X80000, X80001 pdf datasheet (

The X80000 contains three major functions: a power
communications controller, a power sequencing controller,
and a hotswap controller.
The power communications controller allows smart power
supply control via the backplane using the SMBus protocol.
The system can check for voltage, current, and
manufacturing ID compliance before board insertion. The
power distribution network can monitor the status of the
negative voltage supply, DC voltage supplies, and hardshort
events by accessing the Fault Detection Register and
General Purpose EEPROM of the device. Each device has a
unique slave address for identification.
The power sequencer controller time sequences up to five
DC-DC modules. The X80000 allows for various hardwired
configurations, either parallel or relay sequencing modes.
The power good, enable and voltage good signals provide
for flexible DC-DC timing configurations. Each voltage
enable signal has a programmable delay. In addition, the
voltage good signals can be monitored remotely via the fault
detection register (thru the SMBus).