TPS54550: The reason of oscillating output, when SSENA connected with TPS3808 and pull-up resistor.

Hi,

My customer connected the output of the power supply monitoring IC (TPS3808) to the SSENA pin of TPS54550. Since the output of TPS3808 is open-drain output, pull-up resistor (4.7k connected with 3.3V power supply) is also connected with SSENA pin.

On this case, he observed the SSENA pin is oscillating and the output is oscillating as well. Could you please advise us whether the reason of this phenomena is to add external pull-up resistors on SSENA pin?

Of course, he knows Not using external pull-up resistors on SSENA pin, and he plans to modify it. However, he wants to know the reason of current phenomena.

Thanks and best regards,
M.HATTORI