Date: 22/10/2008
Synchronous buck controllers & MOSFET selection tool for controller designs
National Semiconductor introduced a new family of synchronous buck controllers and the end-to-end MOSFET selection tool to simplify switching controller designs.
This new PowerWise SIMPLE SWITCHER controller family includes four synchronous buck controllers, LM3150, LM3151, LM3152 and LM3153 for communications and industrial systems. These controllers require minimal external components, which simplify the design process and reduce the size.
The new synchronous buck controllers hold features like:
1. The LM3150 features an Programmable switching frequency up to 1 MHz and adjustable output voltage down to 0.6V
2. The LM3151, LM3152 and LM3153 feature a range of fixed frequencies (250 kHz, 500 kHz and 750 kHz, respectively) along with a fixed 3.3V output voltage.
3. Input voltages for all these controllers range from 6V to 42V with output current capability up to 12A.
4. They employ a constant-on-time (COT) control topology that eliminates the need for an external compensation network.
5. The emulated ripple-mode technology allows for the use of low equivalent-series-resistance (ESR) output capacitors, which further reduces system size, complexity and output voltage ripple.
Key features of the new MOSFET Selection Tool for Controller Designs are:
1. The new MOSFET selection tool "WEBENCH" provides end-to-end support for switching controller designs, including MOSFET selection, MOSFET optimization and design simulation.
2. The tool includes technical data of MOSFETs, allowing the designer to sort and select MOSFETs by thermal parameters & power dissipation.
3. Optimization graphs and charts offer views of the impact of optimizing the design for efficiency or footprint over various operating ranges.
4. The designer can analyze power dissipation of the MOSFETs at different frequencies, efficiencies and footprints as well as over the load current and input voltage operating ranges.
5. Once the MOSFETs are selected and optimized, the WEBENCH design environment provides electrical simulation of the circuit's dynamic behavior in both frequency and time domains.
6. The designer can then run thermal simulations of the complete solution, including the MOSFETs, to analyze thermal characteristics of the design.
Availability: All the four devices are currently in mass production.
Six additional SIMPLE SWITCHER controllers featuring fixed output voltages of 2.5V and 5V will be available in the first quarter of 2009.
Packaging: 14-pin thermally enhanced TSSOP package
Pricing: $2.30 each for LM3150, LM3151 & LM3152 in 1K-unit quantities
$2.22 each for LM3153 in 1K-unit quantities