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© 2017 Integrated Device Technology, Inc.
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