Power-Up Sequence; Power Down Sequence; Power Control Sources; Table 27. Power Control Initiators - Intel X38ML - Server Board Motherboard Technical Manual

Platform Management
3. The BMC waits 10 seconds. If the power state retention feature is configured to power
on the server after an AC loss, it attempts to power up the server. This is the case when
either the AC dropped out momentarily, but not long enough to reset the BMC, or the
power subsystem had a momentary failure that the BMC could not differentiate from a
momentary AC loss.
The BMC responds to the power loss interrupt with 1 to 2 ms if it is in operational mode.
5.2.3

Power-up Sequence

To power up the server, the BMC simulates the front panel power button being pressed for 8
seconds or until PS_PWRGD is asserted. If PS_PWRGD is not asserted within 8 seconds, then
a fault is generated. See Section 5.17.3.
After simulating the front panel power button press, the BMC initializes all sensors to their
power-on initialization state. The initialization agent is run.
5.2.4

Power Down Sequence

To power down the system, the BMC simulates the front panel power button being pressed for 8
seconds or until PS_PWRGD is deasserted. If PS_PWRGD is not deasserted within 8 seconds,
then a fault is generated. See Section 5.17.3.
Before initiating the system power down, the BMC stops scanning any sensors that should not
be scanned in the powered-down state.
5.2.5

Power Control Sources

The following sources can initiate power-up and/or power-down activity:
Source
Power button
BMC watchdog timer
Platform event filtering
Command
Power state retention
Chipset
5.2.5.1 Power Button Signal
The POWER_BUTTON signal toggles the system power. This signal is activated by a
momentary contact switch on the front panel assembly and is routed to the BMC. The BMC de-
bounces and monitors the signal. The signal must be in a constant state for 8 ms before it is
treated as asserted.
56

Table 27. Power Control Initiators

External Signal Name or
Internal Subsystem
Front panel power button
Internal BMC timer
PEF
Routed through command processor
Implemented via BMC internal logic
Sleep S4/S5 signal (same as
POWER_ON)
Intel order number E15331-006
Intel® Server Board X38ML
Capabilities
Turns power on or off
Turns power off, or power cycle
Turns power off, power cycle, or reset
Turns power on or off, or power cycle
Turns power on when AC power returns
Turns power on or off
Revision 1.3