USB3250 datasheet(35/48 Pages) SMSC

35 / 48 page

USB2.0 PHY IC

Datasheet

SMSC GT3200, SMSC USB3250

Revision 1.5 (03-24-06)

DATASHEET

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.

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:

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)

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

The earliest time where a device can issue

Resume signaling.

HS Reset T0 + 5ms

The latest time that a device must actually be

suspended, drawing no more than the suspend

current from the bus.

HS Reset T0 + 10ms

Last

Activity

'J' State

Soft SE0

Device is suspended

SUSPENDN

XCVRSELECT

DP/DM

TERMSELECT

time

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