USB 2.0 Hi-Speed 2-Port Hub Controller
Datasheet
4. The external crystal oscillator is halted.
5. The PLL is halted.
Note: All power supplies must have reached the operating levels mandated in Section 9.2, "Operating
Conditions**," on page 52, prior to (or coincident with) the assertion of RESET_N.
8.3.3
USB Bus Reset
In response to the upstream port signaling a reset to the device, the device performs the following:
Note: The device does not propagate the upstream USB reset to downstream devices.
1. Sets default address to 0.
2. Sets configuration to: Unconfigured.
3. Moves device from suspended to active (if suspended).
4. Complies with Section 11.10 of the USB 2.0 Specification for behavior after completion of the
reset sequence.
The host then configures the device in accordance with the USB Specification.
8.4
Link Power Management (LPM)
The device supports the L0 (On), L1 (Sleep), and L2 (Suspend) link power management states per
the USB 2.0 Link Power Management Addendum. These supported LPM states offer low transitional
latencies in the tens of microseconds versus the much longer latencies of the traditional USB
suspend/resume in the tens of milliseconds. The supported LPM states are detailed in Table 8.3. For
additional information, refer to the USB 2.0 Link Power Management Addendum.
Table 8.3 LPM State Definitions
STATE
DESCRIPTION
ENTRY/EXIT TIME TO L0
Entry: ~3 ms
L2
L1
L0
Suspend
Sleep
Exit: ~2 ms
Entry: ~65 us
Exit: ~100 us
Fully Enabled (On)
-
Note: State change timing is approximate and is measured by change in power consumption.
Note: System clocks are stopped only in suspend mode or when power is removed from the device.
8.5
Remote Wakeup Indicator (SUSP_IND)
The remote wakeup indicator feature uses the SUSP_IND as a side band signal to wake up the host
when in suspend. This feature is enabled and disabled via the HUB_RESUME_INHIBIT configuration
bit in the hub configuration space register CFG3. The only way to control the bit is by configuration
EEPROM, SMBus or internal ROM default setting. The state is only modified during a power on reset,
or hardware reset. No dynamic reconfiguring of this capability is possible.
Revision 1.0 (06-17-13)
48
SMSC USB2532
DATASHEET
SMSC [ SMSC CORPORATION ]
