DC-DC Converter Backflow Suppression Control
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Solution Overview
Problem
Existing DC-DC converters experience increased consumption current due to unnecessary switch control of the rectification transistor, especially at low loads where current backflow is likely, leading to inefficiencies and higher power consumption.
Innovation Solution
A DC-DC converter configuration that includes a power supply control circuit generating pulse signals, switching elements, an inductor, and comparison circuits to suppress switch control by turning off the rectification transistor when current backflow is detected and maintaining it off during subsequent cycles if backflow detection occurs early or at the same timing as a reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the synchronous rectification transistor is controlled to turn on and off based on current direction detection, then the power supply can handle current backflow situations, but the consumption current increases due to unnecessary switch control at low loads
Solution Approach 1:
The patent applies preliminary action by detecting current backflow in advance and turning off the synchronous rectification transistor before the backflow occurs. The control circuit monitors the current direction through the transistor and proactively disables it when backflow is detected, preventing the harmful current flow without requiring reactive switching. This resolves the contradiction by maintaining reliability through early detection and prevention while avoiding the energy waste of continuous or unnecessary switching operations at low loads.
2Reliability
If the synchronous rectification transistor is continuously controlled to maintain proper current direction, then current backflow is prevented, but the device complexity and control overhead increase
Solution Approach 1:
The patent implements self-service by utilizing the inherent characteristics of the synchronous rectification transistor and the natural current flow behavior in the circuit. The control circuit leverages the transistor's own current conduction properties and the circuit's natural operating states to determine when switching is necessary. This approach maintains reliable current direction control while minimizing control circuit complexity by avoiding overly sophisticated control mechanisms and focusing on essential switching operations based on actual circuit conditions.
3Reliability
If switch control is applied to handle all current flow scenarios, then all current conditions are managed, but power efficiency decreases at low loads due to unnecessary switching
Solution Approach 1:
The patent applies partial action by implementing selective switch control that activates only when current backflow is actually detected or anticipated. Instead of continuously controlling the synchronous rectification transistor in all operating conditions, the control circuit applies switching action only in the specific scenario where backflow occurs or is about to occur. This resolves the contradiction by maintaining sufficient current flow management reliability while significantly reducing energy losses from unnecessary switching operations during normal low-load operation.
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 configuration effectively reduces consumption current by minimizing unnecessary switch control of the rectification transistor, particularly at low loads, thereby enhancing power efficiency.
Implementation Method 1
by energy stored in the inductor L201, a current flows in the capacitor C201 through the synchronous rectification transistor MN201 and the inductor L201
Data Source
AI summary
A DC-DC converter according to the present invention includes a power supply control circuit—that generates pulse signals, an output transistor that is controlled to be turned on and off based on the pulse signal, a rectification transistor—that is controlled to be turned on and of based on a control signal, a coil provided between a node between the output transistor and the rectification transistor, and an external output terminal, a comparator that compares a voltage of the node—with a reference voltage, a first control circuit that generates a control signal based on a comparison result of the comparator, and a second control circuit that generates the control signal based on a backward-current detection timing and a reference timing.