Synchronous Rectification Control Circuit for Reverse Surge Suppression
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Solution Overview
Problem
The existing synchronous rectification circuits in power supply technology face reliability issues due to reverse current surges, which are addressed by adding anti-reverse diodes or MOS transistors, but these solutions increase system cost and power consumption.
Innovation Solution
A control circuit that detects reverse surge currents and switches off switch tubes on the secondary side of the synchronous rectification circuit, using an obtaining module to identify voltage signals, a maintaining module to output control signals, and a control module to manage the switching, thereby suppressing reverse current surges without increasing system cost or power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anti-reverse diode or MOS transistor is added to the voltage input terminal of the switch tube rectification unit, then reverse current surge is prevented and reliability is improved, but system cost increases
Solution Approach 1:
The patent employs a feedback mechanism where the control circuit continuously monitors the voltage signal at the voltage input terminal of the switch tube rectification unit. When the voltage signal indicates reverse current surge (voltage becomes negative or exceeds threshold), the control circuit generates a control signal to switch off the switch tubes on the secondary side, thereby preventing damage. This feedback-based detection and response eliminates the need for additional anti-reverse diodes or MOS transistors in the main circuit.
Solution Approach 2:
The patent introduces a control circuit as an intermediary between the primary side and secondary side of the power supply. This control circuit acts as a mediator that detects reverse current conditions on the primary side and responds by controlling the switch tubes on the secondary side. This intermediary approach allows indirect protection without adding components directly in the main power path, thus avoiding increased system cost.
2Reliability
If anti-reverse diode or MOS transistor is added to the voltage input terminal of the switch tube rectification unit, then reverse current surge is prevented and reliability is improved, but power consumption increases
Solution Approach 1:
The control circuit uses feedback to detect reverse current conditions through voltage signal monitoring and only activates protection measures when reverse current surge is detected. This on-demand protection approach avoids continuous power consumption that would result from having anti-reverse diodes or MOS transistors permanently installed in the main circuit, thereby reducing overall power consumption while maintaining reliability.
3Loss of energy
If MOS transistors are used to replace diodes for synchronous rectification, then conduction loss is reduced and efficiency is improved, but reverse current surge occurs and reliability deteriorates
Solution Approach 1:
The patent maintains the MOS transistor-based synchronous rectification configuration for low conduction loss while adding a feedback-based control mechanism. The control circuit monitors the voltage signal and detects reverse current conditions, then responds by switching off the MOS transistors to prevent damage. This feedback approach allows the system to enjoy the efficiency benefits of MOS transistors during normal operation while protecting against reverse current surge-induced reliability issues.
Solution Approach 2:
The control circuit performs preliminary detection of reverse current conditions by monitoring the voltage signal before the reverse current surge can cause damage to the MOS transistors. When the voltage signal indicates impending reverse current surge, the control circuit proactively generates control signals to switch off the MOS transistors, preventing the harmful effect before it occurs. This preliminary action allows the MOS transistors to operate efficiently during normal conditions while protecting against reliability failures.
Data Source
AI summary
A control circuit, a control method, and a power supply device are provided. The control circuit includes an obtaining module, adapted to obtain a voltage signal from a reverse surge current when the reverse surge current appears on a primary side of a switch power circuit of a synchronous rectification circuit; a maintaining module, adapted to continuously output a first control signal in a preset first time period when the voltage signal is greater than a preset first voltage threshold; and a control module, adapted to control and switch off switch tubes of the secondary side of the switch power circuit of the synchronous rectification circuit according to the first control signal. Thus, a reverse current surge of the switch power circuit of the synchronous rectification circuit can be effectively suppressed, and the safety of a switch power supply of the synchronous rectification circuit can be effectively protected.