OTPROM-Based Protection Switch Circuit for Software-Configurable Thresholds

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Solution Overview

Problem

Existing protection switch circuits require hardware processing to adjust thresholds, increasing manufacturing costs and limiting user adjustability, especially when the input voltage is used as a power supply.

Innovation Solution

Incorporating an OTPROM and comparator circuit that allows software-controlled setting of threshold voltages, eliminating the need for hardware processing and enabling post-manufacturing adjustments by users.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If hardware processing (fuse-trimming, zapping) is used to adjust thresholds, then threshold adjustment is achieved, but manufacturing cost increases

Engineering Contradiction:

Improvethreshold adjustment capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The patent replaces hardware processing methods (fuse-trimming, zapping) with a software-based approach using an OTPROM memory cell. The threshold adjustment is achieved by changing the conductive state of the memory cell through electrical programming rather than physical modification, eliminating the need for laser cutting or electric current fusing processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state of the memory cell (conductive or non-conductive) to represent different threshold voltage settings. By programming the memory cell to different states, the threshold can be adjusted without hardware modification, enabling flexible parameter adjustment while maintaining manufacturing simplicity.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If hardware processing is used to adjust thresholds, then threshold setting is possible, but user adjustability after manufacturing is lost

Engineering Contradiction:

Improveuser adjustabilityVSAvoidadjustment process complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces irreversible hardware processing with a software-programmable memory cell that can be electrically programmed after manufacturing. This allows users to adjust thresholds by simply writing to the OTPROM memory cell without requiring complex hardware modification equipment or processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The OTPROM memory cell is prepared in advance during manufacturing but remains unprogrammed or pre-programmed with default values. Users can later program the desired threshold values by applying specific voltage sequences to the memory cell, enabling post-manufacturing adjustment while keeping the device structure simple.

Inventive Principle:

Principle #10Preliminary action

3Use of energy by moving object

If input voltage is used as power supply, then power efficiency is improved, but register read/write capability is lost

Engineering Contradiction:

Improvepower supply efficiencyVSAvoidregister access capability

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The patent uses the input voltage itself as the power supply for the OTPROM programming process. By utilizing the available input voltage (when it exceeds the programming threshold VPOR), the system can program the memory cell without requiring an external power supply, thus maintaining power efficiency while enabling register write capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system uses its own input voltage to power the programming operation of the OTPROM memory cell. When the input voltage exceeds the programming threshold, the circuit automatically enables programming mode, allowing the device to configure itself without external intervention or additional power sources.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces manufacturing costs, allows flexible threshold setting by manufacturers and users, and integrates the protection switch circuit on a single semiconductor substrate, reducing area and maintaining circuit characteristics.

Implementation Method 1

an OTPROM (One Time Programmable Read Only Memory) to which N pieces of setting data indicative of each of N threshold voltages can be written

Methodology Applied

Scientific EffectCharge trapping in floating gate:

Implementation Method 2

a comparator circuit that compares the input voltage with each of the N threshold voltages according to the N pieces of the setting data written to the OTPROM

Methodology Applied

Scientific EffectVoltage comparison:

Data Source

PatentUS9941716B2Protection switch circuit, charging circuit, and electronic device

Publication Date: 2018.04.10 ROHM CO LTD

AI summary

A protection switch circuit includes: an input terminal configured to receive a DC input voltage; an output terminal; a switch provided between the input terminal and the output terminal; a determination circuit configured to compare the input voltage with N threshold voltages (N is a natural number); and a gate controller configured to control the switch based on a comparison result of the determination circuit, wherein the determination circuit includes: an OTPROM (One Time Programmable Read Only Memory) to which N pieces of setting data indicative of each of the N threshold voltages are written under software control, and a comparison circuit configured to compare the input voltage with each of the N threshold voltages according to the N pieces of the setting data written to the OTPROM.