Not long ago, there was a classic cliché discussion in EEWorld's WeChat group about module power supply or discrete devices.
The reason for this is the introduction of an isolated power module MIE1W0505BGLVH from MPS. The product description is as follows: It is an isolated regulated DC/DC power module. It supports input voltage (VIN) applications up to 3V to 5.5V with output power (POUT) up to 1W with excellent load and linearity regulation.
MIE1W0505BGLVH Feedback blocking with capacitive isolation technology eliminates the need for traditional optocouplers and shunt regulators to regulate the output voltage (VOUT). Compared with traditional isolated power modules, the modules are smaller in size and more reliable in operation. MIE1W0505BGLVH also features continuous short-circuit protection (SCP) and over-temperature protection (OTP).
The device is available in a small LGA-12 (4mmx5mm) package.
Some netizens think that this product is very good, after all, it is miniaturized and supports continuous short-circuit protection, and some netizens think that the small package is really good, but their scenarios do not need this aspect very much. Some netizens also think that the price is too expensive, and the price of $1.24 is far more expensive than discrete devices, especially after batch production. However, netizens recognize the cost performance more, not simply compare the price, but also consider the conditions of comprehensive cost performance, the price is only the denominator, and the performance is equally important.
So, it led to today's big discussion, should we use modules or discrete?
Is the power module good?
This discussion is a problem that all engineers have to face to a greater or lesser extent, especially in recent years, with the development of integrated circuit technology, modules are becoming more and more miniaturized and chip-based, so they have more and more advantages, such as ease of design, cost-effectiveness, efficiency and size, higher performance, faster development cycle, simpler PCB, and so on.
In addition, there is a shortage of engineers specializing in power supply design, especially excellent personnel, and many people are not willing to waste too much time to improve the efficiency by 1%. Traditionally, designers have used discrete components to design with relatively simple circuits, but as requirements increase, including multiplexing, multi-function integration, etc., the complexity of the solution increases.
Vicor also says that when it comes to power design, less is more. The potential for higher assembly defects in discrete designs increases exponentially, making both design and manufacturing inefficient.
I pulled up a 2015 article written by TI that mentioned that power modules provide a proven, specified solution, while discrete power supplies allow for more customization of the application. Both are effective solutions with various trade-offs for space-constrained applications.
By their very nature, power modules employ smaller inductors with higher DC resistance (DCR) to minimize their overall size. Typically, discrete power supplies use larger inductors (which have a lower DCR) to maximize efficiency. There is a clear trade-off between scale and efficiency.
In addition, in terms of cost, TI also gave specific consideration criteria. All other projects being equal, power modules cost more than discrete power ICs due to the integrated inductor and its components and assembly costs. However, the cost of a complete power supply exceeds the cost of a power IC. Other expenses include the cost of picking each individual component during assembly and placing it on the PCB, the cost of qualifying, ordering, and stocking each item in the BOM, the cost and risk of PCB layout (as the wiring of inductors and switch nodes requires careful consideration and adds some risk), ;P the cost of the CB itself – the larger the PCB, the more expensive it is. Power modules are more expensive, but they save PCB space and simplify design efforts.
The figure shows the data for 2015, comparing the cost and performance of modules and discrete components.
In addition, in addition to low-power power supplies, high-power power modules are also growing rapidly. For example, various SiC and IGBT modules have been fully used, including IPM, and modules and discrete devices are used in high-volume production vehicles. Example - The drive units in Tesla Model S and Model III both use discrete packages. I can only speculate here, but I guess it's a cost and supply chain driven decision. Manufacturing discrete semiconductors is inherently cheaper (fewer components and manufacturing processes), and they can be produced at a much higher rate than power modules.
Overall, the use of power modules is an easier and more convenient way to develop medium and high power converters/inverters. But if you need to consider more variables, such as heat dissipation interface, stray inductance, current balance, etc.
Wireless engineers are also discussing modularity
When designing IoT devices, the decision between using a wireless module or a system-on-chip (SoC) is also a critical and challenging one. Each option has its own unique advantages and disadvantages, and choosing the right technology requires a balance of performance, features, and cost.
A wireless module is a pre-certified unit that serves as a complete wireless solution and typically contains a radio transceiver with a microcontroller, software stack, and antenna. Wireless modules are favored for their ease of use and reduced development time.
A system-on-chip (SoC) is an integrated circuit that combines a microcontroller unit and a radio frequency (RF) front end on the same silicon die. SoCs offer more control and flexibility, but require more design work.
We'll compare the cost of wireless modules and SoCs using the following metrics: initial purchase cost, development cost, supply chain cost, and scalability cost.
Initial purchase and development costs
Wireless modules include pre-certified RF circuitry, antennas, and software stacks, all of which add to the cost of purchase. In contrast, an SoC is simply an integrated circuit with no additional components. Since they lack add-ons in the wireless module, the initial purchase cost is lower. This makes SoCs attractive to designers on a budget.
However, the same simplicity means that development costs can rise quickly. Consider the following list of development-related expenses: RF design and engineering expenses, laboratory equipment and infrastructure investments, costs of PCB configuration and antenna selection, and certification fees.
