Description The LM25017 is a 48V, 650mA synchronous step-down regulator with integrated high side and low side MOSFETs. The constant-on-time (COT) control scheme employed in the LM25017 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. Other protection features include thermal shutdown and bias supply undervoltage lockout (VCC UVLO). The LM25017 is available in LLP-8 and PSOP-8 plastic packages. Features Integrated 48V, High and Low Side Switches No Schottky Required Constant On-time Control No Loop Compensation Required Ultra-Fast Transient Response Nearly Constant Operating Frequency Intelligent Peak Current Limit Adjustable Output Voltage from 1.225V Precision 2% Feedback Reference Frequency Adjustable to 1MHz Adjustable Undervoltage Lockout (UVLO) Remote Shutdown Thermal Shutdown APPLICATION CIRCUIT: 12V TO 48V INPUT AND 10V, 500mA OUTPUT BUCK CONVERTER The LM25017 should be operated so the junction temperature does not exceed 150°C during normal operation. An internal Thermal Shutdown circuit is provided to protect the LM25017 in the event of a higher than normal junction temperature.