82598EB Datasheet, PDF (573/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - Resets
8.7
Resets
After power is applied to the 82598 controller, it must be reset. There are two ways to do this: (1) using
the Internal Power On Reset circuit and (2) using the external LAN_PWR_GOOD signal. By default,
Internal Power On Reset will reset the chip. If the design relies on Internal Power On Reset, then the
power supply sequencing timing requirement (see Section 7.4.2) between the 1.8 V dc and 1.2 V dc
power rails has to be met. If this requirement is impossible to meet, the alternative is to bypass the
Internal Power On Reset circuit by pulling POR_BYPASS high and using an external power monitoring
solution to provide a LAN_PWR_GOOD signal. For LAN_PWR_GOOD timing requirements, see
Section 7.6.6.
Table 8-4. Reset Context for POR_BYPASS and LAN_PWR_GOOD
POR_BYPASS
Active Reset Circuit
If = 0b
LAN_PWR_GOOD
If = 1b
External Reset
LAN_PWR_GOOD
If = 0b
Held in reset
If = 1b
Initialized, ready for normal operation
It is important to ensure that resets for the BMC and the 82598 are generated within a specific time
interval. The NC-SI specification calls out a requirement of link establishment in two seconds of the
BMC receiving the power good signal from the platform.
To achieve link within the time specified, the 82598 and external BMC need to receive power good
signals from the platform within one second of each other. This causes an Internal Power On Reset; the
NC-SI interface is also reset, ready to link. The BMC should poll this interface and to establish link for
two seconds to ensure compliance.
8.8
NC-SI Layout Requirements
8.8.1 Board Impedance
The NC-SI manageability interface is a single ended signaling environment and as such we recommend
a target board and trace impedance of 50  plus 20% and minus 10%. This ensures optimal signal
integrity.
8.8.2 Trace Length Restrictions
We recommend a trace length maximum value from a board placement and routing topology
perspective of eight inches for direct connect applications. This ensures signal integrity and quality is
preserved from a design perspective and that compliance is met for NC-SI electrical requirements.
573