8.4.13 Data and Error Logging to EEPROM Memory

The UCD90320 provides fault log, device reset counter, and peak readings for each rail. To reduce stress on the EEPROM memory, a 30-second timer is started if a measured value exceeds the previously logged value. Only the highest value from the 30-second interval is written from RAM to EEPROM.

Faults are stored in EEPROM memory and are accessible over PMBus. Each logged fault includes the following information:

• Rail number
• Fault type
• Fault time since previous device reset
• Last measured rail voltage

The total number of device resets is also stored to EEPROM memory. The value can be reset using PMBus.

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.