ESD Protection Circuit for Switching Power Converter
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Solution Overview
Problem
Existing ESD protection circuits for switching power converters, particularly those with large n-channel MOSFETs, face challenges in providing reliable protection due to unstable oscillatory behavior and false triggering, especially when using direct sensing and coupling methods, which can lead to damage from electro-static discharge (ESD) events and shoot-through conditions.
Innovation Solution
An ESD protection circuit employing an ESD sense node separate from the switching node, using a current conduction path and an ESD sensing circuit to generate a trigger signal that keeps the high-side switching element off and turns on the low-side switching element during ESD events, thereby providing a conductive discharge path while avoiding conflicts with normal operation signals through logic gates and indirect sensing and coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If direct sensing method is used to detect ESD events on the switching node, then ESD detection speed is improved, but false triggering during normal operation increases
Solution Approach 1:
The patent segments the sensing function by introducing a dedicated ESD sense node separate from the switching node. The ESD sensing circuit monitors voltage changes on this isolated sense node rather than directly on the switching node, allowing ESD detection while filtering out normal switching spikes that would cause false triggering.
Solution Approach 2:
The patent introduces an intermediary current conduction path (through the body diode of the high-side switching element or a dedicated diode) that couples ESD events from the switching node to the ESD sense node. This intermediary path allows ESD detection indirectly, filtering out fast switching transients while maintaining ESD event detection capability.
2Speed
If direct coupling method is used to apply ESD trigger signal to the gate of the low-side switching element, then ESD protection response time is improved, but signal conflict with normal operation control signal increases
Solution Approach 1:
The patent introduces logic gates as intermediary components between the ESD sensing circuit and the gate driver of the low-side switching element. These logic gates process the ESD trigger signal and combine it with the normal control signal, ensuring that ESD protection is activated without conflicting with normal switching operations. The logic gate acts as a mediator that resolves signal conflicts while maintaining fast response.
3Reliability
If the low-side switching element is forced to turn on during ESD event, then ESD discharge path is provided, but shoot-through condition with high-side switching element may occur
Solution Approach 1:
The patent employs logic gates that receive feedback about the state of both the high-side and low-side switching elements. The logic gate controlling the low-side element only activates it when the high-side element is confirmed to be off, providing feedback-based control that prevents shoot-through conditions while maintaining effective ESD protection.
Solution Approach 2:
The patent uses logic gates to preliminarily prevent shoot-through by checking the state of the high-side switching element before allowing the low-side element to turn on during an ESD event. This preliminary anti-action ensures that protective measures are taken to prevent the harmful shoot-through condition before it can occur.
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 ensures reliable ESD protection by preventing shoot-through conditions, maintaining stable operation during ESD events, and reducing false triggering, thus protecting the switching elements from damage and ensuring continuous power supply.
Implementation Method 1
All electronic circuits are susceptible to electro-static discharge (ESD) which can damage the circuit's components
Implementation Method 2
a current conduction path which couples an ESD event that occurs on the switching node to the ESD sense node
Data Source
AI summary
An ESD protection circuit for a switching power converter which includes a high-side switching element connected between a supply voltage and the switching node, and a low-side switching element connected between the switching node and a common node. A current conduction path couples an ESD event that occurs on the switching node to an ESD sense node, and an ESD sensing circuit coupled to the sense node generates a trigger signal when an ESD event is sensed. A first logic gate keeps the high-side switching element off when the trigger signal indicates the sensing of an ESD event, and a second logic gate causes the low-side switching element to turn on when an ESD event is sensed such that the low-side switching element provides a conductive discharge path between the switching node and common node.