ESD Protection Circuit Preventing Latch-Up via Control Logic

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Solution Overview

Problem

Conventional ESD protection circuits are prone to latch-up, which creates an undesirable current path between rails, leading to circuit malfunction and potential irreversible damage to integrated circuits.

Innovation Solution

An ESD module with a control circuit that couples between first and second rails and an ESD circuit, allowing a current path only during ESD events to dissipate ESD current, and preventing latch-up by ensuring no current path when no ESD event is sensed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ESD protection circuits are used to dissipate ESD current, then ESD protection capability is improved, but latch-up occurs creating undesirable current paths between rails

Engineering Contradiction:

ImproveESD protection capabilityVSAvoidlatch-up current path

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A control circuit is introduced as an intermediary between the ESD event and the ESD protection circuit. This control circuit monitors for ESD events and only activates the ESD protection circuit when needed, preventing direct activation that would cause latch-up. The intermediary control mechanism resolves the contradiction by enabling ESD protection only under controlled conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The ESD protection circuit transitions from a static always-on configuration to a dynamic controlled configuration. The circuit is activated only when the control circuit detects an ESD event, and deactivated otherwise. This dynamic behavior allows the system to provide ESD protection when needed while avoiding latch-up during normal operation.

Inventive Principle:

Principle #15Dynamics

2Loss of energy

If a current path is created between rails to dissipate ESD current, then ESD current dissipation is improved, but circuit malfunction or irreversible damage may occur due to latch-up

Engineering Contradiction:

ImproveESD current dissipationVSAvoidcircuit functionality

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The control circuit performs preliminary detection of ESD events before activating the ESD protection circuit. By sensing the ESD event first and then selectively activating protection, the system ensures that current paths are created only when necessary for ESD dissipation, preventing premature activation that would cause circuit malfunction or damage.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If ESD protection circuit is always active to protect against ESD events, then ESD protection is improved, but power consumption increases and latch-up risk increases

Engineering Contradiction:

ImproveESD protectionVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The ESD protection circuit operates periodically rather than continuously. The control circuit continuously monitors for ESD events and activates the protection circuit only during detected ESD events. This periodic activation maintains ESD protection capability while significantly reducing power consumption compared to always-on operation.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS8879221B2ESD protection without latch-up

Publication Date: 2014.11.04 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A device having an ESD module is disclosed. The ESD module includes an ESD circuit coupled between first and second rails and a control circuit coupled between the rails and to the ESD circuit. When the control circuit senses an ESD event, it causes the ESD circuit to create a current path between the rails to dissipate ESD current. When no ESD event is sensed, the control circuit ensures that no current path is created between the rails to prevent latch-up.