PTD08A020W: Voltage delivered on Vout with no PWN pulse, pwr_inh low and no SRE

Hello,

I am using PTD08A020W modules on my PCIe board with a Xilinx Virtex6.
Schematic was based on ML605 Evaluation Kit.
When voltage is rising from 0V to 12V, the PTD08A020W start to deliver 1V on Vout when Vin is around 3.6V.
Usually, the voltage waits for the SRE signal rise to be delivered.
There is a UCD9248 controller to manage all the power rails.
12V is delivered by the server through the PCIe slot.
There is a TPS24772 on the server side to manage power supply.
Please see below a power-on sequence screen-shot.
TPS24772 controller seems to limit voltage on the 12V input to prevent from a too important current rise.
Do you know any reason why the DC/DC module is already delivering voltage?

Thanks and best regards,

Louis