Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
SMSC USB251xB/xBi 43 Revision 2.3 (06-11-13)
DATASHEET
5.5.1.1 RESET_N for Strapping Option Configuration
Figure 5.3 Reset_N Timing for Default Configuration
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 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 outputs driven to inactive logic states 1.5 2
μs
t5 USB attach (see notes) 100 ms
t6 Host acknowledges attach and signals USB reset 100 ms
t7 USB idle undefined ms
t8 Completion time for requests (with or without data
stage)
5msec
t1
t4
t5
t6
t7 t8
valid driven by hub if strap is an output
RESET_N
VSS
CFG_SEL[2:0]
VSS
Hardware
reset asserted
Read
CFG_SEL[1:0]
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