Hi Sir,
We found the PMBus_ALERT# pin of UCD90120A would be asserted when read the block length of MFR_DATE register(0x9D).
Here is our reproduce flow:
Step 1: Make sure no error status in STATUS_WORD(79h)
(0x68 is i2c address of our UCD90120A)
root@ubuntu:~# ipmitool i2c bus=2 0x68 0x2 0x79
00 10
00000000 00010000
Step 2: Read the block length of MFR_DATE(9Dh)
root@ubuntu:~# ipmitool i2c bus=2 0x68 0x1 0x9d
06
00000110
Step 3: Check error status in STATUS_WORD(79h)
root@ubuntu:~# ipmitool i2c bus=2 0x68 0x2 0x79
03 10
00000011 00010000
Do you have any idea of this scenario?
Thanks!