SGAS701 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 low hydrogen concentrations (<10 to 1000 ppm) Fast response time (<15 seconds at 100ppm) Environmental temperature range of -20°C to 50°C Environmental humidity range of 0% to 90% RH, noncondensing Low dependence on flow rate Rugged, reliable sensor based on IDT’s exclusive technology Typical Applications Leak Detection Gas Concentration Detection Breath Detection Available Support Evaluation Kit – SMOD701KITV1 Application Notes Instruction Videos Reference Design
Figure 2. Pin Assignments for SGAS701 – Top View Table 1. Pin Descriptions
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 (ground) input for VH heater voltage supply
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.
- Heater Driver Circuits and Control
to constant temperature) control of the heater.
6.1 Constant Voltage Drive
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. R3, and current through both R3 and RHEATER is thus controlled independently of the load resistance according to the equation in Figure 6. well as the heater. Limiting the supply voltage to several hundred mV above the highest required drive voltage will help increase circuit efficiency. to keep (VHEATER IHEATER) constant. Figure 6. Voltage-Controlled Constant Current Circuit
6.3 Pulse-Width Modulation
sufficient testing at IDT to allow IDT 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 the 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
SGAS701 sensor specifications, refer to Table 4.
7.1 Sensitivity
between the resistance in air (RAir) and the resistance in gas (RGas). Figure 8. Typical Sensor Response to a Range of Hydrogen C oncentrations in a Background
Figure 9. Typical Sensor Sensitivity to a Range of Hydrogen Concentrations in a Background
7.2 Response and Recovery Time
whether the sensor is operated with or without a pump or other source of external flow. Figure 10. Typical Sensor Response to Step Changes in Hydrogen Concentration for Four
7.3 Cross-Sensitivity
The response of the SGAS701 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
- Mechanical Stress Testing
The qualification of the SGAS701 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
- Package Drawing and Dimensions
Figure 12. TO-39 Package (TO4) Outline Drawing PSC-4676
© 2017 Integrated Device Technology, Inc. 16 November 16, 2017 11. Applications and Use Conditions The SGAS701 sensor is designed for gas leak detection and measurement of ppm levels of hydrogen. The sensor is not intended, recom - mended, or approved for use in safety or life protecting applications or in potentially explosive environments . IDT disclaims all liability for such use. 12. Ordering Information Orderable Part Number Package MSL Rating Shipping Packaging Temperature SGAS701 4-pin TO-39 (TO4) 1 Tray -20°C to 50°C SMOD701KITV1 SMOD701 Evaluation Kit, including the SMOD701 Smart Sensing Module (includes the SGAS701 sensor), mini-USB cable, and wall-mounted 9V power supply. The SMOD7xx Application Software is available for download at www.idt.com/SMOD701. 13. Revision History Revision Date Description of Change November 16, 2016 Minor correction. October 25, 2017 Full revision. November 9, 2016 Initial release with 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 support 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 expres s, written 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 res pective 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 r ights reserved.