1. Portable Rechargeable Output Power Supply (PROPS) Final Presentation April 24, 2008

2. Team Members Daniel Evans Shane Morrison Drew Mills Josh Gentry

3. Outline: Introduction Problem Statement SolutionConstraintsOperationTestingConclusionReferences

4. Problem Commercial Power Supplies: –Not Portable Bench top and Stationary Can only be used where AC is available Relatively large and heavy

5. Solution Portable Power Supply –Lightweight and Portable –Rechargeable –Variable outputs –Large display to show voltage and current output

6. Proposed Layout

7. Top Level Diagram

8. Technical Constraints Variable output from 1-12 volts ‒ 0.1 volt increments Tracking output from -10 to 10 volts Current up to 3.5 amps Output Ripple Voltage less than 5% Output error no greater than ± 50mV Runtime of 1 hour at full capacity

9. Practical Design Constraints Economic –Manufactured for $120.00 Built in Power Supply Rechargeable Battery Display Screen –Marketed for $250.00

10. Practical Design Constraints Manufacturability –Size 14” x 9” x 7” –Weight < 10 pounds < 10 pounds –Durability

11. Operation Battery/Charger Outputs Voltage and Current Sensing

12. Operation (battery/charger)

13. Battery Specs – –14.8 volts @ 4000 mA/h Charger Specs – –MAX1873 Input voltage up to 28 volts Charge up to 4 cells Charge up to 4 amps

14. Operation (battery/charger) Battery Charging

15. Operation (battery/charger)

16. Operation (Output Circuits) Operation of Circuits – –DC/DC converters – –Linear Regulators

17. Operation (1-12 volt output)

19. Operation (Tracking output)

21. Operation (Current Monitoring) Hall-Effect Sensor ACS713 – –Monitors Current

22. Operation (Current Monitoring)

23. Operation (Software)

24. Video

25. Testing (battery/charger) Vin (V)Vout 1Iout 1Vout 2Iout 2 Time (min) 15.47012.1202.94910.1000.3530.000 15.01012.1102.94010.1500.3545.000 14.69012.1102.94010.1300.35210.000 14.44012.1102.96110.1100.35115.000 14.24012.1102.96310.1100.35120.000 14.07012.0902.96310.1100.35125.000 13.92012.0902.96210.1000.35130.000 13.78012.0502.95210.1100.35135.000 13.66012.0502.96210.1000.35140.000 13.56012.0502.95410.1000.35145.000 13.47012.0502.95510.1000.35150.000 13.38012.0202.95210.1000.35155.000 13.27011.9502.93210.0200.34860.000 Battery Lifetime Test

26. Testing (battery/charger)

27. Testing (1-12 volt output) 1 – 12 volt test data Voltage (measured) Voltage displayed on LCD% Error Difference (V) 1.0781.091.1130.012 1.5271.5350.5240.008 2.022.0250.2480.005 3.043.0550.4930.015 4.014.0370.6730.027 55.0350.7000.035 6.066.110.8250.050 7.17.1390.5490.039 8.058.1060.6960.056 9.049.1040.7080.064 10.0410.1170.7670.077 11.0211.10.7260.080 12.1112.2060.7930.096 Average:0.6230.026

28. Testing (Positive Tracking output) Positive 1.5 – 10 volt Voltage (measured) Voltage displayed on LCD% Error Difference (V) 1.0010.9960.5000.005 1.5251.5091.0490.016 2.052.0390.5370.011 3.033.0190.3630.011 4.0140.2490.010 5.034.9960.6760.034 6.025.9920.4650.028 7.17.0660.4790.034 87.9690.3880.031 9.159.1050.4920.045 10.06100.5960.060 11.0410.970.6340.070 12.0111.950.5000.060 Average:0.5730.020

29. Testing (Negative Tracking Output) Negative 1.5 – 10 volts Voltage (measured)Voltage displayed on LCD% ErrorDifference (V) 0000 -1.504-1.49380.678191490.0102 -2.046-2.03380.596285430.0122 -2.03-2.01780.600985220.0122 -3 00 -4.01-4.00380.154613470.0062 -5.01-5.00480.103792420.0052 -6.01-6.00580.069883530.0042 -7-6.990.142857140.01 -8.02-8.0060.174563590.014 -9-8.97680.257777780.0232 -10.05-10.0240.258706470.026 -11.01-10.9930.154405090.017 -12.06-12.020.331674960.04 Average:0.260672240.0101

30. Testing of Output Current Applied Current with Power Supply (read with Fluke) Current displayed on Display% Error 000 0.1030.08418.45 0.2020.2010.495 0.2970.2883.03 0.40.4041 0.5070.4922.959 0.60.6081.333 0.7020.6950.997 0.8040.8120.995 0.899 0 1.011.0160.594 1.0981.1030.455 1.1971.190.585 1.3041.3070.23 1.3991.3940.357 1.5051.510.332

31. Testing Output Ripple

32. Testing (LCD) LCD RS and R/WLCD Enable and DB7

33. Testing (Rotary Encoders ) Rotary Encoder Signals

34. Testing (Digital Pots) I2C lines to Digital Potentiometers

35. Results vs. Constraints ConstraintPassFail 1-12 Volt Output Tracking Output Output Current Output Ripple Output Error Runtime

36. Future Implementations Rotary Encoders Digital Potentiometers DC/DC Converter

37. Future Implementations (Digital Pots)

38. Future Implementations (Rotary Encoders)

39. Design II Goals Change prototype from a Linear Power Supply to a Switching Power Supply Integrate new Digital Potentiometers into PROPS Integrate Rotary Encoders PCB layout

40. Questions