USB2524_07 Datasheet, PDF (50/57 Pages) SMSC Corporation – USB MultiSwitchTM Hub

9.1.1.3 RESET_N for SMBus Slave Configuration
Hardware
reset
asserted
Reset
Negation
SMBus Code
Load
Hub PHY
Stabilization
Attach
USB
Upstream
USB Reset
recovery
USB MultiSwitch^TM Hub
Datasheet
Start
completion
Idle
request
response
RESET_N
t1
t2
t3
t4
t5
t6
t7
VSS
Figure 9.3 Reset_N Timing for SMBus Mode
Table 9.3 Reset_N Timing for SMBus Mode
NAME
DESCRIPTION
MIN
TYP
t1
RESET_N Asserted.
1
t2
Hub Recovery/Stabilization.
t3
SMBus Code Load (See Note 9.3)
250
t4
Hub Configuration and USB Attach.
t5
Host acknowledges attach and signals USB
100
Reset.
t6
USB Idle.
Undefined
t7
Completion time for requests (with or without data
stage).
MAX
500
300
100
5
UNITS
μsec
μsec
msec
msec
msec
msec
msec
9.1.2
Note: For Bus-Powered configurations, the Hub and its associated circuitry will consume more than
100mA from the upstream USB power source during t2+t3+t4+t5+t6+t7.
Note 9.3 For Self-Powered configurations, t3 MAX is not applicable and the time to load the
configuration is determined by the external SMBus host.
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.
„ Sets default address to 0.
„ Sets configuration to: Unconfigured.
„ Negates PRTPWR[4:1] to all downstream ports.
„ Clears all TT buffers.
„ Moves device from suspended to active (if suspended).
Revision 1.91 (08-22-07)
50
DATASHEET
SMSC USB2524