USB3450 Standard Microsystems Corporation, USB3450 Datasheet - Page 37

• Manufacturer Part Number: USB3450
• Description: Hi-speed USB HOST OR Device PHY WITH Utmi+interface
• Manufacturer: Standard Microsystems Corporation

Hi-Speed USB Host or Device PHY With UTMI+ Interface
Datasheet
SMSC USB3450
7.12
PARAMETER
TIMING
T0
T1
T2
T3
T4
Resume signaling always takes place in FS mode (TERMSELECT and XCVRSELECT = FS enabled),
so the behavior for a HS device is identical to that of a FS device. The Link uses the LINESTATE
signals to determine when the USB transitions from the 'J' to the 'K' state and finally to the terminating
FS EOP (SE0 for 1.25us-1.5µs.).
The resume signaling (FS 'K') will be asserted for at least 20ms. At the beginning of this period the
Link may negate SUSPENDN, allowing the transceiver (and its oscillator) to power up and stabilize.
The FS EOP condition is relatively short. Links that simply look for an SE0 condition to exit suspend
mode do not necessarily give the transceiver’s clock generator enough time to stabilize. It is
recommended that all Link implementations key off the 'J' to 'K' transition for exiting suspend mode
(SUSPENDN = 1). And within 1.25µs after the transition to the SE0 state (low-speed EOP) the Link
must enable normal operation, i.e. enter HS or FS mode depending on the mode the device was in
when it was suspended.
Detection of Resume
Internal device event initiating the resume
process
Device asserts FS 'K' on the bus to signal
resume request to downstream port
The device releases FS 'K' on the bus. However
by this time the 'K' state is held by downstream
port.
Downstream port asserts SE0.
Latest time at which a device, which was
previously in HS mode, must restore HS mode
after bus activity stops.
Figure 7.7 Resume Timing Behavior (HS Mode)
Table 7.9 Resume Timing Values (HS Mode)
DESCRIPTION
DATASHEET
37
0 (reference)
T0 < T1 < T0 + 10ms.
T1 + 1.0ms < T2 < T1 + 15ms
T1 + 20ms
T3 + 1.33µs {2 Low-speed bit times}
VALUE
Revision 0.1 (05-11-05)