free analog design software

Texas Instruments offers both a selector guide and the downloadable Tina-TI Spice program. TI developed Tina-TI Spice in partnership with DesignSoft, which offers the Tina simulator. In addition, TI offers the downloadable FilterPro filter designer, a mathematical-analysis program that indicates the theoretical performance of filters using characteristics about their passive components and amplifiers. TI also offers the online or downloadable SwitcherPro switching-power-supply designer . With the tool, engineers who are not working online can continue to design their circuits. Both the downloadable and the online versions of the tool offer approximately the same speed, according to Rich Nowakowski, a TI product-marketing engineer.

To complement this power-supply-design program, the company also offers the downloadable ADCPro, ClockPro, and MDACBufferPro programs for multiplying DACs and publishes a variety of simple online tools to help you design electronic systems. For example, the JavaScript-powered, four-band-color-coded calculator illustrates a conventional through-hole resistor and lets you identify the color bands using drop-down menus. The program then gives you the value of the resistor with that color code.

TI has also developed dozens of online calculators to help you with everything from choosing two standard resistors to achieve a user-specified voltage-divider value to more complicated tasks, such as calculating the component values to design a single-ended to fully differential amplifier circuit. Rounding out TI’s offerings are downloadable tools for calculating ISM (industrial/scientific/medical)-band loop filters and programs for selecting the component values for buck-switching regulators.

Another successful analog company offering online tools, Analog Devices, has teamed up with test-and-measurement powerhouse National Instruments to create the ADIsim online-design program to help you design op-amp and switching-power-supply circuits . Invoking two levels of calculations, the tool helps you select parts and then calculates the performance of a circuit from specific design equations. Once you are happy with this approximation, you can invoke a full Spice simulation that uses the Multisim simulator from National Instruments subsidiary Electronics Workbench. Analog Devices also lets you download a free version of Multisim that works with the company’s parts. The company also offers the ADIsimDAC DAC-design tool and ADIsimRF, the downloadable version of which can help you calculate RF parameters, such as gain, noise figure, and power consumption. Another downloadable tool, ADIsimPLL, provides design help and evaluation for PLL (phase-locked-loop) design.

New to the online-simulation-tool-provider list is analog stalwart Maxim Integrated Products. Although the company has only recently begun to provide powerful online tools, it has made up for its late entry by getting many things right. As with most analog-semiconductor manufacturers, Maxim prefaced its online-design-tool development with an online-parametric-selection guide. The tool recalculates the screen and changes with the subsequent selection sliders whenever you make a selection, meaning that you will always have choices, according to Erin Mannas, the company’s Web-content engineer.

Maxim also now provides the EE-Sim online-design environment , which the company envisions as a further step in product selection. Once you select a part that the software supports, you receive a link to start the EE-Sim application. As of March, the environment supported only four parts, but Maxim plans this year to add an array of supported parts. Rather than use a classic Spice engine, Maxim uses SIMetrix Technologies’ Simplis. This package does not do matrix math in an iterative fashion like Spice. Instead, the models are piecewise-linear approximations of diode curves and transistor characteristics. The simulations run at high speed, more than making up for the small sacrifice in accuracy. According to Eric Schlaepfer, Maxim’s strategic-application engineer, the program reaches results in 10 times less time than does a classic Spice program. You can download the program so you can work on simulations without hooking up to the Web. Like TI, Maxim offers a variety of simple design calculators, such as a tool for creating the data to drive a pattern generator for making waveforms.

The broad-market analog companies are not the only ones that provide you with design tools. Microchip, for example, offers MAPS (Microchip advanced parts selector), and Power Integrations offers the downloadable PIExpert tool to help you design switching power supplies, including high-power resonant supplies that also have PFC (power-factor correction). Fairchild offers the FETBench online program, which it developed with Transim Technology and which Intersil and NXP also employ. The FETBench environment can help you choose FETs; then, you can use Fairchild’s Ansys-powered WebSIMThermal application to see the thermal performance of the part in a specified environment of board size, airflow, and part arrangement . Fairchild even lets you define your own parts so you can use this tool for any PCB thermal problem. Intersil offers the iSim Web tool, which helps you design and simulate power-supply and op-amp circuits . A downloadable version lets you capture schematics and evaluate circuit performance.

International Rectifier offers a suite of online-design tools that can help you design PFC circuits and simple buck regulators. These tools lack the ability to perform full thermal analysis, but they can save time when you need to design this type of circuit. When you hit the “analyze” button, the application generates a PDF file of your design that you can submit to your manager or use in a design review. International Rectifier also offers calculators for motor control and downloadable software to help you design lighting ballasts, along with bus-converter-design assistants that provide a selection of parts for various converter topologies, such as full-bridge, half-bridge, and forward converters. The company’s Web site offers design support for the iMotion motor-control engine, which lets you develop custom control algorithms.