USB 2.0 Hi-Speed Hub Controller
Datasheet
8.6.1.1
RESET_N for Strapping Option Configuration
Drive Strap
Start
completion
request
response
Hardware
reset
asserted
Attach
USB
Upstream
Read Strap
Options
Outputs to
inactive
levels
USB Reset
recovery
Idle
t7
t8
t1
t2
t6
t5
t3
RESET_N
VSS
t4
Strap Pins
VSS
Don’t Care
Valid
Driven by Hub if strap is an output.
Don’t Care
Figure 8.3 Reset_N Timing for Default/Strap Option Mode
Table 8.7 Reset_N Timing for Default/Strap Option Mode
NAME
DESCRIPTION
MIN
TYP
MAX
UNITS
t1
t2
t3
t4
t5
t6
RESET_N Asserted.
1
μsec
nsec
nsec
μsec
msec
msec
Strap Setup Time
16.7
16.7
Strap Hold Time.
1400
2
hub outputs driven to inactive logic states
USB Attach (See Note).
1.5
100
Host acknowledges attach and signals USB
Reset.
100
t7
t8
USB Idle.
undefined
msec
msec
Completion time for requests (with or without data
stage).
5
Notes:
When in bus-powered mode, the hub and its associated circuitry must not consume more than 100
mA from the upstream USB power source during t1+t5.
All power supplies must have reached the operating levels mandated in Chapter 9, DC Parameters,
prior to (or coincident with) the assertion of RESET_N.
Revision 1.0 (3-11-09)
56
SMSC USB251x
DATASHEET
SMSC [ SMSC CORPORATION ]
