Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
SMSC USB251x 59 Revision 1.1 (04-26-10)
DATASHEET
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 t4+t5+t6+t7.
 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.
8.7.1.3 RESET_N for SMBus Slave Configuration
Figure 8.8 Reset_N Timing for SMBus Mode
Notes:
 For bus-powered configurations, the 99.5 ms (MAX) is required, and the hub and its associated
circuitry must not consume more than 100 mA from the upstream USB power source during
t5 Host acknowledges attach and signals USB
Reset.
100 msec
t6 USB Idle. undefined msec
t7 Completion time for requests (with or without data
stage).
5 msec
Table 8.10 Reset_N Timing for SMBus Mode
NAME DESCRIPTION MIN TYP MAX UNITS
t1 RESET_N Asserted. 1 μsec
t2 Hub Recovery/Stabilization. 500 μsec
t3 SMBus Code Load (See Note). 250 300 msec
t4 Hub Configuration and USB Attach. 100 msec
t5 Host acknowledges attach and signals USB
Reset.
100 msec
t6 USB Idle. Undefined msec
t7 Completion time for requests (with or without data
stage).
5 msec
Table 8.9 Reset_N Timing for EEPROM Mode (continued)
NAME DESCRIPTION MIN TYP MAX UNITS
t1
t2 t4
t5
t6 t7
RESET_N
VSS
Hardware
reset
asserted
Reset
Negation
SMBus Code
Load
Attach
USB
Upstream
USB Reset
recovery
Idle
Start
completion
request
response
t3
Hub PHY
Stabilization