11 Power Module Myths

This article is part of TechXchange: FoodDesign

What you will learn:

  • Role of power modules in current and future switching power supplies.
  • How power modules can save you design time.
  • Differences between module and discrete implementations.

“I love over-complicating my design process” – never said any engineer. Although never intentional, the number of hurdles that arise in the process of selecting a power management solution can be overwhelming.

Perhaps surprisingly, power modules could be the semiconductor industry’s answer to some lingering problems. With advanced component integration, optimization and performance, the modules offer a powerful solution that makes the design process easier than ever.

But, alas, the value of a power module is subject to the same scrutiny as a certain handheld device circa 2007, introduced by a certain turtleneck CEO, who could surf the web, gamble a million songs and call people. Some skeptics still see mods as inflexible, while others think they’re just a fad. Join me as I examine the general cries and claims as I address 11 common power module myths.

1. Power modules don’t save much time. You know which components will work best for your design.

Engineers all know that feeling of combing through spec sheet after spec sheet to no avail. We know the feeling of seeing a 10 week time frame on resistance that had 100 units in stock the day before. We know the feeling of running our “final” subsystem tests, only to find that a resistor hasn’t been soldered in correctly.

Fortunately, the power module manufacturing process itself eliminates most of these headaches. Using a power module greatly reduces the task of finding components and running simulations to characterize your power stage, leaving you free to spend time solving the problems that matter most to you.

2. Power modules only apply to more generic use cases. Discrete solutions are always better because you can optimize them for any use case.

A fully integrated solution is not the same as a solution that aims to please everyone. In fact, part of what makes power modules so easy to use is that they are often derived from discrete solutions that already address specific use cases. For example, if your preferred discrete solution is optimized for low noise, fast transient response, or extended operating temperature, there is likely a power supply module that meets a very similar specification.

Additionally, many modules come in pin-to-pin families that span specific output current or voltage ranges. For example, the TPSM41615 and TPSM41625 power modules are 15 and 25 A stackable solutions that share the same footprint, so they cover a current range of 15 to 50 A. (Fig.1). Rather than being stuck with a one-size-fits-all generic solution, you have the flexibility to choose a device that suits your system requirements and avoid a major redesign if anything changes.

3. Power modules have no inherent advantage outside of integration. Discrete solutions don’t lock you into arbitrary optimization or require the use of certain passives.

When you choose to design with power modules, you can have peace of mind knowing that the solution of your choice was hand-crafted by the industry’s top experts in power, packaging, and layout. Beyond the datasheet, power module manufacturers also provide designers with simulation tools and characterization data. By selecting a power module, you have access to a fully characterized power supply, which means you don’t have to spend extra time determining if a device is right for you.

Using a discrete converter would be like involving a student driver in a Formula 1 race. Why jeopardize crossing the finish line when a module guarantees you a place on the podium?

4. Power modules use components that are not qualified for more severe applications.

If your power supply soars 30,000 feet above ground, you’ll want to make sure the air temperature isn’t causing a malfunction. Similarly, in an operating room, interference from a power supply can cause noise or distortion in the outputs of imaging equipment.

To mitigate this, you can use a discrete converter that works with an extended temperature range or a converter that is compliant with the International Special Committee on Radio Disturbances (CISPR). However, this still requires selecting and sourcing qualified components to meet those specifications.

Fortunately, the power modules are pre-validated to meet these requirements, giving you an out-of-the-box solution out of the box. For applications sensitive to electromagnetic interference (EMI), EMI-tested power modules like the TPSM63606 include built-in passive components that have been designed to meet stringent requirements.

5. Power modules are expensive.

It’s easy to look at something smaller and more efficient and think about the associated price, or assume ease of use comes at a premium. Fortunately, the modules are not laptops or smartphones.

First, the nominal price gap between power modules and discrete solutions is slowly reaching parity. When you look at the cost of sourcing, qualifying, and disposing of passive components that would already be built into a module, it becomes clear that the cost of doing so, in addition to component selection and sourcing external ones, comes pretty close to (and in some cases even exceeds) the cost of simply choosing a power supply in the first place.

Another often overlooked factor is the potential cost of things going wrong. The “premium” associated with power modules is nominal compared to the cost of recall, requalification, retesting, etc.

6. Power supply modules will not help you save board space.

Power modules can be smaller than a discrete solution in embedded packages, which embeds a chip directly into a printed circuit board (PCB) substrate, as shown in Figure 2, thus allowing the actual substrate area to house external components such as the inductor. This integration effectively removes the converter step from the overall XY calculation, resulting in a solution size that is impossible to replicate using a discrete solution alone.

7. Power modules are too high.

A discrete solution alone is almost never the source of a significant increase in solution height. In fact, most height increases are actually attributable to the inductor, as it is almost always the tallest component in your power management system. Since power modules are typically optimized for solution size, efficiency, and height, there is a general guarantee that you can expect a module height as short, or even shorter, than a discrete implementation.

8. Power modules are not optimized for efficiency because power module manufacturers do not consider factors other than inductor selection.

It’s understandable to think that because the inductor is already pre-selected and built-in, a power module trades high efficiency for ease of use. On the contrary, power modules are designed to provide the most efficient solution with the added benefit of integration.

Since discrete efficiency curves often rely on field-effect transistor switching, heat dissipation, and heuristic external component selection, overall efficiency actually has several contributing factors. Power modules work to take these external factors (which often confuse even the best designers) and provide the simplest possible solution while maintaining or even exceeding the efficiency standards you expect.

9. Compared to leading discrete solutions, power modules are a few generations behind.

Integrated circuit (IC) manufacturers are always looking for ways to simplify the process of designing and manufacturing electronics. As I mentioned earlier, industry-leading discrete solutions often serve as the inspiration for the latest and greatest in power module solutions.

Beyond the chip, however, IC designers are also pushing the boundaries of packaging, component placement, and process technology. The latest and greatest features, typically only available through discrete converters, are now available in the smallest, easiest to use, and most efficient form factor possible.

10. You don’t need power modules: You can easily replicate the power module design yourself.

Looking at the size of the solution in length and width, the adventurous designer might be inclined to think that he can come up with an arrangement of components to create a final power supply that saves as much board space as humanly possible. . But the construction of many modules is not easily reproducible by hand.

An example of this is how some modules have components embedded directly into the substrate on which the chip sits. Another example is the overmolding of die and embedded components to improve their adhesion to the lead frame. These manufacturing innovations are just a few of the ways packaging engineers can shave millimeters off your design.

11. Power modules are just a fad.

Although I don’t have access to a crystal ball, one thing remains clear: the design challenges are only going to get harder (and take longer) to solve as the requirements become more stringent. Every day, more power supply designers are turning to the use of power supply modules because they reduce size, provide more optimized efficiency, and offer the richest feature sets. The resulting benefits greatly outweigh the risks associated with venturing out on your own in search of the right power solution.

Additionally, semiconductor manufacturers continuously monitor power trends and application requirements, all with the goal of reducing the frequency of obstacles in your design and helping you get your product to market faster than ever before. .

Conclusion

You demanded an efficient, robust and easy-to-use power solution – the industry delivered. By implementing a power module, you effectively incorporate the expertise of the industry’s best into your design. While recognizing that there is never a one-size-fits-all power supply solution, I hope that by reading this article you can see that modules have a place in your current and future switching power supplies.

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