We have two DS32ELX0421 ICs that fail to lock the PLL clock (reg 2A) at power up between ambient temperatures 37C to 55C. The IC works at all other temperatures from -32C to 70C.
On power up the PLL not locked register is set. We have verified communication to the IC, all register are set correctly at power on. We have verified all input signals are available to the IC at power up.
At a failure, we can manually send a software reset and then write the registers to get the IC to work correctly.
To verify the fault is isolate to the IC: We removed the suspected IC and replaced with the same type of IC. The board was verified working across all temperatures. We reinstalled the suspected IC. Again the board failed between ambient temperatures 37C to 55C.