Hi Arumagam,
I have not found a 4-layer reference design for LMZ31530; both the EVM and PMP9464 reference design I found are 6-layer designs.
The SOA curves in the datasheet (Fig 4-6 for Vin=12V; Fig. 10-12 for Vin=5V) assume 100 mm × 100 mm six-layer PCB…
Hi,
I would have think that it will be high impedance.
Maybe this sample design will helps. It uses 2 different supply for the LM10011 and the converter that it try to control
http://www.ti.com/tool/PMP9464
Thanks
-Arief