Hi-Speed USB Device PHY with UTMI Interface

Datasheet

8.6Suspend 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

0 (reference)

 

or a SUSPEND.

 

 

 

 

T1

The time at which the device must place itself

HS Reset T0 + 3. 0ms < T1 < HS Reset T0

 

in FS mode after bus activity stops.

+ 3.125ms

 

 

 

T2

SIE samples LINESTATE. If LINESTATE = 'J',

T1 + 100 µs < T2 <

 

then the initial SE0 on the bus (T0 - T1) had

T1 + 875µs

 

been due to a Suspend state and the SIE

 

 

remains in HS mode.

 

 

 

 

T3

The earliest time where a device can issue

HS Reset T0 + 5ms

 

Resume signaling.

 

 

 

 

T4

The latest time that a device must actually be

HS Reset T0 + 10ms

 

suspended, drawing no more than the

 

 

suspend current from the bus.

 

 

 

 

SMSC USB3280

31

Revision 1.5 (11-15-07)

 

DATASHEET