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  • EEVblog #357 – USB Supply Power-up Testing

    Posted on September 21st, 2012 EEVblog 13 comments


    Forum Topic HERE
    Some basic power up testing of Dave’s prototype USB power supply.
    With some bonus Murphy’s troubleshooting.
    Thanks to www.pcbzone.net for the PCB

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    13 responses to “EEVblog #357 – USB Supply Power-up Testing” RSS icon

    • Yep, done that before. This is why it pays to have carefully-made and tested libraries of components that you know you can rely on.

      If you tend to make your libraries generic, it can be a bit of a problem since this sort of mistake can creep in when you are placing components. If you make the components in your library type-specific then there’s less chance of error but then you need to edit your library every time you use a slightly different device. I prefer to do it that way, though.

      You could potentially find a different transistor that has the footprint you accidentally designed your board for and use that – assuming it has competible specs.

      • Yeah, I’ve chopped and changed library systems so many times, it’s just silly. No one coherent system, and its hard when you work on projects on different machines at work or home etc.
        I’ve never really done enough of my own personal PCB’s in the one place to maintain a decent cohesive library.

        • It would be fantastic to have a component library system that worked across different pieces of ECAD software. At the moment I’m constantly having to add components to Altium (which I use for work) that I already have in my EAGLE library (which I use at home) and vice versa. It’s possible to transfer components between them (at least from EAGLE to Altium) but the process is a bit involved.

          It may be worth spending some time going through and checking/cleaning up your library(s). I’ve done that in the past and it paid off. Takes up precious time but reduces the chance of mistakes.

    • Blow it out your bum.. lol

    • I’m waiting for some FT231X with delivery in October aswell. Darn FTDI!

    • Have been waiting…this power supply going to be a beauty and a WINNER.

    • Is the purpose of this PCB to charge a 4.2VDC LiPo battery from any USB port?

    • This power supply style is such a great idea… I’m really happy that you ended up with an lcd for the display after exploring all the other possibilities. Maybe the other were cheaper but lcd is the best way to go… Do you have any idea about how much are you going to price it ? Because I’m already interested in buying you one. Do you ship internationally ? (Argentina) I can even buy a pre-sale if that helps you fund the design efforts.

    • Dave

      Have you seen the pre-biased transistors that are available? Such as the mouser part 652-CR0603-JW-102ELF?

      About the same price as a standard transistor, and with built in resistors you get a reduction of parts on your board. Very hand when chasing space…

      In a SOT-23 package too, and if you like I can share working altium libs :)

    • Gak

      Copy and paste error – meant 863-MMUN2211LT1

    • Ha ha! :p
      But, yes, we have all done that before.
      My whole class, the 3rd year of a bachelor degree, did an audio amplifier project with discrete transistors, and I don’t think a single board came out without a component layout issue like that. Doh! >_<
      Nice video BTW :D

    • Awesome video Dave! I feel like everyone needs more content like this, to be able to see someone diagnosing issues on a board and communicating that thought process. That may have been a really simple fix but I’m sure for most of us it would have taken a lot longer to find.

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