MOSFET Fault Protector for Laser Diode ESD Protection

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Solution Overview

Problem

Opto-electronic devices, such as laser diodes, are vulnerable to electrical-induced damage from electrostatic discharge (ESD) and power surges during power-up and power-down sequences, which existing protection methods fail to adequately address due to insufficient impedance and reactive capabilities.

Innovation Solution

A fault protector comprising a MOSFET with an integral body-diode and additional passive components, such as a capacitor and resistor, is connected directly across the laser diode to proactively manage voltage and current during ESD events and power-related faults, ensuring the voltage does not exceed the device's maximum ratings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing protection methods are used, then some ESD protection is provided, but the impedance is insufficient and reactive capabilities are inadequate

Engineering Contradiction:

ImproveESD protection effectivenessVSAvoidvoltage surge damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The fault protector proactively monitors voltage and current parameters before damage occurs. During power-up and power-down sequences, it detects potential over-voltage or over-current conditions and takes preventive action by conducting excessive current away from the opto-electronic device, preventing cumulative fatigue damage before it leads to failure.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The fault protector acts as an intermediary protective device between the power supply and the opto-electronic device. It includes a MOSFET with integral body-diode that provides a controlled path for ESD current, and a capacitor that couples to the gate to enhance reactive capabilities during ESD events, thereby mediating the harmful effects of voltage surges.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If proactive ESD protection is implemented, then device damage is prevented, but circuit complexity increases

Engineering Contradiction:

Improvedevice protectionVSAvoidprotection circuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The fault protector merges multiple protective functions into a single integrated circuit. The MOSFET with its integral body-diode combines two protective elements (MOSFET and diode) into one component, and the overall circuit integrates voltage monitoring, current limiting, and ESD protection functions that would otherwise require separate components, thereby reducing overall circuit complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The fault protector is designed to provide multiple protective functions simultaneously: it protects against positive ESD events, negative ESD events, and power surge conditions during power-up and power-down sequences. This multi-functional approach eliminates the need for separate protection circuits for different failure modes, simplifying the overall protection architecture.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 damage from both positive and negative ESD events and power surges by conducting excessive current away from the laser diode, maintaining the device's operational integrity without adding significant resistance or capacitance, thus simplifying laser diode driving and extending the device's lifespan.

Implementation Method 1

protecting laser diodes from damage caused by ESD... When an ESD discharge occurs, the discharge voltage can range anywhere between 4000 and up to as much as 32,000 volts DC

Methodology Applied

Scientific EffectElectrostatic Discharge: Electrostatic Discharge

Implementation Method 2

A capacitor may be coupled between a drain and a gate of the MOSFET... the capacitor provides reactive capability

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 3

The drain of the MOSFET is connectable to a first terminal of an opto-electronic device, and the source of the MOSFET is connectable to a second terminal... conducting excessive current away from the laser diode

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentUS8902557B2Fault protector for opto-electronic devices and associated methods

Publication Date: 2014.12.02 PANGOLIN LASER SYSTEMS LLC

AI summary

A fault protector for an opto-electronic device includes a MOSFET having an integral body-diode. A capacitor is connected between a drain and a gate of the MOSFET, and a resistor is connected between the gate and a source of the MOSFET. The drain of the MOSFET is connectable to a first terminal of an opto-electronic device, and the source of the MOSFET is connectable to a second terminal of the opto-electronic device. The device overcomes problems of previously known techniques by preventing a reverse-bias voltage from exceeding an absolute maximum specified by a manufacturer, and also prevents ESD or other power-related faults from exceeding the maximum forward-bias voltage of the laser diode, while not adding significant resistance or capacitance to the laser diode, thereby not complicating the task of driving the laser diode.