Power Management Usage Trends

KMO

Power Management Usage Trends [Copy link]

The complexity of designing the power management portion of many applications has increased significantly in recent years. Today's systems typically require 10 or more different power management ICs that provide not only multiple voltages (with widely varying power levels) but also multiple system support functions. The power management portion of many systems now greatly affects the total design cost and the time required to develop an application. If designers can consider various options in advance and take advantage of the latest products and design support provided by IC manufacturers, they can improve system performance and reduce overall development time and cost.

Power management requirements vary greatly depending on the end device, but we can better understand the various trends in the market by categorizing applications as either portable powered or wall powered. While many trends impact the application space (lower voltages, higher efficiency, multiple power outlets, etc.), portable systems obviously have very different power requirements than systems powered from an external source.

Providing core power for portable applications

In portable systems, current requirements are low, and efficiency and device size are also very important factors. Battery management challenges are critical, including the ability to quickly, easily and safely charge the battery; in addition to notebook computers, more and more applications can correctly display the remaining battery power. The IC should operate over a wide range of input voltages (the voltage of a lithium-ion battery can vary from 2.6V to 4.2V within its operating range), and efficiency at low and high loads becomes critical.

For many portable applications such as MP3 players, PDAs, and digital cameras, system designers must make trade-offs between cost, size, and battery life. These trade-offs directly affect the choice of power supply and the products that IC manufacturers are developing. The lowest cost, easiest to use, and smallest solution will obviously use an LDO regulator, but its weakness is that it is not very efficient. If the current load is high and the power consumption is very large (such as processor and logic power supplies), and the battery voltage needs to be "boosted" (such as required for display backlighting), then a switching regulator is needed.

The portable market has also greatly promoted the packaging trend - devices are getting smaller and smaller. Two new packaging technologies are popular in portable systems, namely plastic leadless chip carriers (QFN or MLP) and WSP (wafer scale) packaging. Plastic leadless chip carriers are a packaging technology that does not use external leads. Compared with traditional packaging, it not only reduces the volume by about 50%, but also has good heat dissipation performance. WSP (or CSP, chip scale packaging) does not use any packaging, but once processed, the chip can be directly soldered on the board, which further saves space than the leadless chip carrier method. Figure 1 shows an example of how integrated functions can be packaged in a small MLP package.

Figure 1. bqTINY in MLP package

Figure 2 shows a large number of components in a typical portable application, and it is clear that they can be integrated. IC manufacturers are introducing new products that combine multiple power functions on the same IC.

Figure 2: A typical portable system has many power management blocks

Providing core power for wall power applications

Systems connected to external power supplies are increasingly moving to distributed power buses. Driven by the large computer and telecommunications markets, where systems include many ICs such as FPGAs, ASICs, and digital signal processors, which are powered from multiple and often very different power rails, the current trend is to generate a single voltage bus (such as 5V) and then power various loads (such as 1.8V, 1.5V, etc.) from this bus through "point-of-load" power supplies. In many of these applications, loads often exceed 20A, which presents a technical challenge to power designers. Multiphase converters are increasingly being used in these applications that require higher currents. With the increase in current, there is a new discussion about the voltage selected for the distributed bus - the higher the voltage, the higher the overall system efficiency and the lower the overall system cost. If the voltage rises too high, the power supply design becomes very complex. Many applications are targeting 12V in the future, but in theory, a lower voltage (such as 8V) may be the best solution.

Of course, wall power system designers have another advantage over portable designers in that they don’t have to design a power supply at all—they can just buy one. Many systems that use a 48V bus voltage use a power module or brick to generate the lower voltages required by the system. There are many Vin/Vout/Iout combinations available, often in standard footprints, and newer products integrate multiple outputs on a single package, further simplifying the design. Even if the decision is made to use a module over a discrete solution, there is still an opportunity to save cost by using an alternate power architecture. By replacing multiple 48V isolated bricks (each for a different supply voltage) with a single isolated brick, which is then paired with multiple low-cost non-isolated modules (discrete solutions), we can significantly reduce costs without increasing design complexity (see Figure 3).

Figure 3: Multiple 48V supplies can be replaced with one 48V block, which can then be paired with several non-isolated modules to save costs.

From a BOM perspective, the lowest cost solution is clearly to design your own power supply. To address this need, IC manufacturers are developing a host of new products that combine higher performance with greater integration, while also working to make them more convenient and easy to use. For non-isolated designs, it is usually much cheaper to buy one than to design one. Although the cost savings are greater, it is also much more complex to design a separate one, requiring an experienced (and dedicated) development team. Many OEMs are making this investment and reaping significant cost savings.

Leverage IC supplier expertise

The different trends in manufacturing end devices combined with the technology used in their chips have created a large and rapidly growing power management market that is well served by new ICs. Before starting a new project, design engineers should review the latest power management ICs from different manufacturers and may find that a new device can better meet the application requirements.

In many organizations, the engineers responsible for designing the power management part are not power designers, but system designers, and therefore face challenges in all aspects of the design. Due to the trend of "system designers" replacing "power designers", many IC manufacturers have invested a lot of resources in all aspects that can provide application support for their products. Making ICs as convenient and easy to use as possible is becoming the key to leading in this market. Many devices now have detailed application accessories and evaluation boards, and providing software tools is a new trend. The software will meet the key requirements of engineers for the power management part of the system and recommend solutions and BOMs based on a general component database. These tools will eventually become a useful design assistant for designers, regardless of their experience, and can reduce design time and risk (see Figure 4).

Figure 4: Software tools reduce development time.