UCD90124A: data flash was erased accidently

Hi

Please send your sch and project file.

Regards

Yihe

Address80_UCD90124A.xml

Hi, Yihe 

The sch and project file are attached. 

Regards

Hi

Please correct your design to follow the data sheet.

V33FB shall be NC.

Here is the UCD sch review guideline

https://www.ti.com/lit/pdf/slvub50 

Regards

Yihe

Hi, Yihe 

We use this UCD sch in lots of projects for a long time, we never encounter this issue before. We have three UCD90124A in this project, but only the 0x80 UCD device' data flash would be erased randomly in power-off condictions.  

We use 12V power rail to generate the 3.3V voltage for UCD like typical application sch and evluation module. If leave the V33FB unconnected, how to generate 3.3V voltage for  UCD devices? 

Hi

That diagram is from the first Gen UCD and we do not recommend it. Did you start the project from UCD90124 which is different with UCD90124A. 

Typically, customer also uses a LDO or standby 3v3 to supply UCD since it is low current device.

Hi, Yihe

Yes, we start project from UCD90124, and it was replaced with UCD90124A about 3 years ago. We haven't encounter this issue ever.  In addtion, the connections of V33FD of three UCD90124A in this project are same, why the other two UCD90124A work well? 

Is there any other reason cause this issue ?

Regards

Powell

Hi

How many units have this problem and how often does it happen? 

Will you host partially update the flash?

Regards

Yihe 

Hi

We may find the cause of the problem, It seems caused by the PMBUS driver. 

When our system boot up, the host will send all PMBUS commands to UCD90124A for initilization. When send some unsupported commands, the I2C controller can't receive ACK signals, turn off the power in this time, the issue will be replicated.