Wireless modules include pre-engineered, pre-tested RF circuitry, eliminating the need for in-house RF design expertise and reducing the need for lab testing. They are also often pre-certified and include built-in antennas and pinouts, simplifying the PCB layout process. These things are all included in the initial purchase cost and don't require more spending during the development phase.
SoC-based designs, on the other hand, require additional expense and time to design, test, and certify before entering the market. Wireless module-based designs have a shorter time-to-market and a faster return on investment.
Supply chain and scalability costs
It's easier to source modules than all the individual parts required for an SoC-based design, but the latter option can lead to higher supply risk, especially for smaller companies or during parts shortages. However, relying on module suppliers to ensure continuity of supply can be costly. If an SoC is chosen, a larger company or high-volume production may benefit from more control over the supply chain.
In addition, wireless modules often mean a higher unit cost, which is a disadvantage when scaling up. For mass production, the lower unit cost of the SoC can offset the higher development costs.
Silicon Labs analyzes the cost of using wireless modules and SoCs in IoT designs. They compared the cost of BGM210P wireless Bluetooth modules and EFR32BG21 Bluetooth SoCs, both of which are sold in bulk at 300,000 pieces.
Their cost comparisons are based on the following assumptions:
Purchases range from 10,000 to 300,000 units, and the wireless module and SoC are priced at $2.99 and $1.11, respectively.
The SoC's BoM totals $0.55 and needs to be combined with testing during the manufacturing process, where $0.05 costs for testing and $0.50 for other BoMs.
Overall, using a wireless module costs $1.33 more than using an SoC.
Due to the complex design, certification, and regulatory approval process for wireless products, adopting an SoC requires an additional six months of development time. Based on an average engineer salary of $100,000 per year, let's assume that this would cost around $50,000 extra.
With these factors in mind, and taking into account the time-to-market and the additional overhead that comes with using SoCs, the balanced production of wireless modules and SoCs is between 500,000 and 1,300,000 units. If you ignore the loss of revenue due to time-to-market delays, the break-even point drops to between 100,000 and 200,000 units.
When the production volume is less than 500,000 pieces, it is more profitable to use a wireless module than an SoC. This is due to the higher upfront costs associated with SoCs and the longer time to market. However, once production reaches the break-even zone, these upfront costs may be spread over enough units to make the SoC a more profitable option.
As a result, SoCs may not be the best choice for all high-volume products. Despite the potential cost-effectiveness of SoCs at scale, there are also risks that cannot be quantified, such as technical issues or certification issues.
Designing with SoCs gives product developers the flexibility to custom design their systems and integrate the hardware and software features they need. The flip side of this customizability is increased complexity and longer development time – designers need to have a deep understanding of the SoC architecture and the software running on it.
In contrast, prefabricated wireless modules typically require less development time and expertise, but can fall short in terms of customization and integration. Wireless modules may be more cost-effective for smaller production runs, or if fast time-to-market is critical, and for larger volumes, or if in-house expertise is available, SoCs may be more cost-effective.
Older embedded core boards
SoM is also a popular modular product. SoMs integrate the core components of an embedded processing system, such as processors, memory, and peripherals, on a single board.
However, unlike SoCs, SoMs provide this functionality on a PCB or module rather than a single chip. In this regard, the SoM is a board-level system. Usually, it is a small board in which many ICs or chips are integrated.
The use of SoCs really makes things simpler because designers don't have to put effort into various aspects of the circuit, and there are a lot of features packed into the chip.
However, designers still need to have a detailed understanding of the SoC chip, including the capabilities of each pin, the thermal performance of the SoC, and the pad design.
To solve this problem, the SoM offers a very small module that can be connected to a substrate, simplifying the entire process while keeping the power budget low and making it suitable for a variety of applications.
During mass production, delays in manufacturing and testing make time constraints even tighter. SoMs make the entire design process much smoother. All an engineer needs to do is select the SoM that fits your requirements, integrate it with the master, and you're good to go.
Developers can use all the time saved to focus on their application software, significantly reducing time-to-market and overall costs.
Although the SoM may look similar to an evaluation board like the Arduino, it is much more than that, and the SoM can also be used in the final product without loss of reliability or performance.
No in-depth knowledge and experience of hardware is required, making it ideal for software developers. Some SOMs also come with drivers, so developers can focus entirely on the application layer.
Make the design process faster, more efficient, and more resource-efficient for hardware developers. FPGA performance and flexibility can be achieved without going through the slow and cumbersome PCB design and manufacturing process. It has a high degree of high performance, reliability and scalability.
It is highly interchangeable and easy to upgrade. Upgraded versions of SoMs with the same form factor can easily replace older cells without having to completely change the underlying hardware, simplifying the lifecycle of the product.
summary
What is the best option? For engineering problems, it is always necessary to analyze the specific problem, and this is an unstable answer that depends on many factors: the specific product, the designer, the urgency of the product release, the production volume, and so on. However, in the future, with the progress of modular products in more aspects, it is believed that they will be more and more accessible to a wider range of groups.