USB3290 datasheet(31/46 Pages) SMSC

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Small Footprint Hi-Speed USB 2.0 Device PHY with UTMI Interface

Datasheet

SMSC USB3290

Revision 1.5 (11-02-07)

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)

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

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