Today’s electronics systems require an increasing number of power rails and supply solutions, with the load range from a few mA for standby supply to over 100A for ASIC or FPGA core voltage regulators. It is important to have the appropriate solutions for the targeted applications and meet specified performance requirements, such as high efficiency, high reliability, tight printed circuit board (PCB) space, accurate output regulation, fast transient response, and low solution cost. Power management design, especially embedded switching mode supply design, is becoming a more frequent and challenging task for system designers, who may or may not have strong power supply backgrounds. Linear Technology offers a pair of tools, LTspice IV and LTpowerCAD II to help designers tackle these challenges.
The LTspice schematic capture and simulation tool offers a powerful aid to system designers in understanding the operation of an analog circuit and visualizing its waveforms and dynamic performance. LTspice is especially helpful in the following situations:
- When a user needs to develop a new circuit solution or unfamiliar supply topology
- If a user needs to understand or evaluate a new LTC product
- When a user needs to check a circuit’s dynamic behaviors and performances
However, because it is a general purpose simulation-oriented tool instead of design-oriented tool, LTspice has some limitations:
- For an inexperienced supply designer, the simulation waveforms do not provide sufficient explanations nor guide him with component selection and design trade-offs.
- For an experienced supply designers working on a familiar topology/solution with many repetitive designs, simulation may not be a necessary or productive design method. Instead, he really needs a spreadsheet tool to quickly calculate power supply parameters/values and estimate its performance.
- The LTspice simulation does not offer a detailed supply efficiency estimation and loss breakdown analysis, which can be very useful to select power components.
- LTspice does not offer a convenient , fast loop compensation design method for a switching mode supply. The user needs to either build his own small signal circuit model or do repetitive time-domain simulations with sinusoidal perturbation waveforms, which can be challenging and time consuming.
As a complement to the LTspice simulation tool, LTpowerCAD is a design-oriented tool. As a complete power supply design tool, it can significantly ease the burden of power supply solution selection and design, minimize design risk and improve design productivity. LTpowerCAD guides users throughout the entire supply circuit design process by helping users to:
- Search for suitable LTC solutions according to supply specifications
- Select and optimize power stage component values with suggestions and warnings
- Estimate power supply efficiency and loss breakdown
- Design feedback loop compensation with real time loop and transfer function bode plot
- Optimize load transient performance
- Export design results to LTspice circuit for further simulation
LTpowerCAD and its supply circuit models are developed by some very experienced power supply designers – Linear Technology’s power applications engineers. We are trying to share our power electronics knowledge and power supply design skills with all users. With accurate, bench-verified circuit models and step-by-step design procedures, the program will help system designers to save design time and improve their supply design quality.
The LTpowerCAD design tool was released in June of 2013, with close to 200 Linear Technology power products modeled in the program. Since then, we have been improving its features and adding more and more parts to the program.