HP AB464-9003F Service Manual page 24

Figure 5 Power Subsystem Block Diagram
Two hot-swappable AC/DC power supplies generate main system power and standby power
voltage. One active power supply is sufficient to operate the system at maximum load. Each
power supply receives AC power through the integrated AC inlet. The system can operate at
180-264 V AC and achieve 1+1 redundancy. The power supplies are power factor corrected and
the maximum dc power output of the power system is 1600 W. Service the hot-swappable power
supplies by sliding them out the rear of the chassis.
Power Button
The Power button on the server is a momentary contact push button. The BMC polls the front
panel Power button at a rate of at least 2 Hz. The Power button is an input to the System Power
State Management. If the system is off, a single button press will turn on the system. If the system
has booted to an OS, and a short button press is detected, a graceful-shutdown request will be
sent to the system by pulsing ACPI_PWR_BTN_L; when the ACPI bits are set to note the OS
has shut down, the BMC will perform a hard power down. If the system has not booted to an OS,
or if a long (5 second) button press is detected, the system will do an immediate hard power off.
System Power State Management
The system power may be controlled from the Power button, an IPMI Chassis command,
Wake-On-LAN, loss or gain of AC.
Applying System Power in normal customer usage, the server runs on 180 to 264V. Standby
power will be supplied on either; hence the BMC will power up when the power supplies are
plugged in. The BPS0_AC_OK and BPS1_AC_OK signals indicate whether the AC voltage to
the power supplies is within the required range. If neither BPS0_AC_OK nor BPS1_AC_OK is
asserted, then the BMC should log an event and prevent the system from turning on.
Procedure 1 Power On Sequence
1. Update the cache of DIMM SPD information.
2. Ensure that the memory board is detected and that the cpu board has a processor in socket
0. If these FRUs are not detected, the BMC logs an event against the Missing Device sensor
(sensor 0x15).
24 Overview