A Universal Serial Bus (USB) controller includes a USB transceiver to detect a high-speed (HS) disconnect between the USB controller and a device connected to it. The USB transceiver includes a reference-voltage generation circuit, a HS current driver, first and second comparators, and a multiplexer. The reference-voltage generation circuit generates HS disconnect and transmitter reference-voltage signals that have a constant voltage difference. The first comparator receives DP and DM signals that correspond to a HS Start of Frame (SOF) packet during HS disconnect detection, and generates a control voltage. The multiplexer outputs at least one of the DP and DM signals based on the logic state of the control voltage. The second comparator receives the selected signal and the HS disconnect reference-voltage signal, and outputs a HS disconnect output voltage signal when the selected signal is greater than the HS disconnect reference-voltage signal.