Power Switch Turn-Off Control with Bias-Triggered Gate Discharge

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Solution Overview

Problem

Conventional power switches are prone to damage due to excessive bias voltage when turning off, leading to potential burnout under long-term operation.

Innovation Solution

A control device comprising a voltage boost circuit, a discharge circuit, and a bias voltage generating circuit that compares output and control voltages to manage the discharge path, reducing the voltage difference and preventing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the power switch is turned off by applying low control voltage to the gate, then the transistor can be turned off smoothly, but the source and gate are subjected to excessively high bias voltage that may damage the power switch

Engineering Contradiction:

Improvesmooth turn-off operationVSAvoidexcessive bias voltage damage

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The discharge circuit is activated in advance before the power switch is completely turned off. The control device detects when the power switch is in the off state and immediately activates the discharge circuit to discharge the control end voltage, preventing the accumulation of excessive bias voltage that would otherwise damage the transistor during subsequent operations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A discharge circuit is introduced as an intermediary component between the control end and ground. This discharge circuit, controlled by a control device that monitors the power switch state, provides a controlled discharge path that mediates the voltage difference, allowing the control end to be safely discharged without directly exposing the transistor to harmful voltage spikes

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the control end voltage is not discharged when the power switch is off, then the circuit operation is simple, but the voltage difference between control end and output end becomes excessive causing potential damage

Engineering Contradiction:

Improvecircuit operation simplicityVSAvoidpower switch durability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The control device automatically monitors the power switch state and activates the discharge circuit when needed, without requiring external intervention. The system self-regulates by detecting when the power switch is off and autonomously discharging the control end voltage, maintaining reliability while keeping the operational interface simple

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The control device continuously monitors the state of the power switch and uses this feedback information to control the discharge circuit. When the power switch is detected to be in the off state, the feedback signal triggers the discharge circuit to activate, creating a closed-loop control system that maintains voltage within safe limits

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11258438B1Control device of power switch

Publication Date: 2022.02.22 EXCELLIANCE MOS

AI summary

A control device of a power switch includes a voltage boost circuit, a discharge circuit and a bias voltage generating circuit. The voltage boost circuit generates a control voltage at a control end of the power switch by boosting a base voltage. The discharge circuit provides a discharge path between the control end of the power switch and a reference ground end according to a bias voltage. The bias voltage generating circuit compares an output voltage on an output end of the power switch with the control voltage to generate a comparison result, and generates the bias voltage according to the comparison result.