Hi David,
I recreated the design using TPS53319 with customer specs, updated the inductor to XAL6030-561ME. Input 0.56uH as inductance, and DCR as 3.1mOhm, and I see the pop up that warns about instability. The reason for the pop-up is that, for the WEBENCH generated design, the max limit for DCR is 0.8mOhm. This, because WEBENCH does not currently re-calculate the compensation and we cannot gaurantee stability in the design with custom components.
However, we are working on this feature, as we speak. Pretty soon, we hope to have re-compensation calculator activated in WEBENCH, where customer can change critical components and re-design compensation.
Sorry for any inconvenience caused. Please let me know if I can be of further assistance.
Regards,
Pavani Jella
WEBENCH Applications