Power question USB Hub host

I brought a MPD218 that work's when connected directly on my MBP, but not on my iPad...

When I try to connect it via iCA4+ it powers, but isn't recognized neither by the MBP or iPad. If I put a powered usb hub in the chain, it works well...

Question: doesn't iCA4+ provides the same energy of MBP? I always though that and, if so, why would it start on MBP and not with iCA4+?


  • The iCA4+ provides the standard USB2 power spec of 500mA at 5v. The MBP provides an extended power spec (probably because it's USB3).

    In the USB 1.0 and 2.0 specs, a standard downstream port is capable of delivering up to 500mA (0.5A); with USB 3.0, it moves up to 900mA (0.9A). The charging downstream and dedicated charging ports provide up to 1,500mA (1.5A).

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