Low power embedded USB2 (eUSB2) repeater

1 . A method of operating an embedded universal serial bus (eUSB) repeater, comprising:

holding an eUSB receiver and a universal serial bus (USB) transmitter in active states while holding a USB receiver and an eUSB transmitter in standby states, wherein the USB transmitter couples to the eUSB receiver so as to receive downstream packets from the eUSB receiver, and wherein the eUSB transmitter couples to the USB receiver so as to receive upstream packets from the USB receiver;

receiving by the eUSB receiver a token packet indicative of transmission of a first downstream packet; and

transitioning the USB receiver and the eUSB transmitter from the standby states to the active states responsive to receiving the token packet.

2 . The method of claim 1 , further comprising transmitting the token packet by the USB transmitter.

3 . The method of claim 2 , further comprising:

receiving by the eUSB receiver the first downstream packet or receiving by the USB receiver an upstream packet within a first timeout period after receiving the token packet; and

transmitting the first downstream packet by the USB transmitter or transmitting the upstream packet by the eUSB transmitter.

4 . The method of claim 2 , further comprising transitioning the USB receiver and the eUSB transmitter from the active states to the standby states if no packet is received within a first timeout period after receiving the token packet.

5 . The method of claim 3 , further comprising transitioning the USB receiver and the eUSB transmitter from the active states to the standby states if no packet is received within the first timeout period.

6 . The method of claim 3 , further comprising holding the USB receiver and the eUSB transmitter in the active states if a packet is received within the first timeout period.

7 . The method of claim 3 , further comprising transitioning the USB receiver and the eUSB transmitter from the active states to the standby states if a last packet transmitted was an upstream packet.

8 . The method of claim 1 , wherein the eUSB repeater is a host-side repeater.

9 . The method of claim 1 , further comprising:

holding a high-speed disconnect circuit in a standby state; and

transitioning the high-speed disconnect circuit from the standby state to an active state responsive to receiving the token packet.

10 . The method of claim 1 , further comprising:

holding a USB squelch circuit in a standby state; and

transitioning the USB squelch circuit from the standby state to an active state responsive to receiving the token packet.

11 . The method of claim 10 , further comprising:

holding an eUSB loss of signal (LOS) detection circuit in the standby state; and

transitioning the eUSB LOS detection circuit from the standby state to the active state in response to detecting the first downstream packet by an eUSB squelch circuit.

12 . A method of operating an embedded universal serial bus (eUSB) repeater, comprising:

activating a universal serial bus (USB) receiver and an eUSB transmitter, wherein the eUSB transmitter couples to the USB receiver so as to receive downstream packets from the USB receiver;

receiving, by the USB receiver, a token packet indicative of transmission of a first downstream packet; and

transitioning a USB transmitter and an eUSB receiver from a standby state to an active state responsive to receiving the token packet, wherein the USB transmitter couples to the eUSB receiver so as to receive upstream packets from the eUSB receiver.

13 . The method of claim 12 , further comprising transmitting the token packet by the eUSB transmitter.

14 . The method of claim 13 , further comprising:

receiving by the USB receiver a second downstream packet or receiving by the eUSB receiver an upstream packet within a first timeout period after receiving the token packet; and

transmitting the second downstream packet by the eUSB transmitter or transmitting the upstream packet by the USB transmitter.

15 . The method of claim 14 , further comprising transitioning the eUSB receiver and the USB transmitter from the active states to the standby states if no packet is received within the first timeout period.

16 . The method of claim 12 , further comprising transitioning the eUSB receiver and the USB transmitter from the active states to the standby states if no packet is received within a first timeout period.

17 . The method of claim 14 , further comprising holding the eUSB receiver and the USB transmitter in the active states if a packet is received within the first timeout period.

18 . The method of claim 12 , wherein the eUSB repeater is a peripheral-side repeater.

19 . The method of claim 12 , further comprising:

holding an eUSB squelch circuit in the active state;

detecting by the eUSB squelch circuit an upstream packet; and

transitioning the USB transmitter and the eUSB receiver from the standby states to the active states responsive to the detection of the upstream packet.

20 . The method of claim 19 , comprising holding the eUSB receiver and the USB transmitter in the active states.

21 . The method of claim 12 , further comprising holding a high-speed disconnect circuit in a standby state.

22 . The method of claim 12 , further comprising:

holding an eUSB squelch circuit in the standby state; and

transitioning the eUSB squelch circuit from the standby state to the active state responsive to the token packet.

23 . The method of claim 12 , further comprising:

holding an eUSB loss of signal (LOS) detection circuit in the standby state; and

transitioning the eUSB LOS detection circuit from the standby state to the active state responsive to a detection of an upstream packet by an eUSB squelch circuit.

24 . A method of operating a repeater having a first input/output (I/O), a second I/O, a first transmitter, a second transmitter, a first receiver, and a second receiver, the method comprising:

holding the first receiver and the first transmitter in active states while holding second receiver and the second transmitter in standby states;

receiving by the first receiver a token packet indicative of transmission of a downstream packet;

transitioning the second receiver and the second transmitter from the standby states to the active states responsive to receiving the token packet;

receiving by the first receiver the downstream packet or receiving by the second receiver an upstream packet within a first timeout period after receiving the token packet; and

transmitting the downstream packet by the first transmitter or transmitting the upstream packet by the second transmitter.

25 . The method of claim 24 , further comprising transitioning the second receiver and the second transmitter from the active states to the standby states if no packet is received within a first timeout period after receiving the token packet.

26 . The method of claim 24 , wherein the repeater is a host-side repeater.

27 . A method of operating an embedded USB2 (eUSB2) repeater, comprising:

holding a USB 2.0 receiver and an eUSB2 transmitter in active states while holding an eUSB2 receiver and a USB 2.0 transmitter in standby states;

receiving by the USB 2.0 receiver a token packet indicative of transmission of a first downstream packet;

transitioning the USB 2.0 transmitter and the eUSB2 receiver from the standby states to the active states responsive to the token packet;

receiving by the USB 2.0 receiver a second downstream packet or receiving by the eUSB2 receiver an upstream packet within a first timeout period after receiving the token packet;

transmitting the second downstream packet by the eUSB2 transmitter or transmitting the upstream packet by the USB 2.0 transmitter; and transitioning the eUSB2 receiver and the USB 2.0 transmitter from the active states to the standby states if no packet is received within the first timeout period.

28 . The method of claim 27 , wherein the eUSB2 repeater is a peripheral-side repeater.