Board Layout

DDR3 RAM

96 Pin Ball Grid Array (BGA) package
A33-OLinuXion Top layer
CK/!CK: 0.2mm
addr[0:15], !WE, !CS, !RST, DBA[0:2], ODT, !CKE, CAS, RAS: 3mm
DQ[0:7]: 1.27mm
DQ[8:15]: 1.27mm

Power Supplies

Max efficiency for an LDO
Buck SMPS
Hot loop
Power Distribution Layer

Bill of Materials Generation

The Build

Bare Bords
Pasted Boards
Pre-Reflowed Bords
Finished Boards!

Bringup

The Great Divide

Pros of “two board system”

  • You can rev each board individually. If you want to switch regulators on the power board and you have the inventory of the compute board, you don’t have to discard the compute boards.
  • Noise isolation, you’re physically moving all the switching regulators away from the sensitive electronics.
  • Different board manufacturing capabilities. I might choose 1oz copper for the compute and 2oz for the power. Compute might need 4 layers while the power only needs two layers.
  • Vertical space gain. There is a lot of horizontal board space taken by the BGA, RAM, SD card and radios. However, there is very little vertical space required. By stacking two boards, I’ve doubled the horizontal space.

Cons

  • Cost. It’s more expensive to build two boards instead of one.
  • Signal Integrity. If you have high-speed signals running between boards, you have to worry about the SI of the board-to-board connector.
  • Assembly time. Gotta plug em together, yo.
  • Mechanical design and interface.
RTL8188CUS Step File
RTL8188CUS Symbol
CUI’s PBO-15C-5
CUI’s Recommended Design

The Mech

Low Cost all Charger

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Building things.

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