Interface Voltage Switching Circuit for Stable Signal Levels

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Solution Overview

Problem

Conventional interface voltage switching techniques require dedicated terminals for each voltage level, leading to compatibility issues with existing interface specifications and unreliable voltage switching during operation, as they cannot determine if the voltage switching is completed successfully between host and slave devices.

Innovation Solution

An interface circuit with a clock output unit, terminal group, and interface voltage switching unit that selects between two interface voltages, controls the clock signal, and monitors input/output terminal signals to ensure stable and reliable voltage switching without additional terminals, using a control unit to verify successful switching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If dedicated terminals are added for each interface voltage level, then voltage switching capability is improved, but device complexity and terminal count increase

Engineering Contradiction:
Improvevoltage switching capabilityVSAvoidterminal count
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The existing interface terminals are made multi-functional by enabling them to operate at multiple voltage levels (1.8V and 3.3V). The interface circuit dynamically adapts to different voltage levels without requiring dedicated terminals for each voltage, thus maintaining compatibility while achieving voltage switching capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The interface circuit changes its operating voltage parameter dynamically based on the connected device. By detecting the voltage level and adjusting its own operating voltage accordingly, the circuit achieves adaptability without adding physical terminals, resolving the contradiction between versatility and complexity.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If voltage switching is performed during operation, then processing speed is improved, but reliability deteriorates due to inability to verify switching completion

Engineering Contradiction:
Improveprocessing speedVSAvoidvoltage switching reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The interface circuit incorporates a feedback mechanism that monitors the completion of voltage switching between host and slave devices. By detecting whether the voltage transition has been successfully completed, the system ensures reliable operation before resuming data transmission, thus maintaining both speed and reliability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

Before resuming normal operation after voltage switching, the system performs preliminary verification to confirm that the voltage transition is complete. This preliminary check ensures that subsequent operations occur at the correct voltage level, preventing errors and maintaining reliability during high-speed operation.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If interface voltage is lowered to increase processing speed, then productivity is improved, but compatibility with existing interfaces deteriorates

Engineering Contradiction:
Improveprocessing speedVSAvoidinterface compatibility
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The interface circuit employs dynamic voltage adjustment, automatically adapting its operating voltage based on the connected device's requirements. This dynamic behavior allows the circuit to operate at lower voltages (1.8V) for high-speed processing when needed, while automatically switching to higher voltages (3.3V) to maintain compatibility with existing interfaces, thus resolving the contradiction between speed and compatibility.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2249227B1Interface device for host device, interface device for slave device, host device, slave device, communication system and interace voltage switching method
Publication Date: 2015.05.27 PANASONIC HOLDINGS CORP
  • EP2249227B1 patent drawingFigure 1
  • EP2249227B1 patent drawingFigure 2
  • EP2249227B1 patent drawingFigure 3

AI summary

A communication system in which an operating voltage can be selected from a plurality of interface voltages enables an interface voltage to be switched in a stable manner during operation of the system. When the interface voltage is to be switched, a host device (1) and a slave device (2) perform the switching while maintaining the signal level of buses in a stable manner. This structure enables the communication system to switch an interface voltage using a small number of signal lines.