TJBS-PT Diode Temperature-Compensated Breakdown Voltage

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Solution Overview

Problem

High-efficiency rectification in AC automotive generators is hindered by forward power losses and temperature-dependent breakdown voltages in traditional pn diodes, leading to inefficiencies and potential voltage overshooting during load changes.

Innovation Solution

A trench junction barrier Schottky-punch through diode (TJBS-PT) with a low temperature coefficient breakdown voltage, utilizing a punch-through effect instead of avalanche breakdown, resulting in reduced forward voltage and reverse currents, and packaged in a press-fit diode housing for efficient rectification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional pn diodes are used for rectification, then breakdown voltage limits generator voltage during load dumps, but forward power losses increase and efficiency decreases

Engineering Contradiction:

Improvevoltage limiting capabilityVSAvoidforward power losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the fundamental operating parameters of the diode by transitioning from pn junction avalanche breakdown to Schottky barrier breakdown mechanism. This parameter change enables simultaneous achievement of low forward voltage drop (reducing power losses) and adequate breakdown voltage (maintaining voltage limiting capability), thereby resolving the contradiction between efficiency and reliability.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If pn diodes operate in avalanche breakdown to limit voltage, then breakdown voltage provides protection, but temperature increase causes breakdown voltage to rise and voltage limiting becomes less effective

Engineering Contradiction:

Improvevoltage protectionVSAvoidbreakdown voltage temperature coefficient

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent changes the breakdown mechanism from avalanche breakdown (with positive temperature coefficient) to Schottky barrier breakdown (with negative or near-zero temperature coefficient). This parameter change ensures that breakdown voltage remains stable or decreases with temperature increase, maintaining effective voltage limiting capability under thermal stress and resolving the contradiction between protection reliability and temperature sensitivity.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If Schottky diodes are used to reduce forward power losses, then efficiency increases, but breakdown voltage becomes insufficient to limit generator voltage during load dumps

Engineering Contradiction:

Improveforward power lossesVSAvoidvoltage limiting capability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent optimizes the Schottky barrier diode parameters including barrier height, doping concentration, and junction geometry to achieve both low forward voltage drop and sufficient breakdown voltage. By carefully adjusting these parameters, the diode simultaneously delivers high efficiency (low power losses) and adequate voltage limiting capability during load dumps, resolving the contradiction between energy efficiency and voltage protection.

Inventive Principle:

Principle #35Parameter changes

4Temperature

If cooling measures are implemented to dissipate heat from pn diodes, then temperature control improves, but device complexity and cost increase

Engineering Contradiction:

Improvediode temperature controlVSAvoidcooling system complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent converts the harmful effect of heat generation into a beneficial outcome by using the heat to activate the breakdown mechanism that limits voltage. The Schottky barrier breakdown occurs at lower voltages and generates less heat than avalanche breakdown, reducing the need for complex cooling systems while maintaining protective functionality, thereby resolving the contradiction between temperature control and device complexity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 TJBS-PT diode significantly reduces maximum voltage occurrences in vehicle electrical systems during malfunctions, minimizing heat generation and power losses, and maintaining efficiency across varying temperatures.

Implementation Method 1

High-efficiency Schottky diodes are diodes having a low forward voltage and a reverse current almost independent of the reverse voltage

Methodology Applied

Scientific EffectSchottky barrier effect:

Implementation Method 2

The pn structures are operated in avalanche breakdown. The power drop at the diode corresponds to the product of the reverse voltage of the diode and the generator current

Methodology Applied

Scientific EffectAvalanche breakdown: Avalanche Breakdown

Implementation Method 3

A trench junction barrier Schottky-punch through diode (TJBS-PT) with a low temperature coefficient breakdown voltage, utilizing a punch-through effect instead of avalanche breakdown

Methodology Applied

Scientific EffectPunch-through effect:

Data Source

PatentUS9142552B2Semiconductor array having temperature-compensated breakdown voltage

Publication Date: 2015.09.22 ROBERT BOSCH GMBH

AI summary

A semiconductor array is described whose breakdown voltage has only a very low temperature coefficient or none at all and therefore there is little or no temperature-dependent voltage rise. The voltage limitation is achieved by a punch-through effect.