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