Active optical cable (AOC) and a method and apparatus for performing power management in the AOC
View Patent ↗An active optical cable is provided that incorporates a power management solution. The AOC has plugs that are configured to mate with respective USB sockets. The AOC is used to interconnect a USB host with a USB device. To the USB host and to the USB device, the AOC appears to be a standard USB electrical cable. Each of the plugs of the AOC has an optical-to-electrical and an electrical-to-optical (OE/EO) conversion module that converts electrical USB signals output from the USB host or USB device into optical signals and converts optical signals carried on the optical fibers of the AOC into electrical USB signals. The plugs include controllers that monitor certain conditions of the AOC and that select the power levels to be used in the plugs based on detected conditions.
1. An active optical cable (AOC) comprising:
an optical fiber cable having a proximal end, a distal end, at least a first transmit optical fiber having proximal and distal ends, and at least a first receive optical fiber having proximal and distal ends;
a first plug secured to the proximal end of the optical fiber cable, the first plug having a first plug housing configured to mate with a Universal Serial Bus (USB) socket, a first optical-to-electrical and electrical-to-optical (OE/EO) conversion module disposed in the first plug housing, first electrical power and signal (EPS) detection circuitry disposed in the first plug housing, and a first controller disposed in the first plug housing and electrically coupled to the EPS detection circuitry, wherein the OE/EO conversion module is optically coupled to the proximal ends of the first transmit and receive optical fibers and is electrically coupled to the EPS detection circuitry, and wherein the first EPS circuitry is electrically coupled to the first controller for outputting output signals to the first controller, the first OE/EO conversion module comprising at least a first OE conversion element for converting optical signals into electrical signals and a first EO conversion element for converting electrical signals into optical signals, and wherein the first controller is configured to perform a power management algorithm that processes the output signals from the EPS circuitry to determine which of a plurality of different predetermined signal types is currently being detected by the EPS detection circuitry, and wherein the first controller causes the first plug to be placed in a selected power state of a first set of predetermined power states based on which of the predetermined signal types is currently being detected; and
a second plug secured to the distal end of the optical fiber cable, the second plug having a second plug housing configured to mate with a USB socket, a second OE/EO conversion module disposed in the second plug housing, second detection circuitry disposed in the second plug housing, and a second controller disposed in the second module housing and electrically coupled to the second EPS detection circuitry, the second OE/EO conversion module being optically coupled to the distal ends of the first transmit and receive optical fibers and being electrically coupled to the second EPS detection circuitry, and wherein the second EPS circuitry is electrically coupled to the second controller for outputting output signals to the second controller, the second OE/EO conversion module comprising at least a second OE conversion element for converting optical signals into electrical signals and a second EO conversion element for converting electrical signals into optical signals, and wherein the second controller is configured to perform a second power management algorithm that processes the output signals from the second EPS circuitry to determined which of the different predetermined signal types is currently being detected by the second EPS detection circuitry, and wherein the second controller causes the second plug to be placed in a selected power state of a second set of predetermined power states based on which of the predetermined signal types is currently being detected by the second EPS circuitry.
2. The AOC of claim 1 , wherein the first and second sets of predetermined power states include at least a SLEEP state and an ACTIVE state, wherein when the first plug is in the SLEEP state, a lowest level of electrical power is used by the first plug, and wherein when the first plug is in the ACTIVE state, a highest level of electrical power is used by the first plug, wherein when the second plug is in the SLEEP state, a lowest level of electrical power is used by the second plug, and wherein when the second plug is in the ACTIVE state, a highest level of electrical power is used by the second plug.
3. The AOC of claim 2 , wherein the first and second sets of predetermined power states further include at least a WAIT state and a Low Frequency Periodic Signaling (LFPS) state, and wherein in the WAIT state, a level of electrical power is used by the first and second plugs that is higher than the lowest level of electrical power used by the first and second plugs in the SLEEP state and lower than the highest level of electrical power used by the first and second plugs in the ACTIVE state, and wherein in the LFPS state, a level of electrical power is used by the first and second plugs that is higher than the level of electrical power used by the first and second plugs in the WAIT state and lower than the highest level of electrical power used by the first and second plugs in the ACTIVE state.
4. The AOC of claim 3 , wherein the first and second plugs enter the SLEEP state upon being powered on, and wherein if the first controller determines that the first EPS circuitry is currently detecting a first signal type, the first controller determines that the second plug has been plugged into a socket of a USB device, and wherein if the first controller determines that the second plug has been plugged into the socket of the USB device while the first plug is in the SLEEP state, the first controller causes the first plug to exit the SLEEP state and enter the WAIT state.
5. The AOC of claim 4 , wherein if the first controller determines that the first EPS circuitry is currently detecting a second signal type, the first controller determines detecting that the second plug is transmitting LFPS signals to the first plug, and wherein if the first controller determines that the second plug is transmitting LFPS signals to the first plug while the first plug is in the WAIT state, the first controller causes the first plug to exit the WAIT state and enter the LFPS state.
6. The AOC of claim 5 , wherein if the first controller determines that the first EPS circuitry is currently detecting a third signal, the first controller determines that the second plug is transmitting high-speed (HS) data signals to the first plug, and wherein if the first controller determines that the second plug is transmitting HS data signals to the first plug while the first plug is in the LFPS state, the first controller causes the first plug to enter the ACTIVE state.
7. The AOC of claim 3 , wherein the first and second plugs enter the SLEEP state upon being powered on, and wherein if the second controller determines that the second EPS circuitry is currently detecting a first signal type, the second controller determines that the first plug has been plugged into a socket of a USB host, and wherein if the second controller determines that the first plug has been plugged into the socket of the USB host while the second plug is in the SLEEP state, the second controller causes the second plug to exit the SLEEP state and enter the WAIT state.
8. The AOC of claim 7 , wherein if the second controller determines that the second EPS circuitry is currently detecting a second signal type, the second controller determines that the first plug is transmitting LFPS signals to the second plug, and wherein if the second controller determines that the first plug is transmitting LFPS signals to the second plug while the second plug is in the WAIT state, the second controller causes the second plug to exit the WAIT state and enter the LFPS state.
9. The AOC of claim 8 , wherein if the second controller determines that the second EPS circuitry is currently detecting a third signal type, the second controller determines that the first plug is transmitting high-speed (HS) signals to the second plug, and wherein if the second controller determines that the first plug is transmitting HS signals to the second plug while the second plug is in the LFPS state, the second controller causes the second plug to enter the ACTIVE state.