Below is a circuit I'm making. A 24 VDC PSU (VCC) goes through this switching regulator and outputs 5V to power the load. However, the load can also be powered directly by the USB 5V (USBVCC).
Now if the USB is connected but the 24 VDC PSU isn't, I'm getting a ~3.3V reading on the input line of the regulator. Is there a specific name for this? I've been calling this a "voltage back-drive" for now. Also, is this ok for the regulator or will it be damaging in the long run?