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USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 1.0 (3-11-09) 56 SMSC USB251x
DATASHEET
8.6.1.1 RESET_N for Strapping Option Configuration
Figure 8.3 Reset_N Timing for Default/Strap Option Mode
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.
Table 8.7 Reset_N Timing for Default/Strap Option Mode
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
Strap Pins
VSS
Hardware
reset
asserted
Read Strap
Options
Drive Strap
Outputs to
inactive
levels
Attach
USB
Upstream
USB Reset
recovery
Idle
Start
completion
request
response
t2
t3
Don’t Care
Don’t Care