LM25005,pdf datasheet (42V, 2.

The LM25005 switching regulator features all of the functions
necessary to implement an efficient, high voltage buck regulator
using a minimum of external components. This easy to
use regulator includes a 42V, 160mΩ, N-channel MOSFET,
with an output current capability of 2.5 Amps. The regulator
control method is based upon current mode control utilizing
an emulated current ramp. Current mode control provides inherent
line voltage feed-forward, cycle-by-cycle current limiting
and ease of loop compensation. The use of an emulated
control ramp reduces noise sensitivity of the pulse-width modulation
circuit, allowing reliable control of very small duty
cycles necessary in high input voltage applications. The operating
frequency is programmable from 50kHz to 500kHz.
An oscillator synchronization pin allows multiple LM25005
regulators to self-synchronize or to be synchronized to an external
clock. Additional protection features include: current
limit, thermal shutdown and remote shutdown capability. The
device is available in a power enhanced TSSOP-20 package
featuring an exposed die attach pad to aid thermal dissipation.