SGAS711 IDT | Alldatasheet

Document overview

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Technical content

Datasheet sections

  • 6.1 Constant Voltage Drive
  • 6.2 Constant Current Drive
  • 6.3 Pulse-Width Modulation
  • 6.4 Operating the Sensor at Temperature Extremes
  • 7.1 Sensitivity
  • 7.2 Response and Recovery Time
  • 7.3 Cross-Sensitivity

Features

 High sensitivity to a wide range of flammable gases  Non-specific response; capable of being calibrated to detect a wide range of flammable gases  Long lifetime (several years in typical applications)  Typical response time < 30 seconds to 90% of full scale  Environmental temperature range: -20°C to 50°C  Minimal response to environmental humidity over the range of 0% to 95%, non-condensing  Rugged, reliable sensor based on IDT’s exclusive technology  TO-39 package Typical Applications  Leak Detection  Gas Concentration Detection  Process Control Examples of Target Gases  Hydrocarbons (HC)  Hydrogen  Liquid Petroleum Gas (LPG)  Methane  Natural Gas  Propane  Pentane  R410a Available Support  Evaluation kit – SMOD711 Smart Sensing Module  Application notes  Instruction videos  Reference designs

Figure 2. Pin Assignments for SGAS711 – Top View Table 1. Pin Descriptions Note: See Figure 4 for the connections described below.

1 Heater + Positive input for VH heater voltage supply

2 Sensor + High-side of resistive sensor element; positive input for sensing voltage VC

3 Heater – Negative input for VH heater voltage supply (ground)

Note: All measurements were made in dry gas at room temperature. Specifications are subject to change. Table 2. Electrical Specifications

Table 3. Temperature Specifications durations will not will not harm the sensor. orders of magnitude across the sensing range. This shows that log resistance versus log concentration is linear. circuitry exacerbate these challenges and must be understood in order to account for or eliminate these effects.

  1. Heater Driver Circuits and Control

constant temperature) control of the heater.

6.1 Constant Voltage Drive

the temperature of the heater (and consequently gas sensitivity), voltage regulation is required. An easily implemented control circuit utilizes a three terminal voltage regulator, with the LM317 serving as an example as shown in Figure 5. Figure 5. Three Terminal Voltage Regulator three terminal voltage regulators is available from component manufacturers.

6.2 Constant Current Drive

and feedback control of the heater is possible through a simple measurement of the resultant voltage on the heater. well as the heater. Limiting the supply voltage to several hundred mV above the highest required drive voltage will help increase circuit efficiency. Figure 6. Voltage-Controlled Constant Current Circuit

6.3 Pulse-Width Modulation

sufficient testing at IDT to allow us to recommend it for any sensors in the SGAS family.  Voltage to the heater should not exceed the maximum voltage allowed for a given heater family.  A low-pass filter should be considered as part of the sensor signal circuit path to reduce noise from heater PWM.

6.4 Operating the Sensor at Temperature Extremes

temperature set point voltage versus environmental temperature is shown in Figure 7. Figure 7. Recommended Applied Heater Voltage as a Function of Environmental Temperature

sensor specifications, refer to Table 2.

7.1 Sensitivity

the resistance in air (RAir) and the resistance in gas (RGas). Figure 8. Sensor Response to a Variety of Flammable Gases

The typical response of the sensor to changes in humidity is shown in Figure 9. Figure 9. Effect of Different Humidity Levels on Sensor Signal at Ambient Temperature

7.2 Response and Recovery Time

operated with or without a pump or other source of external flow. Figure 10. Typical Sensor Response to Step Changes in Methane Concentration for Seven

7.3 Cross-Sensitivity

The response of the SGAS711 sensors to a range of other common gases is shown in Figure 11. Figure 11. Typical Sensor Response to other Common Gases

Table 4. Maximum ESD Ratings

  1. Mechanical Stress Testing

The qualification of the SGAS711 is based on the JEDEC standard (JESD47). given in this document. For information on constant acceleration test conditions and limits, contact IDT (see contact information on last page). Table 5. Mechanical Stress Test Conditions

  1. Package Drawing and Dimensions

Figure 12. TO-39 Package (TO4) Outline Drawing PSC-4676

© 2017 Integrated Device Technology, Inc. 15 October 24, 2017 11. Applications and Use Conditions The SGAS711 sensor is designed for gas leak detection and measurement of ppm levels of flammable gases. The sensor is not intended, recommended, or approved for use in safety or life-protecting applications or in potentially explosive environments. IDT disclaims all liability for such use. For sensor storage, IDT strongly recommends a dust and VOC free atmosphere, e.g. in synthetic air. 12. Ordering Information Orderable Part Number Description and Package MSL Rating Shipping Packaging Temperature SGAS711 4-pin TO-39 (TO4) 1 Tray -20°C to +50°C SMOD711KITV1 SMOD711 Evaluation Kit, including the SMOD711 Smart Sensing Module (includes the SGAS711 sensor), mini-USB cable, and wall-mounted 9V power supply. The SMOD7xx Application Software is available for download at www.idt.com/SMOD711. 13. Revision History Revision Date Description of Change October 24, 2017 Full revision. November 4, 2016 Changed to IDT branding. Corporate Headquarters

6024 Silver Creek Valley Road

San Jose, CA 95138 www.IDT.com Sales 1-800-345-7015 or 408-284-8200 Fax: 408-284-2775 www.IDT.com/go/sales Tech Support www.IDT.com/go/support DISCLAIMER Integrated Device Technology, Inc. (IDT) and its affiliated companies (herein referred to as “IDT”) reserve the ri ght to modify the products and/or specifications described herein at any time, without notice, at IDT's sole discretion. Performanc e specifications and operating parameters of the described products are determined in an independent state and are not guaran teed to perform the same way when installed in customer products. The information contained herein is provided without representati on or warranty of any kind, whether express or implied, including, but not limited to, the suitability of IDT's products for any particular purpose, an implied warranty of merchantability, or non -infringement of the intellectual property rights of others. This document is presented only as a guide and does not convey any license under intellectual property rights of IDT or any third parties. IDT's products are not intended for use in applications involving extreme environmental conditions or in life suppor t systems or similar devices where the failure or malfunction of an IDT product can be reasonably expected to significantly affect the health or safety of users. Anyone using an IDT product in such a manner does so at their own risk, absent an express, wri tten agreement by IDT. Integrated Device Technology, IDT and the IDT logo are trademarks or registered trademarks of IDT and its subsidiaries in the United States and other countries. Other trademarks used herein are the property of IDT or their respectiv e third party owners. For datasheet type definitions and a glossary of common terms, visit www.idt.com/go/glossary . All contents of this document are copyright of Integrated Device Technology, Inc. All rights reserved.