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 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.

Typical Application *click for larger image	Block Diagram *click for larger image
Typical Performance *click for larger image

Parameters Values Output Current 1250 mA Input Min Voltage 8 Volt Input Max Voltage 40 Volt Output Min 2.5 Volt Output Max 37 Volt Frequency Min Undefined kHz Frequency Max 1300 kHz Efficiency (peak) 94.5 % On/Off Pin Yes PowerGood / Error Flag No SoftStart Yes Sync Pin No Inverting Yes Flyback No RegType Switching Regulator Temperature Min -40 deg C Temperature Max 125 deg C Adjustable Output Yes Adj Switch Frequency Yes PWM Mode Constant on-time Topology Buck Special Features No compensation required; ultra-fast transient response Step-Down Yes Multiple Output Capability No Output Power Undefined Watt Output Voltage Undefined Volt Output Range 2.5V to 37V Switching Frequency 1300 kHz Feedback Voltage 2.5 Volt Regulator Family Undefined Automotive Yes Synchronous Rectification No

Datasheets

Title		Size	Date	Other Language
	LM34914 Ultra Small 1.25A Step-Down Switching Regulator with Intelligent Current Limit	328 Kbytes	20-Dec-07

Application Notes

Title		Size	Date	Other Language
	AN-1549: Application Note 1549 LM34914 Evaluation Board	319 Kbytes	17-Mar-07

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM34914SD/NOPB LM34914SD RoHS Status	LLP	Full production Lead Time: 6 weeks	Distributor Region Qty ARROW Worldwide 1780 AVNET-EM Worldwide 1000 DIGI-KEY Worldwide 6258 MOUSER Worldwide 925 RS COMPONENTS Worldwide 20 TAYLOR Americas 1780	$1.35 each at 1K+ pcs	reel of 1000
LM34914SDX/NOPB LM34914SDX RoHS Status	LLP	Full production Lead Time: 6 weeks	Distributor Region Qty DIGI-KEY Worldwide 0	$1.35 each at 1K+ pcs	reel of 4500

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM34914.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM34914 is located at RoHS Status.

Part Number(s) (NSID)	Description	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM34914EVAL	Ultra Small 1.25A Step-Down Switching Regulator with Intelligent Current Limit	Full production	Distributor Region Qty DIGI-KEY Worldwide 0 MOUSER Worldwide 1	$31.50 each	1
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-line is reduced when in current limit Integrated start-up regulator No loop compensation Ultra-Fast transient response Maximum Switching frequency: 1.3MHz Operating frequency remains nearly constant with load current and input voltage variations Programmable soft-start Precision internal reference Adjustable output voltage Thermal shutdown Applications: High Efficiency Point-Of-Load (POL) Regulator Non-Isolated Buck Regulator Secondary High Voltage Post Regulator Contents: A LM34914 Fully Assembled Evaluation Board A LM34914 Datasheet A LM34914 Evaluation Board Appnote

National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C1) and Banned Substances and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at: www.national.com/en/packaging/greennopb.html. Lead free products are RoHS compliant.

Lead Free product status is available through the search tool located here

Part Number(s) (NSID)	Weight (milligrams)	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM34914SD/NOPB LM34914SD	21.112 21.182	LLP	10	1 1	260 260	Detail	N/A	N/A	ZXYTT 34914
LM34914SDX/NOPB LM34914SDX	21.112 21.182	LLP	10	1 1	260 260	Detail	N/A	N/A	ZXYTT 34914

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM34914.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM34914 is located at RoHS Status.

Design Tools

Title	Size	Date
LM34914 Quick Start Calculator

CAD Symbols and Models N/A

Models N/A

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM34914SD	ABCD150	0	42680	0	0	6394000	1	1814314958
LM34914SDX	ABCD150	0	42680	0	0	6394000	1	1814314958

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

For more information on Reliability Metrics, please click here.

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM34914.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM34914 is located at RoHS Status.