Features • Integrated N-Channel buck switch • Integrated start-up regulator • Input Voltage Range: 8V to 40V • No loop compensation required • Ultra-Fast transient response • Operating frequency remains constant with load current and input voltage • Maximum switching frequency: 2.0 MHz • Maximum Duty Cycle Limited During Start-Up • Adjustable output voltage • Valley Current Limit At 0.64A • Precision internal reference • Low bias current • Highly efficient operation • Thermal shutdown Description The LM34919 Step Down Switching Regulator features all of the functions needed to implement a low cost, efficient, buck bias regulator capable of supplying 0.6A to the load. This buck regulator contains an N-Channel Buck Switch, and is available in a micro SMD package. The constant on-time 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 lockout, thermal shutdown, gate drive under-voltage lockout, and maximum duty cycle limiter.

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

Datasheet

Title		Size	Date	Other Language
	LM34919 Ultra Small 40V, 600 mA Constant On-Time Buck Switching Regulator	377 Kbytes	2-Jun-08

Featured Application Notes

Title		Size	Date	Other Language
	AN-1650: Application Note 1650 LM34919 Evaluation Board	338 Kbytes	8-Jun-07	中文

More Application Notes

Title		Size	Date	Other Language
	AN-1349: Application Note 1349 LM34910 Evaluation Board	562 Kbytes	18-Nov-04
	AN-1549: Application Note 1549 LM34914 Evaluation Board	319 Kbytes	17-Mar-07
	AN-1601: Application Note 1601 LM34917A Evaluation Board	1142 Kbytes	10-Apr-08

Design Tools

Title	Size	Date
LM34919 Quick Start Calculator	365 Kbytes	3-Aug-2009

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM34919ATL	ABCD150	0	34175	0	0	4234000	1	1201409060
LM34919ATLX	ABCD150	0	34175	0	0	4234000	1	1201409060
LM34919TL	ABCD150	0	34175	0	0	4234000	1	1201409060
LM34919TLX	ABCD150	0	34175	0	0	4234000	1	1201409060

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.

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