The LM25019MR/NOPB is a constant on-time synchronous Buck Regulator with integrated high-side and low-side MOSFETs. The constant on-time (COT) control scheme employed in the LM25019 requires no loop compensation, provides excellent transient response and enables very high 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 start-up 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 under-voltage lockout (UVLO) circuit allows the input under-voltage threshold and hysteresis to be independently programmed. Other protection features include thermal shutdown and bias supply under-voltage lockout.