SGAS711 Flammable Gas Sensor Datasheet Description Features The IDT SGAS711 is a solid-state chemiresistor sensor designed High sensitivity to a wide range of flammable gases to detect flammable gases in air. The SGAS711 sensor uses an Non-specific response capable of being calibrated to detect integrated heater with highly sensitive MOx material tailored for a wide range of flammable gases detection of flammable gases, such as methane, propane, Long lifetime (several years in typical applications) hydrogen, liquefied petroleum gas (LPG), and more. In addition to Typical response time < 30 seconds to 90% of full scale detecting flammable gases, the sensor is also sensitive to other hydrocarbons, such as pentane and R410a, and it can be used for Environmental temperature range: -20C to 50C leak detection. Minimal response to environmental humidity over the range of 0% to 95%, non-condensing The chemiresistor sensors in the IDT SGAS family are based on the principle that metal-oxide materials undergo surface inter- Rugged, reliable sensor based on IDTs exclusive technology actions (physisorption and chemisorption) with gas molecules at TO-39 package elevated temperatures, resulting in a measurable change in electrical resistance. As metal-oxide materials are polycrystalline (i.e., composed of multiple grains with distinct grain boundaries), the adsorbed gases have significant electronic effects on the Typical Applications individual grains. These gas-solid interactions result in a change in Leak Detection electron (or hole) density at the surface (i.e., a space charge Gas Concentration Detection forms), which in turn changes the electrical conductivity of the oxide. IDT has developed a set of nanostructured gas-sensing Process Control materials with excellent sensitivity and stability. Figure 1. Product Photo 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 2017 Integrated Device Technology, Inc. 1 October 24, 2017 SGAS711 Datasheet Contents 1. Pin Assignments ...........................................................................................................................................................................................4 2. Pin Descriptions ............................................................................................................................................................................................4 3. Sensor Specifications ...................................................................................................................................................................................4 4. Sensor Characteristics .................................................................................................................................................................................5 5. Basic Measurement Circuit ...........................................................................................................................................................................6 6. Heater Driver Circuits and Control ................................................................................................................................................................7 6.1 Constant Voltage Drive ........................................................................................................................................................................7 6.2 Constant Current Drive ........................................................................................................................................................................8 6.3 Pulse-Width Modulation .......................................................................................................................................................................8 6.4 Operating the Sensor at Temperature Extremes .................................................................................................................................9 7. Sensing Characteristics ..............................................................................................................................................................................10 7.1 Sensitivity ..........................................................................................................................................................................................10 7.2 Response and Recovery Time ..........................................................................................................................................................11 7.3 Cross-Sensitivity ................................................................................................................................................................................12 8. Maximum ESD Ratings ..............................................................................................................................................................................13 9. Mechanical Stress Testing .........................................................................................................................................................................13 10. Package Drawing and Dimensions .............................................................................................................................................................14 11. Applications and Use Conditions ................................................................................................................................................................15 12. Ordering Information ...................................................................................................................................................................................15 13. Revision History ..........................................................................................................................................................................................15 List of Figures Figure 1. Product Photo ......................................................................................................................................................................................1 Figure 2. Pin Assignments for SGAS711 Top View .........................................................................................................................................4 Figure 3. Typical Sensor Response Characteristic .............................................................................................................................................6 Figure 4. Basic Measurement Circuit ..................................................................................................................................................................6 Figure 5. Three Terminal Voltage Regulator ......................................................................................................................................................7 Figure 6. Voltage-Controlled Constant Current Circuit .......................................................................................................................................8 Figure 7. Recommended Applied Heater Voltage as a Function of Environmental Temperature ......................................................................9 Figure 8. Sensor Response to a Variety of Flammable Gases .........................................................................................................................10 Figure 9. Effect of Different Humidity Levels on Sensor Signal at Ambient Temperature ................................................................................11 Figure 10. Typical Sensor Response to Step Changes in Methane Concentration for Seven SGAS711 Sensors ............................................11 Figure 11. Typical Sensor Response to other Common Gases ..........................................................................................................................12 Figure 12. TO-39 Package (TO4) Outline Drawing PSC-4676 ...........................................................................................................................14 2017 Integrated Device Technology, Inc. 2 October 24, 2017