Slew rate detection circuit

Patent metadata

Field	Value
Publication number	US-9285286-B2
Application number	US-201414150416-A
Country	US
Kind code	B2
Filing date	Jan 8, 2014
Priority date	Jan 8, 2014
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

A sensing system comprising a sensor for generating an analog electrical signal indicative of a sensed physical property and an A/D converter for converting the analog electrical signal into a digital electrical signal. A control circuit connected to the A/D converter is configured to receive the digital electrical signal and to perform a plurality of sensing system operations including determining a measurement value of the physical property as a function of said received digital electrical signal. A slew rate detection circuit connected to the sensor is configured to detect when the analog electrical signal indicates a slew rate that exceeds a threshold value, and to generate an interrupt electrical signal when the slew rate is detected as exceeding the threshold value. The control circuit determines a measurement value of the physical property in response to receiving the interrupt signal.

First claim

What is claimed is:

1. A sensing system comprising:
a mechanical component configured to produce a response to a physical property;
an electrical component in communication with the mechanical component for generating an analog electrical signal indicative of the response produced by the mechanical component;
an analog-to-digital (A/D) converter connected to the electrical component, said A/D converter configured to convert the analog electrical signal into a digital electrical signal;
a control circuit connected to the A/D converter for receiving the digital electrical signal and performing a plurality of sensing system operations including determining a measurement value of the physical property as a function of said received digital electrical signal, and generating an output electrical signal indicative of said determined measurement value; and
a slew rate detection circuit connected to the electrical component for receiving the analog electrical signal produced by the electrical component, said slew rate detection circuit configured to detect when the analog electrical signal indicates a slew rate that exceeds a threshold value, and to generate an interrupt electrical signal when the slew rate is detected as exceeding the threshold value; and
wherein the control circuit is connected to the slew rate detection circuit for receiving the interrupt electrical signal from the slew rate detection circuit and determining a measurement value of the physical property in response to the interrupt signal indicating the slew rate exceeded the threshold value.

2. The sensing system of claim 1 , wherein the mechanical component and the electrical component are components of a pressure sensor, and the physical property is applied pressure.

3. The sensing system of claim 1 , wherein said slew rate detection circuit is further configured to detect when the analog electrical signal indicates a pressure step, said pressure step indicating that the slew rate exceeds the threshold value.

4. The sensing system of claim 1 , wherein the slew rate detection circuit comprises:
a differentiator for receiving the analog electrical signal and determining a difference between successive values thereof and generating a differential signal having a magnitude proportional to the determined difference; and
a comparator connected to the differentiator for receiving the differential signal and comparing the magnitude of the differential signal to the threshold value.

5. The sensing system of claim 1 , wherein said slew rate detection circuit is further configured to detect when the analog electrical signal indicates a slew rate that exceeds a first threshold value when the analog electrical signal is rising and to detect when the analog signal indicates a slew rate that exceeds a second threshold value when the analog signal is falling.

6. The sensing system of claim 1 , further comprising an additional mechanical component and an additional electrical component in communication with the additional mechanical component for generating an additional analog electrical signal indicative of the response produced by the additional mechanical component, and wherein the A/D converter is further configured to alternately convert each of the analog electrical signal and the additional analog electrical signal into digital electrical signals.

7. The sensing system of claim 6 , wherein the control circuit is configured to, in response to receiving the interrupt electrical signal, cause the A/D converter to convert the analog electrical signal from the electrical component rather than the additional analog electrical signal from the additional electrical component.

8. A sensing system comprising:
a first sensor for generating a first analog electrical signal representing a first sensed physical property, wherein the first sensor comprises:
a first mechanical component configured to produce a response to a first physical property;
a first electrical component in communication with the first mechanical component for generating the first analog electrical signal indicative of the response produced by the first mechanical component;

a second sensor for generating a second analog electrical signal representing a second sensed physical property, wherein the second sensor comprises:
a second mechanical component configured to produce a response to a second physical property;
a second electrical component in communication with the second mechanical component for generating the second analog electrical signal indicative of the response produced by the second mechanical component;

an analog-to-digital (A/D) converter connected to the first electrical component and to the second electrical component, said A/D converter configured to alternately convert the first analog electrical signal into a first digital electrical signal and the second analog electrical signal into a second digital electrical signal;
a control circuit connected to the A/D converter for receiving the first digital electrical signal and the second digital electrical signal, said control circuit configured to determine a measurement value of the first physical property as a function of the received first digital electrical signal, and to generate an output electrical signal indicative of the determined measurement value; and
a slew rate detection circuit connected to the at least one electrical component for receiving the first analog electrical signal produced by the first electrical component, said slew rate detection circuit configured to detect when the first analog electrical signal indicates a slew rate that exceeds a threshold value; and
wherein the A/D converter is further configured to convert the first analog electrical signal into a first digital electrical signal rather than converting the second analog electrical signal into a second digital electrical signal in response to the slew rate detection circuit detecting that the first analog electrical signal indicates a slew rate that exceeds a threshold value.

9. The sensing system of claim 8 , wherein the first sensor is a pressure sensor, and the physical property is applied pressure.

10. The sensing system of claim 8 , wherein the second sensor is a temperature sensor, and the physical property is temperature.

11. The sensing system of claim 8 , wherein the slew rate detection circuit is further configured to generate an interrupt signal when the slew rate detection circuit detects that the first analog electrical signal indicates a slew rate that exceeds a threshold value.

12. The sensing system of claim 11 , wherein the A/D converter is configured by the control circuit and, in response to the control circuit receiving the interrupt signal, converts the first analog electrical signal into a first digital electrical signal rather than converting the second analog electrical signal into a second digital electrical signal.

13. The sensing system of claim 8 , wherein said slew rate detection circuit is further configured to detect when the first analog electrical signal indicates a pressure step, said pressure step indicating that the slew rate exceeds the threshold value.

14. The sensing system of claim 8 , wherein the slew rate detection circuit comprises:
a differentiator for receiving the first analog electrical signal and determining a difference between successive values thereof and generating a differential signal having a magnitude proportional to the determined difference; and
a comparator connected to the differentiator for receiving the differential signal and comparing the magnitude of the differential signal to the threshold value.

Assignees

• Invensys Sys Inc

Inventors

• Slechta William M

Classifications

• G01L9/0041 Primary

  Transmitting or indicating the displacement of flexible diaphragms · CPC title

• H03K19/00361

  in field effect transistor circuits · CPC title

• G01L13/025

  using diaphragms · CPC title

• G05D1/0883

  Physics · mapped topic

• G05B23/0235 Primary

  based on a comparison with predetermined threshold or range, e.g. "classical methods", carried out during normal operation; threshold adaptation or choice; when or how to compare with the threshold · CPC title