High-Voltage Bus Holder Circuit Without Static Current

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Solution Overview

Problem

Conventional high voltage tolerant bus holder circuits consume static current, are not suitable for low power applications, and require additional processing steps, increasing manufacturing costs.

Innovation Solution

A high voltage tolerant bus holder circuit utilizing first and second control transistors connected in parallel between the control terminal of a pull-up transistor and a bus, where the first control transistor turns on the pull-up transistor during pull-up mode and the second control transistor turns off the pull-down transistor when the bus voltage exceeds a threshold, using series-connected pull-up and pull-down transistors with a parallel control transistor configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional high voltage tolerant bus holder circuits are used to interface with different voltage systems, then voltage compatibility is improved, but static current consumption increases

Engineering Contradiction:

Improvevoltage compatibilityVSAvoidstatic current consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic control of the pull-up transistor through two control transistors that respond to bus voltage conditions. The first control transistor activates the pull-up transistor during normal operation, while the second control transistor dynamically turns it off when high voltage is detected, eliminating static current consumption while maintaining voltage compatibility.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational state of the pull-up transistor based on voltage parameters. By monitoring bus voltage and adjusting the control signal to the pull-up transistor accordingly, the circuit adapts its electrical characteristics to match different voltage conditions, preventing static current flow during high voltage states while maintaining functionality during normal operation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional high voltage tolerant bus holder circuits are used to ensure proper operation, then reliability is improved, but manufacturing cost increases due to additional processing steps

Engineering Contradiction:

Improveproper operationVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent makes standard CMOS transistors perform multiple functions by adding control mechanisms. The pull-up transistor serves both as a normal pull-up device and as a high voltage protection element when controlled by the second control transistor. This multi-functionality eliminates the need for special high voltage tolerant devices, reducing manufacturing complexity and cost while maintaining reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The circuit uses itself to protect against high voltage conditions. The second control transistor monitors the bus voltage and automatically disables the pull-up transistor when high voltage is detected, without requiring external protection circuits or special processing. This self-protecting mechanism maintains reliability while avoiding additional manufacturing steps.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If conventional high voltage tolerant bus holder circuits are used to interface with legacy devices, then adaptability is improved, but device complexity increases

Engineering Contradiction:

Improveinterface capabilityVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the control function into two separate control transistors with distinct roles. The first control transistor handles normal pull-up operation, while the second control transistor specifically handles high voltage protection. This segmentation of control functions simplifies the overall circuit design compared to using complex high voltage tolerant devices, as each transistor has a clear, simple function.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8283947B1High voltage tolerant bus holder circuit and method of operating the circuit

Publication Date: 2012.10.09 NXP BV

AI summary

A high voltage tolerant bus holder circuit and method of operating the bus holder circuit utilizes first and second control transistors connected in parallel between a control terminal of a pull-up transistor and a bus. The first control transistor is used to turn on the pull-up transistor during a pull-up mode of operation. The second control transistor is used to turn off the pull-down transistor when a voltage on the bus exceeds a threshold.