Communication Interface Reset Circuit Without Dedicated Reset Pins

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Solution Overview

Problem

Integrated circuits (ICs) face challenges in resetting to a known state without dedicated reset terminals or internal power-on reset (POR) circuits, especially when supply voltage is below the operating range, leading to potential malfunctions.

Innovation Solution

The solution involves reusing communication interface terminals, such as SPI or SWD terminals, to generate a reset signal by coupling input circuits to these interfaces, allowing the IC to be reset to a known state without relying on dedicated reset terminals or internal POR circuits, thereby reducing die area and package size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dedicated reset terminals or internal POR circuits are used, then the IC can be reliably reset to a known state, but the die area and package size increase

Engineering Contradiction:

Improvereset reliabilityVSAvoiddie area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The communication interface terminals are designed to serve dual purposes: normal communication functions and reset signal input. The input circuit monitors these existing terminals to detect reset conditions, eliminating the need for separate dedicated reset terminals while maintaining reliable reset functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The reset functionality is merged with the communication interface by using the same terminals for both communication and reset purposes. The input circuit combines signals from communication terminals to generate reset signals, consolidating multiple functions into existing structural elements.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If dedicated reset terminals or internal POR circuits are used, then the IC can be reliably reset to a known state, but the package size increases

Engineering Contradiction:

Improvereset reliabilityVSAvoidpackage size

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Area of stationary object

If communication interface terminals are reused for reset, then die area and package size are reduced, but the reset signal generation becomes more complex

Engineering Contradiction:

Improvedie areaVSAvoidreset signal generation complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The input circuit automatically monitors the communication interface terminals and self-generates the reset signal based on detected signal conditions. The system uses its own existing resources (terminals and input circuitry) to produce the reset function without requiring external dedicated reset circuitry.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The input circuit acts as an intermediary that translates communication interface signals into reset signals. It monitors the communication terminals and generates appropriate reset signals based on detected conditions, bridging between communication functions and reset requirements.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Ease of manufacture

If communication interface terminals are reused for reset, then costs are reduced, but the circuit design becomes more complex

Engineering Contradiction:

Improvemanufacturing costVSAvoidcircuit design complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10979044B2Chip reset via communication interface terminals

Publication Date: 2021.04.13 INFINEON TECHNOLOGIES AG

AI summary

In an embodiment, an integrated circuit includes a communication interface configured to be coupled to a communication bus and an input circuit. The communication interface has a plurality of terminals. The input circuit has a first input coupled to a first terminal of the plurality of terminals, and a second input coupled to a second terminal of the plurality of terminals. The first input of the input circuit is configured to receive a first signal and the second input of the input circuit is configured to receive a second signal. The input circuit is configured to generate a reset signal at an output of the input circuit based on the first and second signals while the communication interface is unselected.