Open Drain DMOS Driver with Integrated ESD Protection

Solution Overview

Problem

Integrated circuit devices, particularly those interfacing with LIN and CAN buses in automotive electronics, face challenges in achieving high electrostatic discharge (ESD) robustness and electromagnetic interference (EMI) immunity while requiring compact and cost-effective solutions for ESD protection, as existing solutions often result in large layout areas and increased fabrication costs due to the need for series reverse blocking diodes.

Innovation Solution

The integration of an open drain output driver cell with ESD protection, featuring a central drain double-diffused metal-oxide-semiconductor (DMOS) transistor structure that incorporates a reverse blocking diode within the drain, eliminating the need for separate metal routing and merging the drift region with the driver, thereby achieving self-protected and compact ESD and reverse voltage protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If series reverse blocking diodes are added for ESD protection, then ESD robustness is improved, but layout area and fabrication cost increase

Engineering Contradiction:

ImproveESD robustnessVSAvoidlayout area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the reverse blocking diode function with the output driver cell by integrating the diode structure within the drain region of the driver transistor. This combination eliminates the need for separate discrete diode components and their associated metal routing, thereby reducing layout area while maintaining ESD protection capability. The merged structure allows the same physical region to serve both driving and reverse blocking functions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The output driver cell is designed to perform multiple functions simultaneously: it provides the primary driving function for the LIN/CAN bus interface while also incorporating intrinsic ESD protection and reverse voltage blocking capabilities. The drift region and junction structures are configured to serve both normal operation and protection functions, making the driver cell a universal component that eliminates the need for separate protection devices.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If series reverse blocking diodes are added for ESD protection, then ESD robustness is improved, but fabrication cost increases

Engineering Contradiction:

ImproveESD robustnessVSAvoidfabrication cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the reverse blocking diode function with the output driver cell by integrating the diode structure within the drain region of the driver transistor. This combination eliminates the need for separate discrete diode components and their associated metal routing, thereby reducing layout area while maintaining ESD protection capability. The merged structure allows the same physical region to serve both driving and reverse blocking functions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The output driver cell is designed to perform multiple functions simultaneously: it provides the primary driving function for the LIN/CAN bus interface while also incorporating intrinsic ESD protection and reverse voltage blocking capabilities. The drift region and junction structures are configured to serve both normal operation and protection functions, making the driver cell a universal component that eliminates the need for separate protection devices.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If separate ESD protection structures are used, then ESD protection is provided, but device complexity increases

Engineering Contradiction:

ImproveESD protectionVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the reverse blocking diode function with the output driver cell by integrating the diode structure within the drain region of the driver transistor. This combination eliminates the need for separate discrete diode components and their associated metal routing, thereby reducing layout area while maintaining ESD protection capability. The merged structure allows the same physical region to serve both driving and reverse blocking functions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The output driver cell is designed to be self-protecting through intrinsic ESD protection mechanisms built into its structure. The drift region and junction configurations automatically provide ESD clamping and reverse voltage blocking without requiring external protection components or additional control circuitry. The driver cell serves itself by incorporating protection functions that activate automatically during ESD events.

Inventive Principle:

Principle #25Self-service

Data Source

PatentEP2951865B1Semiconductor device with ESD self-protection and LIN bus driver comprising the same

Publication Date: 2020.03.25 MICROCHIP TECHNOLOGY INC

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Figure 2A

AI summary

A double-diffused metal oxide semiconductor (DMOS) dual structure is configured as an open drain output driver having electrostatic discharge (ESD) protection without requiring metal connections for the ESD and reverse voltage blocking diode protections. One of a pair of source cells (102b, 104b, 106b) is used as an open drain output cell, forming eg. a reverse blocking diode (234) and achieving bipolar operation in the on-state, a built-in structure, eg. a built-in SCR, being used for ESD self-protection. The gate electrode (110b) adjacent the reverse blocking diode is connected to the open drain output terminal (232).