1. Preliminary Design Review
IDPU Backplane
Preliminary Design Review
Peter Berg
University of California - Berkeley

2. Overview Backplane Overview Requirements Specifications Design
Mass and Power
Schedule
Issues

3. Requirements Fault Protection
IN.BKP-1. The IDPU BKP shall allow route power independently to instrument electronics allowing for autonomous fault protection features to ensure the health and safety of the instruments (ref IN.DPU-11)
Commands/Telemetry
IN.BKP-2. The IDPU BKP shall transport instrument data between instrument cards and the DCB.(ref IN.DPU-15)
IN.BKP-3. The IDPU BKP shall transport engineering telemetry sufficient to safely turn-on and operate all instruments (temperatures, currents, voltages, and bi-levels) as defined in Instrument-IDPU ICDs(ref IN.DPU-16)
IN.BKP-4. The IDPU BKP shall transport operational commands and test programs for all instruments as detailed in the Instrument-IDPU ICDs (ref IN.DPU-17)
IN.BKP-5. The IDPU BKP shall transport initialization parameters to the Instruments as detailed in the Instrument-IDPU ICDs(ref IN.DPU-18)

4. Requirements Power Timing Signals
IN.BKP-6. The IDPU BKP shall distribute a 2^23 Hz Clock from the DCB to the DFB and FGM(ref IN.DPU-23)
IN.BKP-7. The IDPU BKP shall distribute a 1 Pulse Per Second (1PPS) to the DFB and the FGM(ref IN.DPU-25)
IN.BKP-8. The IDPU BKP shall distribute a once-per-spin reference pulse (SRP) to the SST and ESA(ref IN.DPU-27)
IN.BKP-9. The IDPU BKP shall distribute a Spin Sector Clock with 2^14 phase pulses per spin to the ESA and SST (synchronized with the SRP) (ref IN.DPU-28)
IN.BKP-10. The IDPU BKP shall provide ESA and SST synchronization by distributing spin count data from the DCB to these systems. (ref IN.DPU-34)
Power
IN.BKP-11. The IDPU BKP shall transport Instrument regulated, switched and current-limited voltages as detailed in the Instrument-IDPU ICDs(ref IN.DPU-44)
IN.BKP-12. The IDPU BKP shall transport LV transient power to actuators as detailed in the Instrument-IDPU ICDs(ref IN.DPU-45)
Mechanical
IN.BKP-13. The IDPU BKP shall accommodate at least five 6U VME cards(ref IN.DPU-51a)

5. Electrical Specification
Specifications
Electrical Specification
Captured in THM_IDPU_001 revision H
Details Interface Requirements for Each Board
SST : Solid State Telescope Analog-to-Digital Conversion
BEB : Boom Electronics Board
DFB : Digital Fields Board
FGE-PCB: Fluxgate Electronics and Power Control Board
DCB-ETC: Data Controller Board and Esa-ssT Circuit
LVPS : Low Voltage Power Supply connector

6. Electro-Mechanical Specifications
Connectors
VME standard connectors 3x32 format M55302 (Class1)
Mate/Demate Cycles >500
Dielectric isolation >1000V (need 200V)
J1 Location only
Allows use of commercial backplanes for testing
Female connectors (standard) to all boards except LVPS
Male connector to LVPS
Board-to-board Separation
Current Spacing is 0.585”
Driven by Board Heights
Dependent upon tallest parts (e.g. large caps)
Dependent upon electrical shielding
Preliminary height has been checked by board designers

7. Design Considerations
Grounds
5 Digital
8 Analog
7 Power
Digital and Analog Signal Separation
Digital Signals A1-C8
Analog & Power A9-C32
Voltage Capabilities
Worst Case Floating Voltages +/-100V
Isolation >1000V
Current Capabilities
Worst Case Current Req – 2A
Pin 3A

8. Design
PINOUT (THM_IDPU_001H)

9. Design
PINOUT (THM_IDPU_001H)

10. Design
PINOUT (THM_IDPU_001H)

11. Design
PINOUT (THM_IDPU_001H)

12. Specifications
Connector Specifications (Board Interface)

13. Specifications
Connector Specifications (LVPS Interface)

14. Mass & Power Power Mass Unterminated Backplane No power dissipation
Assuming 0.585” board-to-board pitch
Allocation 250 grams

15. Schedule Development Plan
Use Commercial Backplanes DIN41612 for boards
Allow FLT Board Dimensions to Define Spacing as needed
Allow Chassis Fab/Assy Details to Define BKP features
Layout and MIL PWB Fabrication Jan 2004
Coupon Checks at GSFC for Flight Backplanes

16. Issues Issues Board Design, Selection of Components Impact BKP
Any of 5 boards can change BKP dimensions
Recent Addition of SST reduced BKP pin margin to 8%
If Necessary, can reduce Ground pins
Board Height Impacts IDPU ICD Footprint