SGAS707 Industrial Organic Chemical Sensor Datasheet Description Features The IDT SGAS707 is a solid-state chemiresistor sensor designed High sensitivity to a wide range of VOCs to detect volatile organic chemicals (VOCs) in air. The sensor uses Non-specific: responds to many different organic vapors an integrated heater with highly sensitive polymer-MOx composite Typical response time < 1 minute to 90% full scale material designed for detection of VOCs. Environmental temperature range: 0C to 40C The chemiresistor sensors in the IDT SGAS family are based on Environmental humidity range: 0% to 90% RH, the principle that metal-oxide materials undergo surface inter- noncondensing actions (physisorption and chemisorption) with gas molecules at 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), Typical Applications the adsorbed gases have significant electronic effects on the Indoor Air Quality individual grains. These gas-solid interactions result in a change in electron (or hole) density at the surface (i.e., a space charge forms), Ventilation Control which in turn changes the electrical conductivity of the oxide. IDT Air Purification has developed a set of nanostructured gas-sensing materials with Gas Concentration Detection excellent sensitivity and stability. Figure 1. Product Photo Examples of Target Gases Formaldehyde Toluene Xylenes Acetone Isobutylene Octane Alcohols Available Support Evaluation Kit SMOD707 Smart Sensing Module Application Notes Instruction Videos Reference Design 2017 Integrated Device Technology, Inc. 1 October 25, 2017 SGAS707 Datasheet Contents 1. Pin Assignments ...........................................................................................................................................................................................3 2. Pin Descriptions ............................................................................................................................................................................................3 3. Sensor Specifications ...................................................................................................................................................................................3 4. Sensor Characteristics .................................................................................................................................................................................4 5. Basic Measurement Circuit ...........................................................................................................................................................................5 6. Heater Driver Circuits and Control ................................................................................................................................................................6 6.1 Constant Voltage Drive ........................................................................................................................................................................6 6.2 Constant-Current Drive ........................................................................................................................................................................6 6.3 Pulse-Width Modulation .......................................................................................................................................................................7 6.4 Operating the Sensor at Temperature Extremes .................................................................................................................................8 7. Sensing Characteristics ................................................................................................................................................................................9 7.1 Sensitivity ............................................................................................................................................................................................9 7.2 Cross-Sensitivity ................................................................................................................................................................................12 8. Maximum ESD Ratings ..............................................................................................................................................................................13 9. Mechanical Stress Testing .........................................................................................................................................................................13 10. Package Drawing and Dimensions .............................................................................................................................................................14 11. Ordering Information ...................................................................................................................................................................................15 12. Revision History ..........................................................................................................................................................................................15 List of Figures Figure 1. Product Photo ......................................................................................................................................................................................1 Figure 2. TO-39 (TO4) Pin Assignments for SGAS707 Top View ...................................................................................................................3 Figure 3. Typical Sensor Response Characteristic .............................................................................................................................................5 Figure 4. Basic Measurement Circuit ..................................................................................................................................................................5 Figure 5. Three-Terminal Voltage Regulator ......................................................................................................................................................6 Figure 6. Voltage-Controlled Constant-Current Circuit .......................................................................................................................................7 Figure 7. Recommended Applied Heater Voltage as a Function of Environmental Temperature ......................................................................8 Figure 8. Typical Sensor Response to a Variety of Organic Chemicals .............................................................................................................9 Figure 9. Typical Sensor Sensitivity to a Variety of Organic Chemicals ...........................................................................................................10 Figure 10. Effect of Different Humidity Levels on the Sensor Signal at Ambient Temperature...........................................................................11 Figure 11. Response of the SGAS707 Sensor to Other Industrial Gases ..........................................................................................................12 Figure 12. TO-39 Package (TO4) Outline Drawing PSC-4676 ...........................................................................................................................14 List of Tables Table 1. TO-39 (TO4) Pin Descriptions .............................................................................................................................................................3 Table 2. Electrical Characteristics .....................................................................................................................................................................3 Table 3. Temperature Specifications .................................................................................................................................................................4 Table 4. Maximum ESD Ratings .....................................................................................................................................................................13 Table 5. Mechanical Stress Test Conditions ...................................................................................................................................................13 2017 Integrated Device Technology, Inc. 2 October 25, 2017