USB5744SLASH2G datasheet(31/51 Pages) MICROCHIP

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DS00001855K-page 31

USB5744

9.0

COMPLIANCE UPDATE

In order to be USB-IF certified (TID 330000076), the USB5744 supports the USB 3.2 Engineering Change Notices

(ECNs) included in the Universal Serial Bus Revision 3.2 Specification. This allows the latest revision of the USB5744

to be certified in compliance with USB-IF logo testing for the new USB Type-C® industry initiative. The following com-

pliance updates are supported:

• Pending Header Packet (HP) Timer (TD7.9, TD7.11, TD7.26)

• Power Management (PM) Timer (TD7.18, TD7.20, TD7.23)

• Unacknowledged Connect and Remote Wake Test Failure (TD10.25)

These USB 3.2 ECNs can be found as part of the Universal Serial Bus Revision 3.2 Specification zip file, which can be

downloaded from the USB developers website (http://www.usb.org/developers/docs/).

9.1

Pending Header Packet (HP) Timer (TD7.9, TD7.11, TD7.26)

A turn around time is defined between the communication of a Host and Device (Link Partners) for an acknowledgment

of a USB connection. The time is budgeted between a number of steps (Transmit/Receive data path of the initiator, the

delay in the cable, and the response time of the responder). If the time is exceeded, no USB communication is initiated.

The ECN calls to relax the timing from 3us to 10us at the link and PHY layers to allow for an extended propagation delay

to account for the usage of active cables and retimers in new SuperSpeed Plus designs.

Impact to Legacy Systems:

• A new host with a retimer connected to an active cable AND a legacy device

• A legacy host connected to an active cable and a new device with or without a retimer

9.2

Power Management (PM) Timer (TD7.18, TD7.20, TD7.23)

There are three timers for link power management: PM_LC_TIMER, PM_ENTRY_TIMER, and Ux_EXIT_TIMER. The

PM_LC_TIMER is used for a port initiating an entry request to a low power link state. The PM_ENTRY_TIMER is used

for a port accepting the entry request to a low power link state. Ux_EXIT_TIMER is used for a port to initiate the exit

from U1 or U2 to a low power state.

The ECN calls to increase the maximum timeout values to accommodate for the new connectivity models with retimers

and active cables beyond the standard USB-IF transmission lengths.

Impact to Legacy Systems:

• No impact to USB 3.0 or early USB 3.2 ecosystems

9.3

Unacknowledged Connect and Remote Wake Test Failure (TD10.25)

If a USB3 port with a connected device is placed into Suspend and RemoteWake is set but the RemoteWake mask

(C_PORT_CONNECTION bit) has not been cleared, the USB3 hub will automatically issue a wake up signal to the host.

In legacy systems, if a USB3 port with a connected device was placed into Suspend and RemoteWake is set without

the mask bit being cleared, the USB3 hub would NOT issue a wake up signal to the host.

Impact to Legacy Systems:

• No impact – with the new implementation, a remote wake is automatically initiated if the mask bit is not set. In

older systems the remote wake may or may not have been executed.

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