TINA-TI: transient simulation with TPS54425 and TPS74401

I am not sure if this is a simulation bug or not, however, when I run the TPS74401 model by itself using a 2V input, 5V bias, Vout=1.8V, and Iout=2A, the simulation works correctly.

The TPS74401 does have a typical Dropout of 120mV, however, the maximum value is very close to 200mV, which, in this case is where your customer has the device functioning. This does NOT explain the results your customer is getting in simulation, however. When I change the simulation parameters, the "noise" changes, but I cannot seem to eliminate it.

As a test, I took the output waveform from the TPS54425 and used it as the input to the TPS74401 stand alone and got a similar amount of noise in the simulation. The device apparently does not "like" the waveform from the switcher.

Hi Britt,

Thank you for your reply and support.
I attach the wave pattern which customer simulated.
I think that a noise occurs to a wave pattern of TPS54425 if caused by a noise of DCDC.
If you need more information or if  I should  clarify my comment ,please let me know.
TPS54425PWPR_TPS74401RGWR simulation waveform.zip

Best Regards,
Yusuke　/ Japan Disty