Switching Regulator ON-Timer Clamp for Reliable Overvoltage Protection
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Solution Overview
Problem
Existing DC/DC converters with overvoltage protection circuits incorrectly detect overvoltage when external elements fail or are disconnected from the output terminal, leading to unreliable protection.
Innovation Solution
A switching regulator control circuit incorporating a comparator, RS-FF circuit, ON-timer circuit with current source, ripple generation, averaging, and clamp circuits to provide overvoltage protection independently of external elements, using a voltage divider and NMOS transistors to manage output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overvoltage protection is implemented using external elements connected to the output terminal, then overvoltage detection can be achieved, but the detection becomes unreliable when external elements fail or are disconnected
Solution Approach 1:
The invention extracts the overvoltage detection function from external elements and relocates it to the ON-timer circuit within the control IC. By moving the detection mechanism inside the protected system, the detection becomes independent of external elements that may fail or be disconnected, thereby improving reliability
Solution Approach 2:
The invention introduces an intermediary mechanism (the ON-timer circuit with clamp circuit) that mediates between the power supply voltage and the output voltage monitoring. This intermediary uses the power supply voltage as a reference to indirectly monitor output voltage status, avoiding direct dependence on external detection elements
2Reliability
If overvoltage protection circuit is added to the DC/DC converter, then overvoltage protection capability is improved, but the device complexity increases
Solution Approach 1:
The invention merges the overvoltage protection function with the existing ON-timer circuit in the switching regulator control IC. By combining multiple functions (timing control and overvoltage protection) into a single circuit block, the patent avoids adding separate protection circuits, thereby minimizing increased complexity while improving protection capability
Solution Approach 2:
The ON-timer circuit is designed to serve multiple functions: normal timing control during regular operation and overvoltage detection/protection when abnormal conditions occur. This multi-functionality eliminates the need for dedicated protection hardware, reducing overall device complexity
Data Source
AI summary
Provided is a DC/DC converter capable of providing overvoltage protection reliably without being affected by, for example, an external element connected to an output terminal. The DC/DC converter includes a comparator, an RS-FF circuit, a drive circuit, and an ON-timer circuit, and the ON-timer circuit includes: a current source circuit which provides an electric current based on a power supply voltage; a ripple generation circuit which generates a ripple voltage; an averaging circuit which averages the ripple voltage; a timer circuit which generates an ON-timer signal; and an overvoltage protection circuit (clamp circuit).