Digital Input Switching Circuit Cross-Stabilization for Low Power Loss

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Solution Overview

Problem

Existing digital input circuits face challenges in maintaining reliable detection of high-level and low-level states while minimizing power dissipation, particularly in the high-level range, due to non-ideal current consumption behavior and increased power loss as input voltage increases.

Innovation Solution

A digital input circuit design utilizing two interconnected subcircuits with high-value resistors and Zener diodes, where each subcircuit stabilizes the current of the other, ensuring a constant input current in the high-level range, thereby minimizing power loss and maintaining reliable state detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional digital input circuits are used to detect high-level states, then state detection is achieved, but power dissipation increases significantly in the high-level voltage range

Engineering Contradiction:
Improvestate detection reliabilityVSAvoidpower dissipation
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The input circuit is divided into two separate subcircuits: a first subcircuit optimized for detecting low-level states and a second subcircuit optimized for detecting high-level states. Each subcircuit operates independently with its own switching element, allowing the circuit to achieve reliable state detection while minimizing power dissipation by activating only the appropriate subcircuit for each input state.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If the number of digital input circuits is increased to handle more inputs, then input capacity increases, but power dissipation and heat generation increase

Engineering Contradiction:
Improveinput capacityVSAvoidpower dissipation
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The dual-subcircuit design enables a single digital input circuit to handle multiple input types (both sinking and sourcing) and multiple voltage levels efficiently. By making each subcircuit independently controllable and optimizing them for different operating conditions, the circuit achieves multi-functionality that reduces the need for additional dedicated circuits, thereby limiting overall power dissipation.

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

3Reliability

If current consumption is increased to ensure reliable high-level detection, then detection reliability improves, but power loss increases

Engineering Contradiction:
Improvehigh-level detection reliabilityVSAvoidcurrent consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The circuit dynamically adjusts its current consumption characteristics by activating different switching elements based on the input state. The first switching element is activated for low-level detection with optimized current characteristics, while the second switching element is activated for high-level detection with different current characteristics. This dynamic adaptation allows reliable detection across both states while minimizing overall power loss.

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

The circuit achieves a nearly ideal input current-voltage characteristic, reducing power loss and ensuring reliable state detection across varying input voltages, suitable for miniaturized devices with limited power dissipation capacity.

Implementation Method 1

an intermediate resistor (R3), via which the first subcircuit (3) is connected to ground (GND1), and with a Zener diode (Z2), which is connected in parallel to the intermediate resistor (R3)

Methodology Applied
Scientific EffectZener breakdown: Avalanche Breakdown

Data Source

PatentEP3503399B1Digital input switching for receiving digital input signals of a signal provider
Publication Date: 2025.08.20 PILZ GMBH & CO KG
  • EP3503399B1 patent drawingFigure 1~2
  • EP3503399B1 patent drawingFigure 3~4

AI summary

The invention relates to a digital input circuit (100) for receiving digital input signals from a signal transmitter, comprising: - an input (1) via which the input signal can be supplied to the input circuit (100), wherein the input circuit (100) assumes a first state when the input signal reaches or falls below a lower threshold, and wherein the input circuit (100) assumes a second state when the input signal reaches or exceeds an upper threshold; - a first sub-circuit (3) comprising at least one current-stabilizing element (T1) with a control circuit (A1) and at least one voltage-stabilizing element, wherein the first sub-circuit (3) exhibits a non-ideal current output characteristic at least in the second state; and - a second sub-circuit (4) comprising at least one current-stabilizing element (T2) with a control circuit (A2) and at least one voltage-stabilizing element.wherein the second sub-circuit (4) exhibits a non-ideal current output characteristic at least in the second state, wherein the first sub-circuit (3) and the second sub-circuit (4) are designed and interconnected such that at least in the second state, or at least in a part of the second state, an electric current flowing through the voltage-stabilizing element of the first sub-circuit (3) consists essentially of a stabilized current of the second sub-circuit (4), and an electric current flowing through the voltage-stabilizing element of the second sub-circuit (4) consists essentially of a stabilized current of the first sub-circuit (3), such that the non-ideal current output characteristic of the first sub-circuit (3) and the non-ideal current output characteristic of the second sub-circuit (4) essentially compensate each other at least in the second state.