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LM34914 Dataheets PDF



Part Number LM34914
Manufacturers National Semiconductor
Logo National Semiconductor
Description Ultra Small 1.25A Step-Down Switching Regulator
Datasheet LM34914 DatasheetLM34914 Datasheet (PDF)

LM34914 Ultra Small 1.25A Step-Down Switching Regulator with Intelligent Current Limit December 20, 2007 LM34914 Ultra Small 1.25A Step-Down Switching Regulator with Intelligent Current Limit General 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 li.

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LM34914 Ultra Small 1.25A Step-Down Switching Regulator with Intelligent Current Limit December 20, 2007 LM34914 Ultra Small 1.25A Step-Down Switching Regulator with Intelligent Current Limit General 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 LLP-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. Features ■ 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 Typical Applications ■ High Efficiency Point-Of-Load (POL) Regulator ■ Non-Isolated Buck Regulator ■ Secondary High Voltage Post Regulator Package ■ LLP-10 (3 mm x 3mm) ■ Exposed Thermal Pad For Improved Heat Dissipation Basic Step Down Regulator © 2007 National Semiconductor Corporation 201973 20197301 www.national.com LM34914 Connection Diagram Ordering Information Order Number Package Type LM34914 SD LM34914 SDX LLP-10 (3x3) LLP-10 (3x3) 20197302 10-Lead LLP NSC Package Drawing SDA10A SDA10A Junction Temperature Range Supplied As −40°C to + 125°C −40°C to + 125°C 1000 Units on Tape and Reel 3500 Units on Tape and Reel Pin Descriptions Pin Number 1 Name SW Description Switching Node 2 BST Boost pin for bootstrap capacitor 3 ISEN Current sense 4 SGND Sense Ground 5 RTN Circuit Ground 6 FB Feedback input from the regulated output 7 SS Softstart 8 RON/SD On-time control and shutdown 9 VCC Output from the startup regulator 10 VIN Input supply voltage EP Exposed Pad Application Information Internally connected to the buck switch source. Co.


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