■ Power supply architecture design tool plays an important role in the system development process

Tools for designing power supply architectures are less widely used than computational and simulation tools, but they play a very important role in the development of power supply systems for electrical circuits. These tools serve as an early step in the power supply development process, laying the foundation for building an optimal power supply architecture.

■ Preface

Currently, there are various development tools available on the market that reduce the burden of tedious work on developers when developing power supply devices.

LTspice®, a widely known simulation tool from Analog Devices, Inc. (ADI), is one of them.

This tool can be used to simulate power conversion circuits, simulating various voltage and current waveforms to improve circuit design and tune it closer to specific requirements.

ADI also offers computational tools such as LTpowerCAD®, which, unlike LTspice, is designed for computation rather than simulation.

The circuit is calculated and optimized by considering various specifications such as input voltage range, output voltage, load current, and output voltage ripple.

In this process, appropriate power converter ICs and external passive components are proposed.

Therefore, tools such as LTpowerCAD are often run prior to circuit simulations utilizing LTspice.

Another important aspect in power supply development is defining the power supply architecture, or creating the power tree.

To fully power any system, two or more power converters are typically required.

This is because many different voltages are often required in a single system.

There are many different ways to do this. The differences between architectures can be calculated and beautifully represented using a power supply architecture tool such as ADI's LTpowerPlanner®.


Figure 1 shows the interface of LTpowerPlanner along with a representation of the power supply architecture using a 24 V input.

From this, various supply voltages and currents are generated. Different functional blocks can be easily added and connected via connecting wires.

You can define the efficiency of each power conversion by clicking on one of these blocks.

Given these inputs, LTpowerPlanner can perform overall calculations for the entire power conversion device architecture. The overall efficiency of the architecture shown in Figure 1 is 91.6%.


Architectural tools such as LTpowerPlanner enable users to compare different power conversion architectures.

Figure 2 shows a solution with the same specifications as Figure 1, but with a different structure. We can now compare this second solution with the first. Here a linear regulator (LDO) is used to generate a 1.2 V rail from a 2.8 V rail. This solution with a linear regulator is more cost-effective than converter 4 in Figure 1.

Another change to the solution depicted in Figure 2 is that the 3.3 V voltage is generated from the 5 V DC link voltage rather than from the 24 V of converter 2.

Figures 1 and 2 show not only the architecture but also the calculated efficiencies. The overall architecture efficiency of Figure 2 is only 86.3%, which is 5.3% lower than the solution in Figure 1.

When deciding which architecture is best, users can compare the cost of each solution, the efficiency performance of the overall architecture, and the size of each solution. These considerations are difficult to achieve without a sketching tool like LTpowerPlanner.


LTpowerPlanner can be used as a standalone tool to create power supply architectures (Figure 3).

This tool is available within LTpowerCAD, which is available for free download from the ADI website.

LTpowerPlanner can be accessed from the 'System Design' section with a blue background.

The LTpowerPlanner tool is intended to provide a clear overview of various power supply architectures.

Additionally, the built-in computational capabilities can be leveraged to determine which architecture is more efficient.

■ Optimization of power management architecture

The first step within the power management tool chain is to optimize the power management architecture.

ADI's LTpowerPlanner provides a useful tool for this. This tool can be used to diagram power trees in different configurations and compare them.

LTpowerPlanner also includes an efficiency calculation feature that provides valuable information about each available architecture, allowing you to quickly select the optimal architecture.

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■ About the Author

Frederik Dostal is a power management expert with over 20 years of experience in the industry. He graduated from the University of Erlangen in Germany with a degree in microelectronics and joined National Semiconductor (NS) in 2001 where he gained extensive experience implementing power management solutions for customer projects as a FAE. While at NS he worked in Phoenix, Arizona for four years as an applications engineer working on switch mode power supplies (SMPS). He joined Analog Devices in 2009 and has since held various positions in product lines and European technical support. He is currently based in Munich, ADI as a power management expert with extensive design and application knowledge.