PowerWise Buck Regulators Supply up to 1.2A and Feature Intelligent Current Limiting and Over-Voltage Protection
National's new LM34917A and LM34919 feature programmable switching frequency up to 2 MHz. The products integrate MOSFET switches to reduce system component count, and a high switching frequency enables use of ultra-small inductors and capacitors for very small solution size.
The LM34917A and LM34919 utilize a constant on-time (COT) control scheme, which requires no loop compensation. The regulators are well-suited for use in applications that require high-input voltage regulations such as MP3 players utilizing Firewire connectivity (IEEE1394) as well as MP3 players or auxiliary power adapters with direct connection to a 12V (universal) automotive power outlet where transient protection requirements can exceed 40V.
The LM34917A and LM34919 feature peak efficiency equal to or greater than 90 percent, positioning it among National's PowerWise(R) family of energy-efficient products. The products feature ultra-small micro SMD packaging and extend National's buck regulator product line which includes the LM2694, LM34910 and LM34914 buck regulators offered in LLP(R) packaging.
Key Features and Benefits of the LM34917A and LM34919 Buck Regulators
The LM34917A and LM34919 step-down switching regulators feature all of the functions needed to implement a low-cost, efficient buck bias regulator.
The LM34917A buck regulator supplies up to 1.25A to the load. It contains an N-Channel MOSFET buck switch and is available in a 12-pin, 2 mm by 2.3 mm micro SMD package. In addition to no loop compensation, the COT feedback regulation scheme also 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 without foldback when the output is overloaded. Additional features include VCC under-voltage lockout, thermal shutdown, gate drive under-voltage lockout and maximum duty cycle limiter.
The LM34919 buck regulator supplies up to 0.6A to the load and features the constant on-time feedback regulation scheme of the LM34917A. The LM34919 is offered in a 10-pin, 1.5 mm by 2 mm micro SMD package.
For more information on the LM34917A and LM34919 or to order samples and an evaluation board, visit http://www.national.com/pf/LM/LM34917A.html and http://www.national.com/pf/LM/LM34919.html.
Packaging and Pricing
Available now, the LM34917A is priced at $1.35 each and the LM34919 is priced at $1.05 each. All prices are in 1,000-unit quantities.
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About National's Power Management Products
National solves power management design problems in space- and energy-constrained applications from feature-rich handheld devices through large line-powered systems. From the novice power designer to the power expert, National's products, people and design tools enable customers to design green-powered systems with complex power supplies in the shortest amount of time. High-performance products include switching regulators such as National's flagship SIMPLE SWITCHER(R) family, and application-specific products including white-LED drivers and Power-over-Ethernet controllers. More information about National's power management products is available at http://power.national.com.
About National's PowerWise Brand
National's PowerWise brand reflects the company's energy-efficient product portfolio. It signifies products with outstanding performance-to-power at the component level, as well as products that provide an outstanding, energy-efficient solution when coupled with other National parts. National's PowerWise family of products features energy-efficient power management, operational amplifiers, interface and data conversion products. For more information about National's PowerWise brand, visit: http://www.national.com/powerwise.
About National Semiconductor
National Semiconductor, the industry's premier analog company, creates high-value analog devices and subsystems. National's leading-edge products include power management circuits, display drivers, audio and operational amplifiers, interface products and data conversion solutions. National's key analog markets include wireless handsets, displays, communications infrastructure, medical, automotive, industrial, and test and measurement applications. Headquartered in Santa Clara, Calif., National reported sales of $1.93 billion for fiscal 2007, which ended May 27, 2007. Additional company and product information is available at http://www.national.com.
National Semiconductor, SIMPLE SWITCHER, LLP and PowerWise are registered trademarks of National Semiconductor Corporation. All other brands or product names are trademarks or registered trademarks of their respective holders.
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