1FEATURES
2• Input Voltage Range: 8V to 40V
• Integrated N-Channel Buck Switch
• Valley Current Limit Varies with VIN and VOUT
to Reduce Excessive Inductor Current
• On-time is Reduced when in Current Limit
• Integrated Start-Up Regulator
• No Loop Compensation Required
• Ultra-Fast Transient Response
• Maximum Switching Frequency: 1.3 MHz
• Operating Frequency Remains Nearly
Constant with Load Current and Input Voltage
Variations
• Programmable Soft-Start
• Precision Internal Reference
• Adjustable Output Voltage
• Thermal Shutdown

underTYPICAL
APPLICATIONS
• High Efficiency Point-Of-Load (POL) Regulator
• Non-Isolated Buck Regulator
• Secondary High Voltage Post Regulator

DESCRIPTION
The LM34914 Step-Down Switching Regulator
features all the functions needed to implement a low
cost, efficient, buck bias regulator capable of
supplying at least 1.25A to the load. To reduce
excessive switch current due to the possibility of a
saturating inductor the valley current limit threshold
changes with input and output voltages, and the on-
time is reduced when current limit is detected. This
buck regulator contains a 44V N-Channel Buck
Switch, and is available in the thermally enhanced 3
mm x 3 mm WSON-10 package. The feedback regulation scheme requires no loop compensation,
results in fast load transient response, and simplifies
circuit implementation. The operating frequency
remains constant with line and load variations due to
the inverse relationship between the input voltage
and the on-time. The valley current limit results in a
smooth transition from constant voltage to constant
current mode when current limit is detected, reducing
the frequency and output voltage, without the use of
foldback. Additional features include: VCC underTYPICAL
voltage lock-out, thermal shutdown, gate drive undervoltage
lock-out, and maximum duty cycle limit.

Package
• WSON-10 (3 mm x 3mm)
• Exposed Thermal Pad For Improved Heat
Dissipation