High-Voltage Digital Input Circuit With Latched Low-Power Sensing

Solution Overview

Problem

Digital input modules in industrial automation face high power consumption due to existing methods like resistor divider and current limiter circuits, limiting channel density and requiring larger power supplies.

Innovation Solution

A digital input circuit comprising a series connection of a current limiter and an electronic switch, coupled with a logic level shifter, where the switch is controlled to only draw current when the input signal is above a threshold, and power is saved by latching the output signal and turning off the switch when the signal is processed, reducing overall power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a resistor divider circuit is used to detect high voltage sensor signals, then the circuit can detect both voltage and current thresholds, but power consumption increases quadratically with sensor voltage

Engineering Contradiction:

Improvevoltage and current threshold detectionVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by using a clock signal to periodically enable the electronic switch, allowing current to flow through the current limiter only during specific time intervals. This periodic operation reduces average power consumption while maintaining the ability to detect voltage and current thresholds through sampling the sensor signal at these periodic intervals

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent implements dynamics by using an electronic switch that can dynamically change its state between conducting and non-conducting. The switch is controlled by a clock signal to be conductive only during specific phases, allowing the circuit to adapt its power consumption characteristics while maintaining detection capability through timed sampling of the sensor signal

Inventive Principle:

Principle #15Dynamics

2Use of energy by stationary object

If a current limiter circuit is used to reduce power consumption, then continuous current draw is limited, but power consumption remains significant and channel density is still restricted

Engineering Contradiction:

Improvepower consumptionVSAvoidchannel density

Core Design Contradiction:

Use of energy by stationary objectVSProductivity

Solution Approach 1:

The patent applies periodic action by using a clock signal to periodically enable the electronic switch, allowing current to flow through the current limiter only during specific time intervals. This periodic operation reduces average power consumption while maintaining the ability to detect voltage and current thresholds through sampling the sensor signal at these periodic intervals

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent implements preliminary action by using a latch circuit that captures and stores the sensor signal state during the brief period when the electronic switch is conductive. This preliminary capture of the signal state allows the system to maintain detection capability without requiring continuous current flow, thereby reducing power consumption while enabling higher channel density

Inventive Principle:

Principle #10Preliminary action

3Reliability

If continuous current flows through divider resistors to maintain detection capability, then voltage and current thresholds can be continuously monitored, but power consumption increases

Engineering Contradiction:

Improvesignal detection reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements preliminary action by using a latch circuit that captures and stores the sensor signal state during the brief period when the electronic switch is conductive. This preliminary capture of the signal state allows the system to maintain detection capability without requiring continuous current flow, thereby reducing power consumption while enabling higher channel density

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses an intermediary approach by introducing a latch circuit between the sensor signal and the detection logic. The latch holds the sampled signal state, allowing continuous monitoring capability without continuous current flow through the sensor circuit, thus maintaining reliability while reducing power consumption

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9294063B1Digital input circuit and method for high voltage sensors

Publication Date: 2016.03.22 MAXIM INTEGRATED PROD INC

AI summary

A digital input circuit includes a series connection of a current limiter and a switch having a switch control input coupled between a signal input and ground, and a logic level shifter coupled to the signal input and having a switch control output coupled to the switch control input and a signal output, where a maximum amplitude at the signal input is greater than a maximum amplitude at the signal output. A digital input method includes coupling an input signal to ground with a current limiter by closing an electronic switch, providing an output signal responsive to the input signal, where a maximum amplitude of the input signal is greater than a maximum amplitude of the output signal, by latching the output signal while the input signal is above a threshold voltage and opening the electronic switch after the output signal is latched.