The better you can plan, simulate, and assess your design, the shorter and less frustrating the design cycle will be: that's no great secret. To better meet the challenge of power-supply design, National Semiconductor has added new features to its well-established Webench design tool and environment, to provide more capabilities and tradeoff/optimization insight.
Webench now includes facilities for detailed bill of materials (BOM) charts (which can include both ICs and discrete devices from outside vendors); many analytical graphs showing parameters including efficiency, dissipation, and footprint versus factors such as frequency; Bode plots for loop dynamics and stability, electrical performance under start-up and load or line transient conditions, and more. In addition to the switching IC or controller, Webench addresses the degrees of freedom and factors the designer must juggle, including:
- Electrical simulation
- Macro and local dissipation ,and overall efficiency
- MOSFET selection
- Passive component selection
- Capacitors and ESR
- RC compensation networks
- Vin and Vout, Iout
- Stability and load/line transept response
- Output accuracy and ripple
- And, of course, cost
I was especially impressed with the thermal simulation and modeling capabilities of the enhanced Webench. This is an area where standard electrical simulation is insufficient, of course. The thermal simulation in Webench--based on detailed thermal models of the ICs, passive and discrete components, and even heat sinks and copper paths and thickness, provides a very realistic view of the overall design's thermal situation as well as localized hot spots, which can be detrimental even when overall load is within limits.
The Webench tool is online and free; registration is required. For more information, click here.