TI has introduced the LM5017 buck regulator.
The LM5017 is a 100 V, 600 mA synchronous step-down regulator with integrated high side and low side MOSFETs. The constant-on-time (COT) control scheme employed in the LM5017 requires no loop compensation, provides excellent transient response, and enables very low step-down ratios. The on-time varies inversely with the input voltage resulting in nearly constant frequency over the input voltage range. A high voltage startup regulator provides bias power for internal operation of the IC and for integrated gate drivers.
A peak current limit circuit protects against overload conditions. The undervoltage lockout (UVLO) circuit allows the input undervoltage threshold and hysteresis to be independently programmed.
The device comes in LLP-8 and PSOP-8 packages. You can download the 17 page datasheet PDF here.