The max.power that manufactures specify for devices might not be very accurate. Also, the device might not be able to hit its specified peak current consumption under "normal" working conditions. So, there's no simple answer to this question, imho.
All we know is that OTG port on pxa270-based Z's would max. out @ approx. 200mA, but that could be changed by simply replacing the controlling resistor,
-albertr