April 9, 2020 by Bruce Rose - 7 Minute Read
As everyone is aware, we are in a different world with the presence of COVID-19 and the associated issues. Fortunately, we are regularly hearing news regarding companies and individuals working to provide near term solutions to many of the problems we are encountering. The shortage of medical equipment has taken center stage and many companies are looking to quickly manufacture equipment to address these shortages. As a supplier of electronic power supplies, we are frequently being asked “Where can we buy power supplies for medical equipment?”
Unfortunately, it is our view that the power supplies and other components to build electronic medical equipment will be in high demand and short supply for the near future. This blog will review why the components are not immediately available and also discuss activities that may serve as a partial solution to the shortage issues.
Perhaps the biggest reason that electronic components are not available to ramp up production of tens of thousands of units within weeks is due to the efficient business model that has been steadily developing over the past decades. The electronics industry is only one of many market segments that have adopted the build to order (BTO) and just in time (JIT) business models to improve efficiency. These techniques work well when companies have the ability to create long term forecasts and thus predict market needs beyond just the near future. Unfortunately, BTO and JIT techniques do not serve well when there is a near term disruption in business plans.
The BTO and JIT models extend through manufacturers of electronic components to the suppliers of these manufacturers. In an efficient system all of the suppliers in the chain are operating at or close to capacity and producing products that have forecasted requirements in place. Addressing near term and unexpected increased demands often requires reallocating existing work in progress (WIP) from the previously forecasted demand to the new un-forecasted demand. In the case of medically certified components, the WIP would be re-allocated from one medical application to another medical application and thus possibly not improving the disruption causing the increased demand.
Among other functions, electronic component distributors serve as a buffer for variances in BTO and JIT but the distributors have developed models to stock only the amount of inventory that is typically required by their customers. Purchase requests due to large surges in demand, as present with the COVID-19 event, exceed the inventory holdings of the distributors and they must then place orders in the BTO and JIT queues of their suppliers.
During this COVID-19 event there is the desire to quickly increase the production quantity of existing medical product designs. In the existing designs the internal components have already been selected and thus the option is to either acquire more of the specified components or to find acceptable substitute parts (known as “crosses”). The challenge in selecting acceptable substitute parts is that they must be equivalent in form, fit, and function.
Some power supplies may serve as appropriate crosses to those from other manufactures, but the requirements of the power supply function need to be carefully specified and evaluated by the customer. The original power supply data sheet should be reviewed to determine which specifications are required and which specifications are not important and then to ensure that the required specifications are met. Typically the complete list of specifications between any two power supplies will not be identical. Due to the differences in specifications it will be difficult for the new vendor to confirm that their supply will work in the application without significant cooperation from a customer engineer who is familiar with the application.
Medical grade electronic power supplies require regulatory testing and approval before they can be sold. Designing or modifying a power supply or opening a new manufacturing facility are all activities that may initiate the requirements for regulatory testing and approval activities and these activities often take multiple weeks to be completed. In addition to testing of the components, the final medical product will also be required to undergo regulatory testing and approval processes.
This article from All About Circuits provides additional insight and information regarding the design and manufacturing of ventilators at this time. Of note in the article are references to changes in US and UK regulatory agency policies regarding the certification of ventilators to address the COVID-19 crisis. Section IV of the document from the US Food and Drug administration addresses relaxing of the policies for modifications to FDA-cleared devices.
Knowing that quickly acquiring high volumes of components can be an issue (due to unforeseen circumstances like a pandemic), there are design decisions one can make to minimize these challenges. A high level design philosophy would be to design the product to consist of independent modules rather than a tightly integrated platform. Some examples of possibly independent modules include the power supply and the display. While the modules will need to be functionally equivalent and may need to be form and fit equivalent, the components within the modules will not need to be form, fit, and functionally equivalent. The following are examples of power module architectures incorporating different internal components but all achieving the system requirements:
Including wall mount or desktop external power supplies within a module can also be an option for ac-dc supplies. The ability to acquire sufficient components to build lower volumes of many equivalent modules could enable high volume production of the final product by using many versions of the low volume modules. It is recognized that the cost, size, and performance of the system may be compromised by a modular design. However, high volumes of a sub-optimal design may serve better than low volumes of an optimized design, if the parts to build the optimized design in high volumes cannot be obtained in the required time.
Almost all external or chassis mount power supplies will have input and output connectors. Selecting industry standard connectors will help to enable locating sufficient inventory of suitable components from multiple manufacturers. Power supply and connector vendors can help to select appropriate industry standard connectors if the product design team is not familiar with them.
Specifying standard and common power supply voltages will help to increase the probability of available power supplies. Hopefully most engineers would recognize that 7.8 Vdc is neither a standard nor common supply voltage. However, it should also be recognized that although a section of the product load may require 9 Vdc and it may be a standard voltage that it is not as common as is 12 Vdc. Specifying a power supply module to provide 12 Vdc and then using either a discrete, integrated, or modular linear or switching regulator to produce 9 Vdc for the section of the load requiring that voltage may make the components for the design easier to acquire.
Although CUI, along with most other electric component vendors, would like to be able to deliver tens of thousands of any part requested by a customer within a few days or weeks, that is not a realistic expectation. The most efficient process to rapidly deliver large volumes of a product to the market is for the design teams to work with vendors early and through-out the design process to adopt achievable options.
We here at CUI Inc applaud all of the individuals throughout the world who are personally contributing to the fight against COVID-19 and the associated issues. It is the hope and desire of the employees at CUI that we all work together in this troubled time to address the challenges facing us so that we get through this period with the least amount of suffering and are able to resume a more normal lifestyle in the near future.
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