Isolator Circuit Voltage Regulator Transient Immunity

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Solution Overview

Problem

Traditional opto-isolators are susceptible to common mode input transients and have inefficient switching characteristics due to their dependence on current strength, leading to reduced efficiency and susceptibility to electrostatic discharge.

Innovation Solution

A regulator circuit generates a voltage from an input current to power functional circuitry, which generates a signal indicative of the input current, and this signal is transmitted across an isolation barrier using a transformer, providing immunity to common mode transients and electrostatic discharge while maintaining efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If external resistor is used to overdrive the LED to maintain output high state during common mode transient, then immunity to common mode transients is improved, but operating efficiency deteriorates due to power dissipation through the resistor

Engineering Contradiction:

Improveimmunity to common mode transientsVSAvoidpower dissipation

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent removes the external resistor from the circuit by integrating a current source directly within the opto-isolator device. This eliminates the continuous power dissipation associated with the external resistor while maintaining the ability to drive the LED during common mode transients through the integrated current source that activates only when needed.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The opto-isolator becomes self-sufficient by incorporating an internal current source that automatically activates to maintain LED operation during common mode transients. This eliminates the need for external components and continuous power dissipation, as the current source only operates when transient protection is required.

Inventive Principle:

Principle #25Self-service

2Strength

If current strength is increased to improve signal transmission, then signal strength is improved, but switching characteristics deteriorate due to dependence on current strength

Engineering Contradiction:

Improvesignal strengthVSAvoidswitching characteristics

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The patent changes the operating parameters of the LED by using a regulated voltage source instead of direct current driving. This allows the LED to operate at optimized current levels for both signal strength and switching performance, decoupling the relationship between input current and output signal strength through the regulation mechanism.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a voltage regulator as an intermediary between the input current source and the LED. This regulator mediates the relationship by converting variable current inputs into a stable voltage that drives the LED, thereby improving switching characteristics while maintaining adequate signal strength through controlled current delivery.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If traditional opto-isolator design is used, then simplicity is maintained, but susceptibility to electrostatic discharge increases

Engineering Contradiction:

Improvecircuit simplicityVSAvoidelectrostatic discharge susceptibility

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent incorporates ESD protection circuits and clamping diodes that are activated before electrostatic discharge events can damage sensitive components. These protective elements are built into the device structure to provide immediate protection during transient events while maintaining the overall simplicity of the opto-isolator design.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent combines multiple functional elements (opto-coupling components, current source, voltage regulator, and ESD protection circuits) into a single integrated device structure. This composite approach provides comprehensive protection against electrostatic discharge while maintaining device simplicity through integration, eliminating the need for separate external protection components.

Inventive Principle:

Principle #40Composite materials

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 achieves improved isolation with reduced susceptibility to common mode transients and increased efficiency by decoupling the output from current strength, enabling faster signal transfer and lower power consumption.

Implementation Method 1

the transmitter circuit, when supplied with the voltage, is responsive to supply the signal into a primary winding of the transformer to cause energy to be coupled into a secondary winding of the transformer, the isolation barrier being disposed between the primary and secondary windings

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS8861229B2Isolator circuit including a voltage regulator

Publication Date: 2014.10.14 SKYWORKS SOLUTIONS INC

AI summary

An apparatus includes a regulator circuit that generates a voltage in response to an input current being supplied to an input terminal and functional circuitry, powered by the voltage generated by the regulator circuit. The functional circuitry, e.g., an oscillator, generates a signal using the generated voltage, the signal indicative that the current is being supplied to the apparatus. The signal can be provided over an isolation link to provide a control signal for controlling a high voltage driver circuit.