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SMSC USB2512B User Manual

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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 
, 
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