Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
SMSC USB251xB/xBi 47 Revision 2.2 (02-17-12)
DATASHEET
5.5.1.3 RESET_N for SMBus Slave Configuration
Figure 5.5 Reset_N Timing for SMBus Mode
Note 5.1 For bus-powered configurations, there is a 99.5 ms MAX, and the hub and its associated
circuitry must not consume more than 100 mA from the upstream USB power source
during t4+t5+t6+t7+t8+t9. For self-powered configurations, t5 MAX is not applicable and
the time to load the configuration is determined by the external SMBus host.
Note 5.2 All power supplies must have reached the operating levels mandated in Chapter 6: DC
Parameters, prior to (or coincident with) the assertion of RESET_N.
NAME DESCRIPTION MIN TYP MAX UNITS
t1 RESET_N Asserted 1 μs
t2 CFG_SEL[1:0] setup time 16.7 ns
t3 CFG_SEL[1:0] hold time 16.7 1400 ns
t4 Hub recovery/stabilization 500
μs
t5
BUS
SMBus code load (Note 5.1)99.5ms
t5
SELF
SMBus Code Load (Note 5.1) undefined ms
t6 Hub configuration and USB attach 100 ms
t7 Host acknowledges attach and signals USB reset 100 ms
t8 USB idle undefined ms
t9 Completion time for requests (with or without data
stage)
5ms
t1
t4
t6 t7 t8 t9
RESET_N
VSS
Hardware
reset asserted
Read
CFG_SEL[1:0]
SMBus code
load
Attach USB
upstream
USB reset
recovery
Idle
Start completion
request response
t5
Hub PHY
stabilization
valid
CFG_SEL[2:0]
VSS
don’t care don’t care
t2
t3