MEP EP#14: Discrepant Diodes

Parker Dillmann |   |  Atmel, Crowd Supply, Diodes, Engineering, FX Dev Board, House Parts, MEP, Podcast, SSPS, USB 3.0

MacroFab Engineering Podcast


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Parker Dillmann
Stephen Kraig


Figure 1: SSPS front panel layout. Traces to come soon.

Figure 2: Inconsistencies in the LTST-C171CKT datasheets.

Podcast Notes

  • Stephen is still working on customer fixtures but managed to get some progress on the FX Development Board done. Stephen has been working on the documentation to get the Crowd Supply fundraising going. He still needs to prototype the enclosure.
  • Parker has been working on the SSPS front panel design. See Figure 1.
  • Parker is going to use Omron’s B3W-9000-RG2C illuminated switches because it has a Red and Green LED and allows for custom key caps via printable transparencies.
  • The Bourns’ PEL12T-4226F-S1024 RGB Encoder will function to adjust the power on the supply. This is a 2-bit encoder with a clear shaft that is illuminated with a RGB LED.
  • Instead of 74HC595s, Parker is going to use a STP16CP05 LED driver. The IC is a 16-bit constant current sink driver. He chose the TSSOP-24 package because it has a thermal pad to improve the heat dissipation.
  • Parker hasn’t decided on whether to go with a USB 2.0 Type B connector like most industrial devices or go with the new Type C style. He is going to try the TI TPS65982 which is a USB Type C controller and power switch IC. It has a $30 evaluation board, TPS65982-EVM.
  • Operations at MacroFab found a datasheet inconsistency with a Lite-On LED. P/N: LTST-C171CKT which is a house part at MacroFab (MF-LED-0805-RED). Both datasheets are identical except one drawing is anode marked and the other is cathode marked. We checked our stock and the LTST-C171CKT’s are cathode marked.
  • Atmel is removing the full-swing crystal oscillator from their entire MEGA line of IC’s. Parker thinks it is weird that they are changing the tooling for such established MCUs. Here is a Hackaday article about the topic.
  • Interesting topic on the ECE subreddit on “In your opinion, what makes someone a “bad engineer?”. Parker and Stephen talk about engineering ethics.
  • Parker thinks this video of a power transformer starting up is an awesome sound effect. This gets Parker talking about the best sound effect ever, which is the tractor beam shut down sound in Star Wars, which rivals the hyper drive malfunction sound in Star Wars. Stephen wants to build a replica of the Death Star laser firing lever.

Special thanks to whixr over at Tymkrs for the intro and outro theme!