USB port issues

Good day folks,

Background: I am currently using the FriendlyARM Mini2440 board with a
contactless cardreader (ACR 112). I am reading the cards using the
cardreader API in the C language.

Problem: At times, sometimes frequently, sometimes less frequently the
external cardreader seems to freeze up completely. This causes my
application to freeze aswell. (unplugging and replugging it works). My
first guess is that this might be a USB power issue. The cardreader pulls
100mA-200mA of current. I have read that the Raspberry Pi has a USB port
that can only supply 150mA of current. I could however not find any speccs
for the FriendlyARM Mini2440.

Question: Can anybody tell me what the max current of the USB port on this
board is? Also any feedback and guesses on what might be the issue will be
appreciated.

Thanks!

The USB supply comes straight from the power supply that you power the
board with.  So, the max current is limited by the current rating of the
PCB tracks and whatever is left over from the power supply after running
the board.

Be aware that some plug-paks are marginal in the current department. 
Monitor the actual supply voltage with a DVM while the screen is enabled.
If the voltage gets down around 4.7 to 4.8Volts the unit can just stop
working.

Also, the power socket or more likely the plugs that fit into it are very
critical in their actual dimensions.  I had to get 2 or 3 different brands
of the "same" plug to find ones that fit tight enough not to cause screen
flicker.

Good luck!