The LM5116 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 LM5116 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 undervoltage lockout. The device is available in a power
enhanced HTSSOP-20 package featuring an exposed die attach pad to aid thermal dissipation.
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