MILPITAS, CA - May 16, 2001 - Linear Technology has released SwitcherCAD III, a fully functional Spice simulator with schematic capture and waveform display tool, for public distribution. The software's internal enhancements to the Spice code provide optimized transient simulation of complex switching regulator systems on a cycle-by-cycle basis. The simulator can also calculate the circuit efficiency and generate a bill of material for some demo circuits. A full-featured schematic capture system allows easy entry of the circuits. Circuit models are dynamically linked in the schematic for simulation. Components can be easily changed on the schematic page. A waveform viewer can display both the current and voltage of all circuit components. Besides marching waveform, a waveform calculator is also included for data manipulation.
One of the biggest problems in designing high performance switching regulators is obtaining CAD tools for system simulation. While equation-based and continuous time models exist, they do not provide the detail of cycle-by-cycle transient behavior. Some tools have fixed circuits and won't simulate user-designed circuits. Furthermore, most of the tools have a very steep learning curve. With the analog macro models and special convergence control for switching regulators, the SwitcherCAD III can speed up the simulation by a factor of 10 over the traditional method. There is no Spice experience required to exercise the demo circuits, evaluate switching regulator configuration or edit component values. It is all done in minutes on a Windows95Â®/NTÂ® PC. According to Robert Dobkin, Chief Technical Officer of Linear Technology,
"This is a breakthrough in switching regulator simulation. It brings a CAD tool to the desktop for fast evaluation of complicated circuits. Also, the Spice is fully functional and allows other types of circuits to be simulated in a user-friendly environment."
This Spice simulator with schematic capture, comparable to many costly commercial Spice programs, is free from Linear Technology.
Along with the Spice simulation engine are macro models for over 100 switching regulators. This speeds up the initial evaluation of many devices. Circuits and component values of the provided switching regulator circuits can be quickly modified to generate new custom applications. A library of 200 Op Amps are also included in the component library along with other analog and mix-mode building blocks. The enhancement code for this switching regulator simulator was developed entirely within Linear Technology and includes proprietary convergence, time-step control and analog behavioral modeling for fast and accurate Spice simulation.
Figures 1 and 2 show screen captures of the schematic of a switching regulator. The output waveform viewer in figure 2 shows the load regulation and output ripple of this switching regulator. The total simulation time for the load regulation transient was only two minutes on a 700MHz PentiumÂ® III PC. Built into the program is a web update feature allowing new models and program changes to be downloaded automatically through the Internet and installed in the user?s computer.
For a free download of the SwitcherCAD III program, go to www.linear.com/software.