In-situ cable unplug detector operating during normal signaling mode

摘要

An in-situ unplug detector circuit detects when a cable is disconnected or unplugged. Detection does not have to wait for normal signaling to pause, such at the end of a frame or timeout. Instead, detection occurs during normal signaling. When the cable is disconnected, the transmitter no longer drives the load at the far end of the cable, and thus can drive the near end to a higher high voltage and to a lower low voltage. The increased voltage swing is detected by a detector at the near end that amplifies the transmitter output to the cable. A fast detector has a higher bandwidth and faster response time than a slow detector, and generates a fast detect signal that crosses over a slow detect signal. When the cable is disconnected, the fast detect signal again crosses over the slow detect signal, and decision logic activates an unplug signal.

主权项

1. A circuit for detecting a disconnect condition for a cable coupled between a transmitter and a receiver, comprising:
first circuitry configured to receive a transmitted signal transmitted on the cable by the transmitter, and to generate a first signal that is representative of the transmitted signal; second circuitry configured to receive the transmitted signal and to generate a second signal that is representative of the transmitted signal, wherein the second circuitry is configured to respond faster than the first circuitry to changes in the transmitted signal; and third circuitry configured to receive the first and second signals and to generate a third signal therefrom that is representative of the disconnect condition.