September 28, 2010
LM5119
Wide Input Range Dual Synchronous Buck Controller
General Description
Features
The LM5119 is a dual synchronous buck controller intended
for step-down regulator applications from a high voltage or
widely varying input supply. The control method is based up-
on current mode control utilizing an emulated current ramp.
Current mode control provides inherent line feed-forward, cy-
cle-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 ap-
plications. The switching frequency is programmable from
50kHz to 750kHz. The LM5119 drives external high-side and
low-side NMOS power switches with adaptive dead-time con-
trol. A user-selectable diode emulation mode enables discon-
tinuous mode operation for improved efficiency at light load
conditions. A high voltage bias regulator with automatic
switch-over to external bias further improves efficiency. Ad-
ditional features include thermal shutdown, frequency syn-
chronization, cycle-by-cycle and hiccup mode current limit
and adjustable line under-voltage lockout. The device is avail-
able in a power enhanced leadless LLP-32 package featuring
an exposed die attach pad to aid thermal dissipation.
Emulated peak current mode control
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Wide operating range from 5.5V to 65V
Easily configurable for dual outputs or interleaved single
output
Robust 3.3A peak gate drive
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Switching frequency programmable to 750kHz
Optional diode emulation mode
Programmable output from 0.8V
Precision 1.5% voltage reference
Programmable current limit
Hiccup mode overload protection
Programmable soft-start
Programmable line under-voltage lockout
Automatic switch-over to external bias supply
Channel2 enable logic input
Thermal Shutdown
Leadless LLP32 (5mm x 5mm) package
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Typical Application
30124001
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