The LM5116 is a synchronous buck controller intended for step-down regulator applicationsfrom a high-voltage or widely varying input supply. The control method is based upon current modecontrol utilizing an emulated current ramp. Current mode control provides inherent linefeed-forward, cycle-by-cycle current limiting, and ease-of-loop compensation. The use of anemulated control ramp reduces noise sensitivity of the pulse-width modulation circuit, allowingreliable control of very small duty cycles necessary in high-input voltage applications.
The operating frequency is programmable from 50 kHz to 1 MHz. The LM5116 drives externalhigh-side and low-side NMOS power switches with adaptive dead-time control. A user-selectable diodeemulation mode enables discontinuous mode operation, for improved efficiency at light loadconditions. A low quiescent current shutdown disables the controller and consumes less than 10 µAof total input current.
Additional features include a high-voltage bias regulator, automatic switch-over toexternal bias for improved efficiency, thermal shutdown, frequency synchronization, cycle-by-cyclecurrent limit, and adjustable line undervoltage lockout. The device is available in a powerenhanced HTSSOP-20 package featuring an exposed die attach pad to aid thermal dissipation.