1. XTR111 Noise/Slew Rate Follow-up Testing Ian Williams 2/23/11

2. Background “Customer X” desires the following performance: –≤ 100µs slew from 10%-90% –≤ 5mVp (10mVpp) AC noise –No RC filter required at load Multiple transmitter-side capacitor values were tested to determine if this is possible

3. Test Circuit Changing R8 alters the output current/voltage, so only C3 was varied in these tests Capacitance values tested: 50nF, 60nF, 70nF, 77nF, 94nF 50-94nF

4. Slew Rate Test #1 C3 = 50nF (5*10nF) 10% to 90% slew time: 72µs

5. Noise Test #1 C3 = 50nF (5*10nF) AC noise: 20.21mVpp

6. Slew Rate Test #2 C3 = 60nF (6*10nF) 10% to 90% slew time: 82µs

7. Noise Test #2 C3 = 60nF (6*10nF) AC noise: 18.00mVpp

8. Slew Rate Test #3 C3 = 70nF (7*10nF) 10% to 90% slew time: 92µs

9. Noise Test #3 C3 = 70nF (7*10nF) AC noise: 16.59mVpp

10. Slew Rate Test #4 C3 = 77nF (47nF + 3*10nF) 10% to 90% slew time: 100µs

11. Noise Test #4 C3 = 77nF (47nF + 3*10nF) AC noise: 15.99mVpp

12. Slew Rate Test #5 C3 = 94nF (2*47nF) 10% to 90% slew time: 123µs

13. Noise Test #5 C3 = 94nF (2*47nF) AC noise: 13.47mVpp

14. Conclusion Using C3 = 77nF provided the best noise performance (8mVp) while still meeting the 100µs 10% to 90% slew requirement If the slew rate requirement is relaxed slightly, the 5mVp noise requirement can be met with a larger C3 value

15. Recommended Application Circuit