Switching Regulator Overcurrent Protection Circuit
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Solution Overview
Problem
Conventional switching regulator circuits provide incomplete overcurrent protection, especially when a short-circuit occurs, and are insufficient in cases of long switching cycles, leading to delayed protection due to the reliance on a soft start function and counter-based detection mechanisms.
Innovation Solution
A switching regulator circuit with a load switch that remains off upon detection of overcurrent, utilizing a combination of overcurrent detection comparators, timer circuits, and logic circuits to ensure complete protection without relying on a soft start function, allowing for effective protection regardless of switching cycle settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a counter-based detection mechanism is used to detect overcurrent, then the circuit can detect overcurrent conditions, but the protection is delayed when switching cycles are long
Solution Approach 1:
The patent transitions from a static counter-based detection mechanism to a dynamic timer-based mechanism that continuously monitors overcurrent conditions. The timer circuit can be reset during each switching cycle, allowing the protection response time to adapt dynamically to different switching frequencies while maintaining reliable protection.
2Reliability
If a soft start function is used to stop the circuit during overcurrent, then the switching transistor is protected, but the protection is incomplete when short-circuit occurs
Solution Approach 1:
The patent segments the protection function into two independent parts: the soft start circuit that stops PWM generation, and a separate load switch control mechanism that disconnects the load. This segmentation allows each part to perform its specific protection function, with the load switch providing additional protection against short-circuit conditions that the soft start alone cannot handle.
Solution Approach 2:
The load switch acts as an intermediary component between the overcurrent detection circuit and the power delivery path. When overcurrent is detected, the load switch opens to disconnect the load, preventing harmful current from reaching the switching transistor and other circuit components, thereby providing complete protection against short-circuit conditions.
3Reliability
If the load switch is kept off during overcurrent, then complete protection is achieved, but the circuit complexity increases
Solution Approach 1:
The patent merges the load switch control function with the existing overcurrent detection and soft start circuits. The timer circuit that generates the stop signal for the soft start function is also used to control the load switch, combining multiple protection functions into a unified control mechanism rather than adding completely separate control circuits.
Solution Approach 2:
The timer circuit serves multiple functions: it detects overcurrent conditions, generates stop signals for the soft start function, and controls the load switch. This multi-functionality reduces the need for separate dedicated circuits for each protection function, thereby limiting the increase in overall circuit complexity while achieving complete protection.
Data Source
AI summary
One embodiment provides a switching regulator circuit having an overcurrent protection function that enables complete overcurrent protection though simple in configuration. The switching regulator circuit generates an output signal while boosting an input voltage by switching on/off a switching element using a PWM signal. The switching regulator circuit is equipped with a load switch which is connected to the switching element in series and is normally on. And, the switching regulator circuit is further equipped with an overcurrent protection circuit which keeps the load switch off if a current flowing through the switching element is an overcurrent.