1FEATURES
234• 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 short•
Telecom pre•
Networking Equipment
• Routers
• Security Surveillance
• Power Modules

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 features switching
frequencies of 250 kHz, 500 kHz, and 750 kHz. The
synchronous architecture provides for highly efficient
designs. The LM3151/2/3 controller employs a
Constant On-Time (COT) architecture with a
proprietary Emulated Ripple 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)
regulation architecture allows for fast transient
response and requires no loop compensation, which
reduces external component count and reduces
design complexity.
Fault protection features such as thermal shutdown,
under-voltage lockout, over-voltage protection, short•
circuit protection, 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 TI’s
WEBENCH online design 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, electrical
simulation, thermal simulation, and Build-It boards for
prototyping.