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Suitable for Apple devices?

  • thunder45 Thursday, January 9, 2014 3:33 AM Reply
    Hi Desolder and Ohm711
    Let me see if I got you guys right: it can quickly charge an android tablet and some of the new apple devices, right?

    I´m looking for a fast charger for my PIPO U8 tablet. Having the ability to fast charge my iPad Mini as well would be awesome.

    By the way, did you confirm the 3A on a single port even with load applied to it?

    Best regards
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  • desolder Top 10 Forum Poster Thursday, January 9, 2014 4:33 AM Reply
    For newer apple devices, yes it will fast charge, up to 2.1A. Older apple devices won't recognize the 2.1A voltages, so they may refuse to charge. Swapping around the resistors like Ohm711 did will fix this problem for those older devices, but then you lose the ability to charge at 2.1A. One way to work around this is to use different sets of D-/D+ voltages. I noticed that the PCB has TWO sets of voltage dividing resistors. The bottom two ports in Ohm711's photo can be configured differently from the top two. So you could configure say two of the ports for 2.1A compatibility, and the other three for 1A compatibility (or whatever combination you need).

    For android devices, fast charging is a MAYBE. From what I understand, the standard for android is to short the D- and D+ lines to enable fast charging. However this charger does not implement that scheme. It uses the apple scheme. So perhaps some android vendors decided to also accept the apple scheme. It all depends on the android device. If you have a mix of android and apple devices, then hacking is again probably your best option. Say use the shorted D-/D+ scheme for some ports, then configure the other ports with an apple scheme.
    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

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  • thunder45 Monday, January 13, 2014 11:07 PM Reply
    Thank you very much Desolder! That is really helpful.
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  • eatatjoes10 Tuesday, January 28, 2014 1:45 AM Reply
    Hi desolder and thunder45,
    from the second picture I assume the regulator could be a L78S05, that is able to handle 2A (with good heatsink), and 3A only for "short circuit". So this charger is capable for 3A for only a very short time.
    From the datasheet:
    http://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDEQFjAA&url=http%3A%2F%2Fwww.st.com%2Fweb%2Fen%2Fresource%2Ftechnical%2Fdocument%2Fdatasheet%2FCD00000449.pdf&ei=45nmUrqjDabc4wSR44HwCw&usg=AFQjCNGp8xOkDSgnHOBeGgjYjVJ1XJRPMA&sig2=DQaa8fSuwuVDT7Tcjd-X-A&bvm=bv.59930103,d.bGE&cad=rja
    "If adequate heat sinking is provided, they can deliver over 2A output current"
    That small heatsink is not "adequate", and it is inside a closed housing (I can not see any openings on the DX-pictures).
    I assume, even 2A for a longer time will make the L78S05 shut down (due to the thermal protection)
    experienced toddler
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  • desolder Top 10 Forum Poster Tuesday, January 28, 2014 2:31 AM Reply
    eatatjoes10, this is a switch mode power supply, so it doesn't use the classic 7805 regulator. The heatsinked device you see is the primary switching transistor, typically a low loss MOSFET. It dissipates very little power because it is not operated in linear mode. It is either fully on or fully off.
    What's up with the scrubbed LED driver IC markings?
    What are they trying to hide?

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  • eatatjoes10 Tuesday, January 28, 2014 4:17 AM Reply
    Hi desolder,
    thank you, for clearing this up, you're still the best.
    I saw it is a switching power supply, but didn't see the transistor. It didn't come to my mind, that it's "my 78S05", that I was looking for.
    There are so many "power modules" on DX, using a 78xx or 78Sxx, and they are declared to handle the "absolute maximum rating (with proper heatsinking)" from the datasheets, but lacking a proper heatsink, that I was doubtful about this.
    I want to order this for a friend, and he needs more than 2A, so it should work for his needs...
    experienced toddler
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