SMSC USB3280 - Manual (Page 31)

Hi-Speed USB Device PHY with UTMI Interface
Datasheet
SMSC USB3280 31 Revision 1.5 (11-15-07)
DATASHEET
8.6 Suspend Detection
If a HS device detects SE0 asserted on the bus for more than 3ms (T1), it reverts to FS mode. This
enables the FS pull-up on the DP line in an attempt to assert a continuous FS J state on the bus. The
SIE must then check LINESTATE for the J condition. If J is asserted at time T2, then the upstream
port is asserting a soft SE0 and the USB is in a J state indicating a suspend condition. By time T4
the device must be fully suspended.
Figure 8.2 Suspend Timing Behavior (HS Mode)
Table 8.5 Suspend Timing Values (HS Mode)
TIMING
PARAMETER DESCRIPTION VALUE
HS Reset T0 End of last bus activity, signaling either a reset
or a SUSPEND. 0 (reference)
T1 The time at which the device must place itself
in FS mode after bus activity stops. HS Reset T0 + 3. 0ms < T1 < HS Reset T0
+ 3.125ms
T2 SIE samples LINESTATE. If LINESTATE = 'J',
then the initial SE0 on the bus (T0 - T1) had
been due to a Suspend state and the SIE
remains in HS mode. T1 + 100 µs < T2 <
T1 + 875µs
T3 The earliest time where a device can issue
Resume signaling. HS Reset T0 + 5ms
T4 The latest time that a device must actually be
suspended, drawing no more than the
suspend current from the bus. HS Reset T0 + 10ms