Secondary-Side Synchronous Rectification Controller for Burst Mode Power Reduction
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Solution Overview
Problem
There is a continuous demand for reducing power consumption in AC/DC converters, particularly in standby or burst mode operations, where existing technologies do not adequately minimize power usage.
Innovation Solution
A synchronous rectification controller is introduced on the secondary side of an insulated synchronous rectification DC/DC converter, which includes a pulse generator, driver, and automatic shutdown circuit to suspend switching of the synchronous rectification transistor when the primary-side controller operates in burst mode, reducing switching losses and power consumption by operating the secondary-side circuit as a diode rectifier and shutting down parts of the circuit block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If synchronous rectification transistor switching is maintained during burst mode operation, then rectification function is preserved, but switching losses and power consumption increase
Solution Approach 1:
The synchronous rectification controller dynamically adjusts its operation based on the detected primary-side controller mode. During burst mode, the controller suspends switching of the synchronous rectification transistor and operates the secondary-side circuit as a diode rectifier. During non-burst mode, it resumes synchronous rectification switching. This dynamic adaptation resolves the contradiction by optimizing energy loss while maintaining rectification functionality through mode-dependent operation.
Solution Approach 2:
The invention changes the operational parameters of the synchronous rectification transistor based on the detected operation mode. In burst mode, the switching frequency and duty cycle are effectively reduced to zero, transitioning to diode rectification. In non-burst mode, normal synchronous rectification parameters are restored. This parameter change strategy minimizes switching losses during light load conditions while preserving rectification performance.
2Loss of energy
If synchronous rectification controller operates continuously, then rectification control is maintained, but power consumption increases
Solution Approach 1:
The synchronous rectification controller operates periodically based on the operation mode of the primary-side controller. During burst mode, the controller enters a low-power state with suspended switching activity. During non-burst mode, it resumes periodic switching control. This periodic operation pattern significantly reduces average power consumption while maintaining rectification control capability when needed.
Solution Approach 2:
The synchronous rectification controller autonomously detects the operation mode of the primary-side controller and automatically adjusts its own operation accordingly. The automatic shutdown circuit monitors the operation mode and independently controls the suspension or resumption of switching without external intervention. This self-service mechanism reduces power consumption while preserving rectification control through autonomous adaptation.
3Loss of energy
If automatic shutdown circuit is added to detect operation mode, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The automatic shutdown circuit is integrated into the existing synchronous rectification controller, which already performs rectification control functions. The same controller hardware is utilized to detect operation mode and manage both rectification control and shutdown functionality. This multi-functionality approach reduces power consumption through automatic shutdown while minimizing the increase in device complexity by reusing existing circuit resources.
Solution Approach 2:
The invention merges the automatic shutdown circuit functionality with the synchronous rectification controller into a single integrated unit. The detection of operation mode and the control of shutdown are combined within the existing controller architecture. This merging strategy achieves power reduction through automatic shutdown while avoiding the complexity increase that would result from completely separate circuits.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution significantly reduces power consumption by minimizing switching losses and operating current, achieving further efficiency in AC/DC conversion, especially during light load or standby states without the need for additional circuit components to monitor operation modes.
Implementation Method 1
a photocoupler 204
Implementation Method 2
a transformer T1, a diode D1, an output capacitor C1, a switching transistor M1, and a synchronous rectification transistor M2
Data Source
AI summary
A synchronous rectification controller is arranged on the secondary side of an insulated synchronous rectification DC/DC converter. The synchronous rectification controller controls a synchronous rectification transistor M. An automatic shutdown circuit judges, based on the voltage VDS across the synchronous rectification transistor, whether the operation mode of a primary-side controller is a burst mode or a non-burst mode. When judgment has been made that the operation mode is the burst mode, the automatic shutdown circuit instructs a driver to suspend the switching of the synchronous rectification transistor M.