The LM25116 is a synchronous buck controller intended for step-down regulator applications from a high voltage or widely varying input supply. The control method is based upon current mode control utilizing an emulated current ramp. Current mode control provides inherent line 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 50 kHz to 1 MHz. The LM25116 drives external high-side and low-side NMOS power switches with adaptive dead-time control. A user-selectable diode emulation mode enables discontinuous mode operation for improved efficiency at light load conditions. A low quiescent current shutdown disables the controller and consumes less than 10 µA of total input current. Additional features include a high voltage bias regulator, automatic switch-over to external bias for improved efficiency, thermal shutdown, frequency synchronization, cycle by cycle current limit and adjustable line under-voltage lockout. The device is available in a power enhanced HTSSOP-20 package featuring an exposed die attach pad to aid thermal dissipation.

• Emulated peak current mode
• Wide operating range up to 42V
• Low IQ shutdown (< 10 µA)
• Drives standard or logic level MOSFETs
• Robust 3.5A peak gate drive
• Free-run or synchronous operation to 1 MHz
• Optional diode emulation mode
• Programmable output from 1.215V to 36V
• Precision 1.5% voltage reference
• Programmable current limit
• Programmable soft-start
• Programmable line under-voltage lockout
• Automatic switch to external bias supply
• HTSSOP-20 exposed pad
• Thermal shutdown