Switching Regulator Output Control for High-Side Short Overcurrent
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional switching regulators with output control circuits fail to suppress overcurrents when the output terminal of a synchronous rectification type switching regulator operating in PWM fixed mode is short-circuited with a high-side node.
Innovation Solution
An output control circuit and switching regulator that includes a backflow detection circuit and a control circuit to detect backflow currents and forcibly turn off high-side and low-side transistors when an error voltage falls below a reference voltage, thereby suppressing overcurrents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional overcurrent protection function is used in switching regulator, then ground fault protection is achieved, but overcurrent cannot be suppressed when output terminal is short-circuited with high-side node
Solution Approach 1:
The patent introduces a backflow detection circuit as an intermediary component that specifically detects backflow current through the low-side transistor. This intermediary detection mechanism enables the control circuit to identify high-side node short-circuit conditions that conventional protection circuits cannot detect, thereby expanding protection coverage while maintaining reliable overcurrent suppression.
Solution Approach 2:
The protection function is segmented into two independent detection mechanisms: conventional overcurrent protection for ground faults and backflow detection for high-side node short circuits. This segmentation allows each protection mechanism to specialize in detecting specific fault types, achieving comprehensive protection coverage without compromising the reliability of either protection function.
2Reliability
If backflow detection circuit is added to detect backflow current, then overcurrent suppression in high-side node short circuit is achieved, but device complexity increases
Solution Approach 1:
The backflow detection circuit is designed to perform multiple functions: detecting backflow current through the low-side transistor, identifying high-side node short-circuit conditions, and providing control signals for overcurrent suppression. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby limiting the increase in device complexity while achieving reliable overcurrent suppression.
Solution Approach 2:
The backflow detection function is merged with the existing control circuit architecture. The backflow detection circuit shares the control circuit's processing resources and integrates with the existing transistor control mechanism, allowing the new protection function to be added without requiring completely separate independent circuits, thus controlling the increase in overall device complexity.
Data Source
AI summary
An output control circuit includes a detection circuit and a control circuit. The detection circuit contains an input port connected to a connection point and an output port which detects a current flowing toward the connection point through an inductor with one end connected to the connection point and outputs a detection signal. The control circuit controls an on or off state of a high-side transistor and a low-side transistor in the case of a signal level of a received signal indicating that an error voltage, which is amplified from a difference between a first reference voltage and a feedback voltage proportional to an output voltage, falls below a second reference voltage, and that the current is detected.