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 under-voltage lock-out, thermal shutdown, gate drive under-voltage lock-out, and maximum duty cycle limit.

• 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