Fail-Safe I/O Voltage Switching for Backflow-Free Power-On

Solution Overview

Problem

Existing input/output devices face issues with improper voltage selection during power-on, leading to current backflow and unexpected voltage drops or jumps, causing instability in system circuits.

Innovation Solution

A fail-safe input/output device incorporating a comparator circuit and resistance adjustment circuit to selectively transmit and adjust voltages, ensuring only the higher voltage is output as the driving voltage, preventing current backflow and voltage jumps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If an input/output device outputs a supply voltage during power-on without fail-safe mechanism, then the device can operate in high performance mode with higher supply voltage, but current backflow or simultaneous selection of multiple supply voltages may occur causing voltage drop or jump

Engineering Contradiction:

Improvesupply voltage levelVSAvoidsystem stability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The resistance adjustment circuit proactively adjusts the resistance value before the voltage switching occurs during power-on. By preemptively setting the resistance to an appropriate level, the circuit prevents current backflow and simultaneous voltage selection before they can happen, ensuring stable voltage transitions from low levels to target levels.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The resistance adjustment circuit acts as an intermediary element between the first supply voltage and the second supply voltage. By controlling the resistance value, it mediates the interaction between the two voltage sources, preventing direct conflict and current backflow while enabling smooth voltage transitions during the power-on sequence.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If voltage switching occurs during power-on without proper control, then the system can transition from low levels to target levels, but improper operation such as current backflow occurs incurring unexpected voltage drop or jump

Engineering Contradiction:

Improvevoltage transition speedVSAvoidcurrent backflow and voltage fluctuation

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The comparator circuit continuously monitors the voltage levels and provides feedback control. By comparing the actual voltage state with the desired state, the feedback mechanism adjusts the resistance adjustment circuit to prevent current backflow and voltage fluctuations, ensuring controlled and stable voltage transitions during power-on.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The resistance adjustment circuit proactively adjusts the resistance value before the voltage switching occurs during power-on. By preemptively setting the resistance to an appropriate level, the circuit prevents current backflow and simultaneous voltage selection before they can happen, ensuring stable voltage transitions from low levels to target levels.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If multiple supply voltages are used for different operating modes, then the system can switch between high performance and power-saving modes, but voltage selection errors may occur during power-on causing circuit instability

Engineering Contradiction:

Improveoperating mode flexibilityVSAvoidcircuit stability during power-on

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The resistance adjustment circuit proactively adjusts the resistance value before the voltage switching occurs during power-on. By preemptively setting the resistance to an appropriate level, the circuit prevents current backflow and simultaneous voltage selection before they can happen, ensuring stable voltage transitions from low levels to target levels.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The resistance adjustment circuit acts as an intermediary element between the first supply voltage and the second supply voltage. By controlling the resistance value, it mediates the interaction between the two voltage sources, preventing direct conflict and current backflow while enabling smooth voltage transitions during the power-on sequence.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12470121B2Fail-safe input/output device and voltage switching method

Publication Date: 2025.11.11 SIGMASTAR TECH LTD

AI summary

A fail-safe input/output device includes an input/output circuit, a comparator circuit and a resistance adjustment circuit. The input/output circuit transmits a voltage having a higher voltage level in a first supply voltage and a second supply voltage to a first node to generate a driving voltage, wherein a first target level of the first supply voltage is lower than a second target level of the second supply voltage. The comparator circuit compares the first supply voltage with the second supply voltage to generate a control signal, and selectively transmits the first supply voltage to the first node according to the control signal. The resistance adjustment circuit adjusts a resistance between the first node and a second node according to the second supply voltage, wherein the input/output circuit transmits the second supply voltage to the first node via the second node.