SGAS701 Trace Hydrogen (H ) Sensor Datasheet 2 Description Features The IDT SGAS701 is a solid-state chemiresistor sensor designed High sensitivity to low hydrogen concentrations to detect hydrogen in air. The sensor uses an integrated heater with (<10 to 1000 ppm) highly sensitive MOx material tailored for detection of hydrogen. Fast response time (<15 seconds at 100ppm) The chemiresistor sensors of IDTs SGAS family are based upon Environmental temperature range of -20C to 50C the principle that metal oxide materials undergo surface inter- Environmental humidity range of 0% to 90% RH, actions (physisorption and chemisorption) with gas molecules at noncondensing elevated temperatures, resulting in a measurable change in Low dependence on flow rate electrical resistance. As these materials are polycrystalline (i.e., Rugged, reliable sensor based on IDTs exclusive technology composed of multiple grains with distinct grain boundaries), the adsorbed gases have significant electronic effects on the individual grains. These gas-solid interactions result in a change in electron (or hole) density at the surface (i.e., a space charge forms), which Typical Applications in turn changes the electrical conductivity of the oxide. IDT has developed a set of nanostructured gas sensing materials with Leak Detection excellent sensitivity and stability. Gas Concentration Detection Breath Detection Figure 1. Product Photo Available Support Evaluation Kit SMOD701KITV1 Application Notes Instruction Videos Reference Design 2017 Integrated Device Technology, Inc. 1 November 16, 2017 SGAS701 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 ..........................................................................................................................................................12 7.3 Cross-Sensitivity ................................................................................................................................................................................13 8. Maximum ESD Ratings ..............................................................................................................................................................................14 9. Mechanical Stress Testing .........................................................................................................................................................................14 10. Package Drawing and Dimensions .............................................................................................................................................................15 11. Applications and Use Conditions ................................................................................................................................................................16 12. Ordering Information ...................................................................................................................................................................................16 13. Revision History ..........................................................................................................................................................................................16 List of Figures Figure 1. Product Photo ......................................................................................................................................................................................1 Figure 2. Pin Assignments for SGAS701 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. Typical Sensor Response to a Range of Hydrogen Concentrations in a Background of 30% RH at Room Temperature ................10 Figure 9. Typical Sensor Sensitivity to a Range of Hydrogen Concentrations in a Background of 30% RH at Room Temperature ................11 Figure 10. Typical Sensor Response to Step Changes in Hydrogen Concentration for Four SGAS701 Sensors ..............................................12 Figure 11. Typical Sensor Response to other Common Gases ..........................................................................................................................13 Figure 12. TO-39 Package (TO4) Outline Drawing PSC-4676 ...........................................................................................................................15 2017 Integrated Device Technology, Inc. 2 November 16, 2017