USB2.0 PHY IC
1. If the device is suspended and it detects an SE0 state on the bus it may immediately enter the HS
handshake detection process.
2. If the device is in FS mode and an SE0 state is detected for more than 2.5µs. it may enter the HS
handshake detection process.
3. If the device is in HS mode and an SE0 state is detected for more than 3.0ms. it may enter the
HS handshake detection process. In HS mode, a device must first determine whether the SE0 state
is signaling a suspend or a reset condition. To do this the device reverts to FS mode by placing
XCVRSELECT and TERMSELECT into FS mode. The device must not wait more than 3.125ms
before the reversion to FS mode. After reverting to FS mode, no less than 100µs and no more
than 875µs later the SIE must check the LINESTATE signals. If a J state is detected the device
will enter a suspend state. If an SE0 state is detected, then the device will enter the HS Handshake
detection process.
In each case, the assertion of the SE0 state on the bus initiates the reset. The minimum reset interval
is 10ms. Depending on the previous mode that the bus was in, the delay between the initial assertion
of the SE0 state and entering the HS Handshake detection can be from 0 to 4ms.
This transceiver design pushes as much of the responsibility for timing events on to the SIE as
possible, and the SIE requires a stable CLKOUT signal to perform accurate timing. In case 2 and 3
above, CLKOUT has been running and is stable, however in case 1 the PHY is reset from a suspend
state, and the internal oscillator and clocks of the transceiver are assumed to be powered down. A
device has up to 6ms after the release of SUSPENDN to assert a minimum of a 1ms Chirp K.
8.8
HS Detection Handshake - FS Downstream Facing Port
Upon entering the HS Detection process (T0) XCVRSELECT and TERMSELECT are in FS mode. The
DP pull-up is asserted and the HS terminations are disabled. The SIE then sets OPMODE to Disable
Bit Stuffing and NRZI encoding, XCVRSELECT to HS mode, and begins the transmission of all 0's
data, which asserts a HS K (chirp) on the bus (T1). The device chirp must last at least 1.0ms, and
must end no later than 7.0ms after HS Reset T0. At time T1 the device begins listening for a chirp
sequence from the host port.
If the downstream facing port is not HS capable, then the HS K asserted by the device is ignored and
the alternating sequence of HS Chirp K's and J's is not generated. If no chirps are detected (T4) by
the device, it will enter FS mode by returning XCVRSELECT to FS mode.
Revision 1.3 (10-05-04)
SMSC GT3200, SMSC USB3250
DATA3S1HEET
SMSC [ SMSC CORPORATION ]
