1. K UMU A ’ O C UBESAT Amy Blas March 7, 2008 1

2. W HAT IS C UBE S AT ? 10x10x10 centimeter cube Launched in lower earth orbit (LEO) Started last semester 13 members Objective is to be the first CubeSat in space from Hawaii 2

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4. T HE D IFFERENT S UBSYSTEMS Tele-Communication Command and Data Handling (C&DH) Thermal Structural Electrical Power (EPS) 4

5. B LOCK D IAGRAM OF EPS 5 Solar Cells Step Up Converter Battery Charger C&DH Battery Gauge Battery Pack DC-DC Converter Electronic Components

6. B LOCK D IAGRAM OF EPS 6 Solar Cells Step Up Converter Battery Charger C&DH Battery Gauge Battery Pack DC-DC Converter Electronic Components

7. S OLAR C ELLS 26.8% efficiency Solar Cells Integral bypass diode protection Transparent insertion into existing systems 7 Spectro Lab’s Improved Triple Junction (ITJ)

8. 8 S OLAR C ELLS 1 Set = 2 Series Cells 12 cell configuration Each cell is 4 x 7 cm 2.32 V per cell 4.64 V and 450.8 mA per side Bypass Diode Blocking Diode (prevent power drain) 10 cm Current Sensor 10 cm 8

9. C URRENT S ENSORS 1 placed at each side Used to see orientation of Cube Texas Instruments INA138-Q1: High-Side Measurement Current Shunt Monitor 9

10. B LOCK D IAGRAM OF EPS 10 Solar Cells Step Up Converter Battery Charger C&DH Battery Gauge Battery Pack DC-DC Converter Electronic Components

11. S TEP - UP C ONVERTER – MAX1771 11 2 to 16.5V Input Voltage Range 90% Efficient for low load currents Output current range of 30mA to 2A Preset 12 V or adjustable output voltage Set by input voltage of charger 5V

12. B LOCK D IAGRAM OF EPS 12 Solar Cells Step Up Converter Battery Charger C&DH Battery Gauge Battery Pack DC-DC Converter Electronic Components

13. B ATTERY C HARGER – MAX1898 Simple circuit design 4.5 to 12V input range Programmable charge current Output voltage of 4.1V Internal current sense resistor 13

14. B LOCK D IAGRAM OF EPS 14 Solar Cells Step Up Converter Battery Charger C&DH Battery Gauge Battery Pack DC-DC Converter Electronic Components

15. L ITHIUM I ON C ELLS Nominal Voltage: 3.7 V Cycle Life: > 600 cycles @ C/2 to 100% DoD Capacity of 7 Ah Discharge cut off voltage : 2.5 V End charge voltage of 4.2+/-0.05V Saft MP 176065 Lithium Ion cell 15

16. B LOCK D IAGRAM OF EPS 16 Solar Cells Step Up Converter Battery Charger C&DH Battery Gauge Battery Pack DC-DC Converter Electronic Components

17. F UEL G AUGE External EEPROM stores configuration information Battery’s chemistry Self-discharge rate Rate compensation factors Measurement calibration Design voltage and capacity Accurately adjusts remaining capacity for use and standby conditions based on Time Rate Temperature Texas Instruments bq2060A: Compliant Gas Gauge IC 17

18. B LOCK D IAGRAM OF EPS 18 Solar Cells Step Up Converter Battery Charger C&DH Battery Gauge Battery Pack DC-DC Converter Electronic Components

19. DC-DC C ONVERTER MAX1703(step-up) Fixed 5V output voltage Up to 95% efficiency 0.7 to 5.5V input Range Up to 1.5A output 19

20. MAX1703- PCB ARTIST SCHEMATIC 20

21. DC-DC C ONVERTER o MAX 1771 : 6V step-up o 2 to 16.5V Input Voltage Range o 90% Efficient for low load currents o Output current range of 30mA to 2A o Preset 12 V or adjustable output voltage o Set by input voltage of charger o External resistors can be used to set the output voltage 21

22. MAX1771- PCB ARTIST SCHEMATIC 22

23. DC-DC C ONVERTER MAX1921(step-down) Up to 90% efficiency 2 to 5.5V input range Fixed 3.3V output voltage Guaranteed 400 mA output current Up to 1.2MHz switching frequency Operating temperature range of -40 to +85°C 23

24. MAX1921- PCB ARTIST SCHEMATIC 24

25. EPS PCB A RTIST S CHEMATIC 25

26. EPS PCB A RTIST - PCB D ESIGN 26

27. P ROBLEMS Complications with PCB artist Not enough room on PCB Wrong values for resistors, capacitors, etc. Connection errors Running out of Time 27

28. EPS Schedule (Gantt Chart) Week 1234567891011121314151617 JanuaryFebruaryMarchAprilMay Date 142128411182531017243171421285 Presentations Orientation Proposal Preliminary Design Critical Design Final DesignEPS PCB artist Ina 138 Max 1771 Max 1898 Max 1771 Max 1703 BQ 2060A Prototyping Breadboard Ina 138 Max 1771 Max 1898 Max 1703 Max 1771 BQ2060A Test Receive Parts Test PCB layout Combine subsystems Reports Draft Final

29. Any Questions? 29