Latch-up Resistant ESD Protection Circuit with Self-Resetting Sensing Unit
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Solution Overview
Problem
Conventional ESD protection circuits risk latch-up due to the continuous activation of sustaining units during normal operations, such as power bounces or signal noise, leading to significant current draw from the power source.
Innovation Solution
An ESD protection circuit with a sensing unit that activates the clamping and sustaining units during ESD events and self-resets after a period, deactivating the sustaining unit to prevent latch-up, thereby ensuring the circuit deactivates and prevents continuous current draw.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sustaining unit is added to improve the discharging ability of the clamping circuit, then the ESD protection capability is enhanced, but the risk of latch-up increases during normal operation
Solution Approach 1:
The sensing unit dynamically controls the activation and deactivation of the sustaining unit based on real-time detection of ESD events. The circuit transitions from a static configuration to a dynamic one where the sustaining unit is only active when needed, preventing latch-up during normal operation while maintaining ESD protection capability.
Solution Approach 2:
The sensing unit provides feedback control by detecting voltage changes and controlling the activation of the sustaining unit. This feedback mechanism ensures the sustaining unit is activated only during actual ESD events and deactivated during normal operation, resolving the contradiction between protection capability and latch-up risk.
2Reliability
If the sustaining unit remains continuously activated to maintain strong discharging ability, then ESD protection is improved, but current consumption increases significantly during normal operation
Solution Approach 1:
The sensing unit enables periodic or event-driven activation of the sustaining unit rather than continuous operation. The circuit activates the sustaining unit only during ESD events and deactivates it during normal operation, reducing current consumption while maintaining discharging ability when needed.
Solution Approach 2:
The sensing unit automatically detects ESD events and controls the activation of the sustaining unit without external intervention. The circuit serves itself by monitoring its own state and activating protection only when necessary, eliminating the need for continuous current draw.
3Reliability
If the detecting unit is enlarged to improve ESD detection capability, then the protection response is enhanced, but the circuit area increases
Solution Approach 1:
The sensing unit serves multiple functions: detecting ESD events, controlling the sustaining unit activation, and providing feedback control. This multi-functionality consolidates what would otherwise require separate circuits into a single compact unit, improving detection capability without proportionally increasing area.
Solution Approach 2:
The patent combines the detecting unit and sustaining unit control functions into an integrated sensing unit. By merging these functions, the circuit achieves enhanced ESD detection and control capabilities while minimizing the overall circuit area through functional integration.
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
The solution effectively prevents latch-up by self-deactivating the sustaining unit after an ESD event, reducing unnecessary current consumption and maintaining normal operation during non-ESD conditions.
Implementation Method 1
the voltage level V1 between said ESD amplifying unit 14 and said detecting unit 12 instantly jumps to the same level as Vdd, causing said draining unit 16 to be activated and said power node Vdd to discharge through said draining unit 16
Implementation Method 2
Said sustaining unit 18 improves the discharging ability of said clamping circuit described below. When node V1 is attacked by an ESD zap and its voltage level is increased to the same as the power source Vdd, the voltage at the internal node V2 of said amplifying unit 14 is pulled to ground level, activating said sustaining unit 18 to form a closed current path from the power source Vdd to V1. At this moment, the current driving ability of said sustaining unit 18 on said node V1 is stronger than the discharging ability of said ESD detecting unit 12 on V1. As a result, the voltage level at V1 is maintained at the same level as said power source Vdd. By means of this positive feedback
Data Source
AI summary
The present invention is to provide a latch-up resistant electrostatic discharge (ESD) protection circuit and method thereof, which comprises a clamping circuit being able to discharge when activated, a sustaining unit for directing electrostatic charge via said sustaining unit to said clamping circuit when activated and a sensing unit for activating said clamping circuit and said sustaining unit. When an ESD event, a signal noise or a power bounce is detected, said clamping circuit and said sensing unit is activated, said sustaining unit is activated to increase discharging ability of said clamping circuit, and then said sensing unit self resets after a period of time to deactivate said sustaining unit, thereby said clamping circuit is deactivated and a latch-up is prevented.