Industrial Temperature Rated USB 2.0 High-Speed 2-Port Hub Controller
Datasheet
Revision 1.92 (11-28-07)
30
SMSC USB2512i
DATASHEET
4.6.2.3
RESET_N for SMBus Slave Configuration
Figure 4.5 Reset_N Timing for SMBus Mode
Notes:
For Bus-Powered configurations, the 99.5ms (MAX) is required, and the Hub and its associated
circuitry must not consume more than 100mA from the upstream USB power source during
t2+t3+t4+t5+t6+t7. For Self-Powered configurations, t3 MAX is not applicable and the time to load
the configuration is determined by the external SMBus host.
All Power Supplies must have reached the operating levels mandated in
, prior to (or coincident with) the assertion of RESET_N.
4.6.3
USB Bus Reset
In response to the upstream port signaling a reset to the Hub, the Hub does the following:
Note:
The Hub does not propagate the upstream USB reset to downstream devices.
1. Sets default address to 0.
2. Sets configuration to: Unconfigured.
3. Negates PRTPWR[2:1] to all downstream ports.
Table 4.5 Reset_N Timing for SMBus Mode
NAME
DESCRIPTION
MIN
TYP
MAX
UNITS
t1
RESET_N Asserted.
1
μ
sec
t2
Hub Recovery/Stabilization.
500
μ
sec
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
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
