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X14 Power Bricks
IMAGE OF PCB, potentially including its place on the relevant ROV
| PCB Summary | |
|---|---|
| Vehicle | X14, ROV Sub-Optimal |
| Contributors | Yusuf Jarada |
| Predecessors | X13 Power Bricks |
| Success? | {} |
Architecture Link
SID Link
REPO Link
The primary function is to convert 48V at 25A to 12V at 50A
- The board connects to the Powers bricks (Part Number: Q48SC12050) and the Distribution board
- The board connects to 4 blades (12V,12GND, 48V, 48GND) and 5 pins in the middle for data (see below for more info)
What priorities did you have in your design? What design considerations did you have? What methodologies did you follow? (routing a differential pair, keeping something separate for isolation, etc)
- Needed to keep the capacitors and any other big power polygon in isolation from other connections so that it would not short and cause an accident.
- The general trend of this board was to make everything as thermodynamically efficient as possible which means making the pads very large so that power can flow efficiently with minimal resistance.
There were not many changes from last year's board, only that we are using a new connector so the wiring and polygons needed to be slightly different to accommodate for it.
- The board outline was determined by the dimensions we had for the box. We wanted to be able to make the board as big as possible in the space given to optimize power flow. We also wanted to have the input voltage region separate from the output voltage region and the connector in the middle so it could both send and receive different voltages. The bricks needed to sit flush with the bottom of the box and the board sits directly on top of the bricks.
- The board needed to be just large enough to house the connectors and since we used a new connector to the distribution board we made the bricks board slightly wider for this year.
- The bricks were placed under the board so they did not affect the width or depth of the board.
- The Distribution board was directly on top of the Bricks Board, so the connector was placed in the center of the Bricks board to make the connection stable and centered
Bricks datasheet: (https://www.mouser.com/datasheet/2/632/DS_Q48SC12050-611323.pdf)
- Outputs 12V at 50A per brick. Shouldn't expect all 100A with 2 bricks in parallel, manufacturer says derate to 90% when parallelizing
- Data pins: (hardware is rated for 100 megabits)
- ON/OFF
- Data
- CLK
- C2
- ALERT
Why did you pick certain components for your board? (If you don't know the answer/were told, now is a great time to ask)
- https://www.samtec.com/products/pesc (connector)
- https://suddendocs.samtec.com/testreports/tc0838--1964_powerpin_report_rev_2_pwr.pdf (power tests)
- https://suddendocs.samtec.com/testreports/tc0838--1964_signalpin_report_rev_3_pwr.pdf (signal tests)
- The connector could handle the current draw and had enough data lines for all communication needs. Each blade was able to handle 50A with not much of a temperature increase. See power tests above.
- https://www.digikey.com/en/products/detail/delta-electronics/Q48SC12050NRDH/6133805
The connection with the Distribution Board was tricky as lining up the connectors upside down was a bit of a challenge.
Mechanically everything went fine since the board was more or less flush with the bottom of the box.
This board needs a lot of space for it to function in design. The power needs room to flow from one pad to another and the isolation needs to be taken into consideration as to not risk shorting the board in any way. When making this board, try to consider thermals as much as possible since it is the main high current component on the board.
- The connector from the brick board to distribution was flipped so we needed to put on the bricks backward in assembly. We should have made sure that the connector pins were mirrored properly when the board connects to other boards.
- The new connector we used this year was slightly wider so we made the board wider to compensate for it. However I forgot to recenter the board on the new longer connector.
- I would switch the connectors so that they are lined up properly. The design is fixed now, but in the future make sure to communicate a lot with the person designing the board you're connecting to know the difference between a rotation and reflection of a connector when you flip the board over to connect.
- I would increase Isolation values on the polygons so the through-holes are more isolated from the metal
- I might redo the entire layout to make it more optimal. The Polygons connecting power are weirdly shaped on some parts of the board so making the layout slightly better so that polygons can be more uniform is a place
- I would recenter the connectors on the board so the board and bricks fit better into the box
See X13 wiki for brick calculations. All other calculations were taken from data sheets.
Any addition links if relevant
- Any fun side details
Search keywords.
The Power Bricks Board is used to convert power from an input of 48V at 12A to 12V at 25A. The board takes its input from the Distribution Board and passes the power to the bricks where it is converted to 12V and then returned to the board along with 5 data lines. These signals are then sent back to the Distribution Board. The main change for this generation is the new connector which allows the board to be smaller and simpler. The connector connects all power lines through 4 blades and 5 data pins to the distribution board. There are two Power Bricks Boards that work in tandem to provide 12 V at a total of 50 A.
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