Maximum operating voltage does not match the description http://www.ti.com/lit/ds/symlink/tps92640.pdf .
Assembled circuit in accordance with http://www.ti.com/lit/ug/slvu363a/slvu363a.pdf.
We changed the schema for our task, in accordance with the recommendations http://www.ti.com/lit/ds/symlink/tps92640.pdf
It is not clear what should be changes in the scheme to work with an input voltage of 80 V.