Datasheet

2-Port USB 2.0 Hi-Speed Hub Controller
Datasheet
SMSC USB2412 15 Revision 1.3 (12-27-11)
DATASHEET
3.2.1.1 RESET_N
Figure 3.1 Reset_N Timing
Note: All power supplies must have reached the operating levels mandated in Chapter 4, DC
Parameters, prior to (or coincident with) the assertion of RESET_N.
3.2.2 USB Bus Reset
In response to the upstream port signaling a reset to the hub, the hub does the following:
1. Sets default address to 0.
2. Sets configuration to unconfigured.
3. Negates PRTPWR[2:1] to all downstream ports.
4. Clears all TT buffers.
5. Moves device from suspended to active (if suspended).
6. Complies with Section 11.10 of the USB 2.0 Specification for behavior after completion of the reset
sequence. The host then configures the hub and the hub’s downstream port devices in accordance
with the specification.
Note: The hub does not propagate the upstream USB reset to downstream devices.
Table 3.1 Reset_N Timing
NAME DESCRIPTION MIN TYP MAX UNITS
t1 RESET_N asserted 1 μsec
t2 Strap setup time 16.7 nsec
t3 Strap hold time 16.7 1400 nsec
t4 Hub outputs driven to inactive logic states 1.5 2 μsec
t5 USB attach (See Note) 100 msec
t6 Host acknowledges attach and signals USB reset 100 msec
t7 USB idle undefined msec
t8 Completion time for requests (with or without data
stage)
5 msec
t1
t4
t5
t6
t7 t8
Valid Driven by Hub if strap is an output
RESET_N
VSS
NON_REM[1:0]
VSS
Hardware
reset asserted
Read
NON_REM[1:0]
p
Outputs to
inactive levels
USB
Upstream
USB Reset
recovery Idle
Start completion
request response
t2
t3
Don’t Care
Don’t Care