LM3151 Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – SIMPLE SWITCHER® CONTROLLER, High Input Voltage Synchronous Step-Down

LM3151/LM3152/LM3153
August 26, 2009
SIMPLE SWITCHER^® CONTROLLER, High Input Voltage
Synchronous Step-Down
General Description
The LM3151/2/3 SIMPLE SWITCHER^® Controller is an easy
to use and simplified step down power controller capable of
providing up to 12A of output current in a typical application.
Operating with an input voltage range from 6V-42V, the
LM3151/2/3 features a fixed output voltage of 3.3V, and fea-
tures switching frequencies of 250 kHz, 500 kHz, and 750
kHz. The synchronous architecture provides for highly effi-
cient designs. The LM3151/2/3 controller employs a Constant
On-Time (COT) architecture with a proprietary Emulated Rip-
ple Mode (ERM) control that allows for the use of low ESR
output capacitors, which reduces overall solution size and
output voltage ripple. The Constant On-Time (COT) regula-
tion architecture allows for fast transient response and re-
quires no loop compensation, which reduces external com-
ponent count and reduces design complexity.
Fault protection features such as thermal shutdown, under-
voltage lockout, over-voltage protection, short-circuit protec-
tion, current limit, and output voltage pre-bias startup allow for
a reliable and robust solution.
The LM3151/2/3 SIMPLE SWITCHER^® concept provides for
an easy to use complete design using a minimum number of
external components and National’s WEBENCH^® online de-
sign tool. WEBENCH^® provides design support for every step
of the design process and includes features such as external
component calculation with a new MOSFET selector, electri-
cal simulation, thermal simulation, and Build-It boards for
prototyping.
Features
■ ^{PowerWise® step-down controller}
■ ^{6V to 42V Wide input voltage range}
■ ^{Fixed output voltage of 3.3V}
■ ^{Fixed switching frequencies of 250 kHz/500 kHz/750 kHz}
■ ^{No loop compensation required}
■ ^{Fully WEBENCH® enabled}
■ ^{Low external component count}
■ ^{Constant On-Time control}
■ ^{Ultra-Fast transient response}
■ ^{Stable with low ESR capacitors}
■ ^{Output voltage pre-bias startup}
■ ^{Valley current limit}
■ ^{Programmable soft-start}
Typical Applications
■ ^Telecom
■ ^{Networking Equipment}
■ ^Routers
■ ^{Security Surveillance}
■ ^{Power Modules}
Typical Application
SIMPLE SWITCHER® is a registered trademark of National Semiconductor Corporation
© 2009 National Semiconductor Corporation 300532
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