It is a rare occurrence that a single invention is so significant that it can directly or indirectly change almost every facet of life. Arguably, the last such occurrence was when William Shockley, John Bardeen, and Walter Brattain of Bell Laboratories invented the transistor in 1947. This single device has enabled the proliferation of PCBs and electronics that are today a part of virtually all the devices, systems, and equipment that we use at home, work, and everywhere else. Although there have been many variants and improvements to the original design, the basic functionality still remains the same; that is, to control when (and how) an input signal is allowed to connect to an output circuit or switching.
Switching is utilized in the vast majority of electronic circuits and is absolutely essential for power supplies. Linear power supplies typically use diodes, which are also switches; however, switching power supplies or switch-mode power supplies (SMPSs) usually employ transistors as more precise and efficient output control is required. Let’s take a look at SMPSs; including their uses and applications and then establish a set of tips to ensure that the best manufacturing for your switching power supply design.
Applications and Uses of Switch-Mode Power Supplies
In general, the SMPS, in contrast to the linear power supply, is more flexible, precise, and efficient. This power supply model typically utilizes pulse width modulation (PWM) to control the switching times (ON and OFF) of transistors, thereby accurately generating output signals. SMPSs are used in an extensive range of applications. The areas where they are most utilized are: digital products like computers and mobile device chargers; automotive chargers; medical test equipment; audio equipment; arc welders; telecommunications devices; and other systems. SMPSs may be one of several different types. Common types are:
SWITCHING POWER SUPPLY DESIGN TYPES
|Conversion||Output Voltage |
|Energy Storage Element|
0 - 1k
0 - 5k
|DC/DC||Vout ≤ 0||Inductor|
0 - 150
100 - 200
0 - 250
100 - 1k
0 - 2k
400 - 5k
* Power ranges are approximations and are not meant to reference any specific SMPS unit.
In addition to flexibility, SMPSs are very efficient with rates higher than 90%. These positive attributes come at a cost, however, as the use of devices, such as transistors for switching, creates high-frequency noise. Now, let’s discuss how to mitigate this drawback and ensure that the switching power supply design also facilitates the best PCB manufacturing.
Requirements for Good Switch-Mode Power Supply Design
When designing SMPSs, especially for use in digital equipment, the control circuitry may be complex and contained in a small switcher IC package. In this case, the primary design concerns are ensuring the proper input range is used and that the power supply filter design is adequate for the intended load(s). At other times, it may be necessary to design the switching circuitry directly, as well. Irrespective of your situation, following the set of tips below, as applicable, will ensure that your design is not only buildable but also aids your contract manufacturer (CM) in optimizing the efficiency of your PCB manufacturing process.
Ensuring Efficient Switching Power Supply Design Manufacturing
|TIPS TO ENSURE EFFICIENT SWITCH-MODE POWER SUPPLY MANUFACTURING|
|Tip #1||Minimize component footprints. |
It is generally desirable for your SMPS to occupy the smallest amount of space possible, especially when used in a digital system. These means minimizing spacing and clearances between footprints.
|Tip #2||Minimize trace route lengths.|
Limiting trace lengths helps to keep your design compact, but also minimizes losses and improves signal integrity.
|Tip #3||Ensure copper weights are adequate.|
As your SMPS may operate over a range of voltages and powers, it is imperative that your traces can carry the currents for any case within those ranges.
|Tip #4||Perform thermal analysis for manufacturing.|
Design your board for good heat distribution to facilitate good solder joint quality, while making sure that temperature coefficients of materials are much higher than the temperatures your boards will be exposed to during assembly.
|Tip #5||Ensure your selections fall within CM DFM tolerances.|
All of your board specifications must comply with your CM’s DFM rules and guidelines. You can ensure this by making good use of DFM checks.
|Tempo‘s Custom PCB Manufacturing Service|
Following the tips listed above will help your CM produce your boards efficiently and aid your entire PCB development process. Tempo Automation is the industry’s leader in fast, high-quality PCB prototyping and low volume production. We incorporate a white-box approach to manufacturing to create a synergistic relationship with you for accurate incorporation of your design intent and optimal synchronization between your board specifications and our equipment, processes, and capabilities.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on ensuring the best build of your switching power supply design, contact us.