August 26, 2009
LM3151/LM3152/LM3153
SIMPLE SWITCHER® CONTROLLER, High Input Voltage
Synchronous Step-Down
General Description
Features
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.
PowerWise® step-down controller
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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
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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.
Typical Applications
Telecom
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Networking Equipment
Routers
Security Surveillance
Power Modules
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Typical Application
30053201
SIMPLE SWITCHER® is a registered trademark of National Semiconductor Corporation
© 2009 National Semiconductor Corporation
300532
www.national.com