# Presentation: 871747

## MAXIM Periscope Module

**Electrical Design Estimates**
**C. Paul Earle**
**25 April 2003**

## Design Assumptions

-    Unregulated  + 28V Supply from the S/C
-   1 pps timing signal + S/C time from the S/C
-    MIL-STD-1553 Command & Data Handling Interface
- _Requirements_
-    Provide regulated power to Sensors, Actuators, & Circuit Boards
-    Time-Tag Sensor Data (ie. tip/tilt/piston) based on 1pps signal from S/C
-    Implement Thermal Control & Monitoring
-    Collect Housekeeping Data – Temperatures, Voltages, Currents

## Functional Block Diagram

** ****1pps (1Hz)**

**Instrument Electronics**

**RAM**

**1553 I/F**

**S/C C&DH**

- _Figure 1._

**+28V Survival**
**Power**

**Periscope **
**(1 of 4)**

**Actuators (4)**

**H/K & Thermal**
**Control**

- Sensors:
- Encoders (3)
- Tip/tilt (2)

**Mechanism**
**Drive**
**&**
**Control**

**DC/DC**
**Converter**

**InstrumentCPU**

_**Spacecraft**_

_**Instrument**_

**+28V Supply**

- Aperture
- Motor (1)

- Heaters
-  & Temp
- Sensors

## Instrument Architecture

**Power**
**Board**

**H/K **
**& Therm**
**Board**

**BUS**

**CPU**
**Board**
**(+RAM)**

**Mech**
**Drive **
**Board**

- Actuators

**1pps**

**1553 I/F**

**+28V**
**(Unregulated)**

**Address & Data Bus**

**Regulated**
**Power**

- _Figure 2._

- Position
- Sensors

**Sensor **
**Board**

- Sensor Readout Board

- Pre-Amps
- (8)

- Readout
- Control
- FPGA

- To RAM

- To/From  CPU

- Buffer
- (FIFO)

- 13:1
- MUX
- (digital)

- 8:1
- MUX
- (Analog)

- A/D, MUXs, FIFO Control

**(1 Sensor Readout Board per Free Flyer)**

- _Figure 3._

- A/D
- (1)

- Linear
- Encoders
- (12)

- 8

- Tip/Tilt
- Sensors
- (8)

- 12:1
- MUX
- (digital)

- 12

## Power Board Load

- _Calculations:_
- CPU Board                    =    6 Watts
- H/K & Thermal Board    =    4 Watts
- Sensor Board                =    4 Watts
- Mech Drive Board         =    4 Watts
- Aperture Motors            =    1 Watts each (no simultaneous operation)
- Actuators                       =   1 Watts each (no simultaneous operation)
- Total Conditioned Power = 20 Watts
- Assume Converter Efficiency of ~ 70%
- => Power Board Dissipation = (20/0.7) – 20 =  8.6 Watts

## Electronics Box Power Summary

| Main Electronics Box | Avg. Power |
| --- | --- |
| CPU Board | 6 Watts |
| H/K & Thermal Control Board | 4 Watts |
| Mechanism Drive Board | 4 Watts |
| Sensor Readout Board | 4 Watts |
| Power Supply Board |   8.6 Watts |
| Box Total:   | 26.6 Watts |

## Main Electronics Box Summary

- _Figure 4._

**CPU Board (6W)**

**Total: ~ 26.6 Watts  (avg.)**

**Power Board (8.6W)**

**H/K & Thermal (4W)**

- 7 in
- (17.5 cm)

- 10 in
- (25 cm)

- 8 in
- (20 cm)

- 6 in
- (15 cm)

**Estimated Mass ~ 7 Kg**
**Estimated Power ~ 26.6 Watts (Avg.) Estimated Size ~ (25 x 15 x 17.5) cm.**

- _Main Electronics Box_

**Sensor Board (4W)**

- 6 in
- (15 cm)

**Mech Drive Board (4W)**

## Instrument Power Summary

- _Spacecraft Power Bus Requirement_

| End Items | Avg. Power |
| --- | --- |
| 1 Main Electronics Box |     26.6 Watts |
| Actuators @ 1 Watt each |     1 Watts |
| Drive Motors @ 1 Watt each |  1 Watt |
| Heaters |  25 Watts |
| Instrument Total:   |     53.6 Watts |

## Cost Estimate

*   **(Includes Design, Parts, Fabrication, Test, & ETU)*

## Conclusion

-    circuit boards. No science data on the Free-Flyers and the
-    Hub spacecraft. All Sensor Data and Housekeeping Data
-    is passed to the spacecraft via the 1553 bus.
-   Design could possibly be further optimized by moving
-    CPU functions to the spacecraft side of the bus and
-    utilize the FPGA for the instrument control functions.
-   Packaging could possibly be reduced by combining the
-    actuator drive board with the sensor readout board at the
-    expense of drive circuitry redundancy.
-    _Example:_  A single drive circuit (with one backup) could
-    be multiplexed to each of the actuators given non-
-    simultaneous operation.

## Backup Slides

- (Electrical Design Estimates)

## Processor Board

**CPU**
- (RAD 6000)

- Startup ROM

- EEPROM Memory
- (Thermal control logic)

- Ethernet I/F

- 1553 I/F

- 1553 I/F

- RAM

- Time Stamp
- Function

- S/C 1pps

- S/W Dev.

- _Figure 5._

## Mechanism Drive Circuit

- Drive Cmd

- From
- Processor

- motor

- Open/close
- detection

- HK
- Mux

- +

- -

- To H/K
- Board

- Actuator Current

- Actuator Voltage

- _Figure 6._

- Aperture door

## Thermal Control circuit

- _Figure 7._

- DAC

- HK
- Mux

- VRef

- ISource

- V+

- Heater Current

- Heater Voltage

- Tsensor Voltage

- Tsensor Current

- +

- -

- From
- Processor

- To
- Central HK

- Heater

- Tsensor

- (1 of n circuits shown)

- From
- Processor

## HouseKeeping Circuits

**16-ch**
- AD506

- .
- .
- .

**A/D **
**Conv.**
- AD 1672

- To Controller Board

- Power
- Temp
- ...

**H/K**
**FIFO**

- +

- -

- +

- -

- VRef

- ISource

- Tsensor Voltage

- Tsensor Current

- Mux

- Mux

- V+

- V-

- (1 of n temp sensors)

- _Figure 8._

- I+