USB2.0 PHY IC
8.11
Assertion of Resume
In this case, an event internal to the device initiates the resume process. A device with remote wake-
up capability must wait for at least 5ms after the bus is in the idle state before sending the remote
wake-up resume signaling. This allows the hubs to get into their suspend state and prepare for
propagating resume signaling.
The device has 10ms where it can draw a non-suspend current before it must drive resume signaling.
At the beginning of this period the SIE may negate SUSPENDN, allowing the transceiver (and its
oscillator) to power up and stabilize.
Figure 8.7 illustrates the behavior of a device returning to HS mode after being suspended. At T4, a
device that was previously in FS mode would maintain TERMSELECT and XCVRSELECT high.
To generate resume signaling (FS 'K') the device is placed in the "Disable Bit Stuffing and NRZI
encoding" Operational Mode (OPMODE [1:0] = 10), TERMSELECT and XCVRSELECT must be in FS
mode, TXVALID asserted, and all 0's data is presented on the TXDATA bus for at least 1ms (T1 - T2).
T0
T1
T2
T3 T4
time
SUSPENDN
XCVRSELECT &
TERMSELECT
TXVALID
DP/DM
FS Idle ('J')
'K' State
SE0
FS Mode
HS Mode
Figure 8.7 Resume Timing Behavior (HS Mode)
Table 8.9 Resume Timing Values (HS Mode)
DESCRIPTION
TIMING
PARAMETER
VALUE
T0
T1
Internal device event initiating the resume process
0 (reference)
Device asserts FS 'K' on the bus to signal resume
request to downstream port
T0 < T1 < T0 + 10ms.
T1 + 1.0ms < T2 < T1 + 15ms
T1 + 20ms
T2
The device releases FS 'K' on the bus. However by
this time the 'K' state is held by downstream port.
T3
T4
Downstream port asserts SE0.
Latest time at which a device, which was previously
in HS mode, must restore HS mode after bus activity
stops.
T3 + 1.33µs {2 Low-speed bit
times}
Revision 1.3 (10-05-04)
SMSC GT3200, SMSC USB3250
DATA3S7HEET
SMSC [ SMSC CORPORATION ]
