UCD90320
ZHCSFI3B –AUGUST 2016–REVISED MAY 2019
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The run time clock value is logged into EEPROM when a power down is detected. This allows UCD90320 to
preserve the run-time clock value through resets or power cycles.
It is also possible to update and calibrate the UCD90320 internal run-time clock via a PMBus host. For example,
a host processor with a real-time clock could periodically update the UCD90320 run-time clock to a value that
corresponds to the actual date and time. The host must translate the UCD90320 timer value back into
appropriate units, based on the usage scenario chosen. See the REAL_TIME_CLOCK command in the
UCD90320 Sequencer and System Health Controller PMBus Command Reference for more details.
8.4.14 Black Box First Fault Logging
The first fault in a system failure event is usually critical to diagnose the root cause. An innovative Black Box
Fault Logging feature is introduced in UCD90320 to accelerate the debugging process. When UCD90320 detects
the first fault, the device records and saves the status of each rail and I/O pin in a special area of the EEPROM
reserved for this function. The device does not save the subsequent faults and monitoring statuses into the Black
Box Fault Log, but instead records them into the standard fault log. The Black Box Fault Log must be cleared in
order to acknowledge the next fault.
Figure 34. Black Box Fault Logging Window (Status ►Blackbox Info tab)
8.4.15 PMBus Address Selection
Three digital input pins are allocated to decode the PMBus address. At power up, UCD90320 detects the logic
inputs of the three address pins to determine the configured PMBus address.
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