Power-On Reset Circuit with Coupled Reference Voltage Startup

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Solution Overview

Problem

Existing power-on reset circuits, such as those described in JP-A-2009-123168, face issues with unstable regulator behavior, leading to unintended reset release due to non-following reference voltage, especially when the power supply voltage rises rapidly, causing the monitoring target voltage to exceed the intended determination voltage prematurely.

Innovation Solution

A circuit device incorporating a comparator, reference voltage generation circuit, and coupling control circuit, where the coupling control circuit couples the reference voltage node and power supply voltage node for a predetermined period after power supply, allowing the reference voltage to converge and stabilize before comparison, ensuring accurate reset and release operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the regulator generates reference voltage quickly to match rapid power supply voltage rise, then the response speed is improved, but the reference voltage becomes unstable and does not converge properly

Engineering Contradiction:

Improveresponse speed of reference voltageVSAvoidstability of reference voltage

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The coupling control circuit performs preliminary action by coupling the reference voltage node to the power supply voltage node before the comparator comparison begins. This allows the reference voltage generation circuit to initialize its reference voltage quickly by directly following the power supply voltage rise, while the coupling control circuit prevents this initial unstable reference voltage from affecting the comparison result. After the predetermined period elapses and the reference voltage stabilizes, the coupling control circuit opens the switch to disconnect the nodes, allowing stable comparison to proceed.

Inventive Principle:

Principle #10Preliminary action

2Loss of time

If the comparator immediately compares voltages upon power supply, then the reset release timing is improved, but the reset is released at unintended voltage due to unstable reference voltage

Engineering Contradiction:

Improvereset release timingVSAvoidaccuracy of reset release

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The coupling control circuit acts as an intermediary between the reference voltage node and the power supply voltage node. It mediates the interaction by temporarily coupling these nodes during the initialization period, allowing the reference voltage to establish itself without directly affecting the comparator's comparison function. This intermediary control ensures that the unstable reference voltage does not cause premature reset release while still allowing quick initialization.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If the reference voltage node is always coupled to power supply voltage node, then the reference voltage follows power supply voltage accurately, but the reference voltage cannot stabilize and converge to proper value

Engineering Contradiction:

Improveaccuracy of voltage followingVSAvoidconvergence of reference voltage

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The coupling control circuit introduces dynamic control by switching the coupling state between the reference voltage node and power supply voltage node based on the initialization stage. During the predetermined initialization period, the switch couples the nodes to allow accurate voltage following. After the predetermined period elapses, the switch opens to disconnect the nodes, allowing the reference voltage to stabilize and converge to its proper value for accurate comparison operations.

Inventive Principle:

Principle #15Dynamics

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 solution prevents premature reset release by ensuring the monitoring target voltage does not exceed the intended determination voltage, allowing for stable reset and release operations even when the reference voltage does not follow the power supply voltage, thus maintaining reliable circuit operation.

Implementation Method 1

The coupling control circuit couples the reference voltage node and the power supply voltage node in a predetermined period after the power supply voltage is supplied

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Implementation Method 2

a comparator configured to output a power-on reset signal by comparing a monitoring target voltage generated from a power supply voltage with a reference voltage

Methodology Applied

Scientific EffectVoltage Comparison:

Data Source

PatentUS11531367B2Circuit device and real-time clock device

Publication Date: 2022.12.20 SEIKO EPSON CORP

AI summary

A circuit device includes a comparator, a reference voltage generation circuit, and a coupling control circuit. The comparator is configured to output a power-on reset signal by comparing a monitoring target voltage generated from a power supply voltage with a reference voltage. The reference voltage generation circuit is configured to generate the reference voltage. The coupling control circuit is coupled between a power supply voltage node and a reference voltage node. The coupling control circuit couples the reference voltage node and the power supply voltage node in a predetermined period after the power supply voltage is supplied.