USB2.0 PHY IC
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.
T0
T1
T2
T3
T4
time
SUSPENDN
XCVRSELECT
TERMSELECT
DP/DM
Last
Activity
Soft SE0
'J' State
Device is suspended
Figure 8.2 Suspend Timing Behavior (HS Mode)
Table 8.5 Suspend Timing Values (HS Mode)
DESCRIPTION
TIMING
PARAMETER
VALUE
0 (reference)
HS Reset T0
End of last bus activity, signaling either a reset or
a SUSPEND.
T1
T2
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
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
T4
The earliest time where a device can issue
Resume signaling.
HS Reset T0 + 5ms
HS Reset T0 + 10ms
The latest time that a device must actually be
suspended, drawing no more than the suspend
current from the bus.
8.7
HS Detection Handshake
The High Speed Detection Handshake process is entered from one of three states: suspend, active
FS or active HS. The downstream facing port asserting an SE0 state on the bus initiates the HS
Detection Handshake. Depending on the initial state, an SE0 condition can be asserted from 0 to 4
ms before initiating the HS Detection Handshake. These states are described in the USB2.0
specification.
There are three ways in which a device may enter the HS Handshake Detection process:
SMSC GT3200, SMSC USB3250
Revision 1.3 (10-05-04)
DATA3S0HEET
SMSC [ SMSC CORPORATION ]
