National Instruments NI USB-621x manual 26

Chapter 3 Connector Information

+5 V Power as an Input

If you have high current loads for the digital outputs to drive, you can exceed the 50 mA internal limit by connecting an external +5 V power source to the +5 V terminals. These terminals are protected against undervoltage and overvoltage, and they have a 350 mA self-resetting fuse to protect them from short circuit conditions. If your USB-621xdevice has more than one +5 V terminal, you can connect the external power supply to one terminal and use the other as a power source.

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