preventing cross-conduction while maintaining simple switching control through the integrated controller.
Data Source
AI summary
Disclosed herein are control and drive circuits and methods for synchronous rectification switching power supply bias voltage generating circuits configured for a switching power supply. In one embodiment, a control and drive circuit can include: (i) a primary side switch controller configured to generate a primary side switch control signal; (ii) a logic circuit configured to generate a first control signal based on the primary side switch control signal; (iii) a converting circuit configured to generate a second control signal based on the first control signal; and (iv) a synchronous rectifier switch controller configured to generate a synchronous rectifier switch control signal based on the second control signal such that phases of the primary side switch control signal and the synchronous rectifier switch control signal are the same or inverse based on a topology of the synchronous rectification switching power supply.