USB2502-AEZG Standard Microsystems (SMSC), USB2502-AEZG Datasheet - Page 33

• Manufacturer Part Number: USB2502-AEZG
• Manufacturer: Standard Microsystems (SMSC)

Specifications of USB2502-AEZG

• Lead Free Status / RoHS Status: Compliant

2-Port USB 2.0 Hub Controller
Datasheet
SMSC USB2502
5.6.1
5.6.1.1
NAME
RESET_N
Strap Pins
t1
t2
t3
t4
t5
VSS
VSS
Hardware
asserted
reset
RESET_N Asserted.
Strap Setup Time
Strap Hold Time.
hub outputs driven to inactive logic states
USB Attach (See Note).
External Hardware RESET_N
A valid hardware reset is defined as, assertion of RESET_N for a minimum of 1us after all power
supplies are within operating range. While reset is asserted, the Hub (and its associated external
circuitry) consumes less than 500 μ A of current from the upstream USB power source (300 μ A for the
Hub and 200 μ A for the external circuitry).
Assertion of RESET_N (external pin) causes the following:
1. All downstream ports are disabled, and PRTPWR power to downstream devices is removed.
2. The PHYs are disabled, and the differential pairs will be in a high-impedance state.
3. All transactions immediately terminate; no states are saved.
4. All internal registers return to the default state (in most cases, 00(h)).
5. The external crystal oscillator is halted.
6. The PLL is halted.
7. LED indicators are disabled.
The Hub is “operational” 500 μ s after RESET_N is negated.
Once operational, the Hub immediately reads OEM-specific data from the external EEPROM (if the
SMBus option is not disabled).
RESET_N for Strapping Option Configuration
Don’t Care
Read Strap
t1
Options
Figure 5.2 Reset_N Timing for Default/Strap Option Mode
Table 5.5 Reset_N Timing for Default/Strap Option Mode
DESCRIPTION
t2
Valid
t3
t4
Don’t Care
Drive Strap
Outputs to
inactive
DATASHEET
levels
t5
33
Upstream
Attach
USB
Driven by Hub if strap is an output.
16.7
16.7
MIN
1
USB Reset
recovery
t6
TYP
2.0
t7
Idle
MAX
1400
100
1.5
Revision 2.3 (08-27-07)
t8
completion
response
request
Start
UNITS
msec
μ sec
nsec
nsec
μ sec