High Voltage Switching Regulator Layout Guidelines You Should Follow

March 25, 2020 , in Blog, Industrial

They say that you can point out the new employees because they are still trying to figure out how to get to the bathroom. This may be true; however, it is a safe bet that wherever the bathroom is located, it is strategically placed. In fact, most buildings have a well-thought-out floor plan. In industrial facilities, the layout is even more important, as the relative location of machines, equipment control, and inventory can impact production efficiency and other operations. Understanding the importance of this may not help anyone learn the best path to the restroom any faster, but it will at least help with appreciating why it is where it is.

PLC motor controller

Industrial equipment control

Just as placement is important for the best industrial production, PCB layout is probably the most important single factor for a good circuit board design. Your board layout not only specifies the materials and components but also how the traces will be run on and through its construction. When your design contains high voltage components or accepts, processes and/or distributes high voltages, and/or currents; as is done by a switching power supply or regulator, there are special considerations that must be incorporated into your design and manufacturing processes. In order to best understand these high voltage switching regulator layout guidelines, it is advisable to first explore the use of these boards in industrial environments.

Industrial Use of High Voltage Switching Regulators

One of the important electronic devices found in industrial power distribution systems is PCB power supply. There are two types of power supply, which is often used interchangeably with the regulator, as the function is to provide a regulated output for the load(s) circuits, linear, and switch-mode or SMPS. Linear regulators, which are primarily used in industrial equipment, tend to be rather large and less efficient in comparison to switching regulators. They also tend to be less noisy, which is an attractive attribute in high voltage (HV) industrial systems where achieving electromagnetic compatibility with nearby systems is or should be a major objective, and rather simple to design. Switching regulators, on the other hand, are a bit more complex.

Switching regulators provide a wide range of flexibility for converting an input supply power into a stable output or outputs. This includes the following specific design and functionality types.

Types of Switching Regulators

  • Buck (step-down)
  • Boost (step-up)
  • Buck-Boost (step-down or step-up)
  • Push-Pull
  • Flyback
  • Forward
  • Half-Bridge SMPS
  • Full-Bridge SMPS
  • Single-Ended Primary-Inductor Converter (SEPIC)
  • Cuk (two inductor inverting converter)

All of the regulator types listed above accept a range of DC input voltages and generate a fixed DC output voltage. The output voltage remains constant regardless of load changes. This is accomplished by providing a control signal (usually PWM or hysteretic) that varies the duty cycle or ON operation time for the device. For PWM, the regulator input signal is applied to a PWM controller or switch that varies the duty cycle, while for hysteretic control, which is the fastest switching, the output is fed back and compared with a reference voltage. If the regulator output is too high, it is switched OFF. If it’s too low, it is switched ON.

Switching regulators are typically used in digital circuits; however, they are also used as high current drivers in industrial applications. They have the advantage of much better efficiency with respect to linear regulators. However, they are noisier. Mitigating noise and frequency variation, along with supplying the regulator control are major factors that affect the design and necessitate that high voltage regulator layout guidelines are followed.

Optimizing Your HV Switching Regulator Layout Guidelines

HV switching regulators for PCBAs may come in IC packages or it may be necessary or preferable to use a custom design. Even if ICs are used, it will be necessary to design the layout for external circuitry on the board. And to ensure the best regulation or most stable operation with minimal EMI, the following guidelines should be followed.

The HV Switching Regulator Layout Guidelines You Should Follow

  • Components
      • Inductors

Use low EMI rated inductors and maintain good creepage and clearance distances from other components.

      • Capacitors

For capacitors, It is best to use SMDs and a good routing scheme as opposed to through-hole. This includes locating caps as close to the source as possible (i.e. IC pin). Again, clearances are important to minimize the effects of parasitics.

  • Traces
      • Feedback

Regulators rely heavily on feedback for proper operation; however, they can be subject to EMI if not located away from noise sources such as inductors. Therefore, it is advisable to route the feedback traces as far away as possible from these devices, even on the opposite side of the board. Do this in conjunction with increased trace width to improve signal integrity.

      • Vias

For high currents between layers, it is good practice to use one standard via for every 200mA of current transfer.

      • Current Loops

It is also a good idea to have current loops flowing in one direction for the ON state and the other direction for the OFF state.

  • Planes
      • Grounding

Anytime you have a multilayer PCB design, grounding is important. For switching regulators, the grounds for switches, capacitors, and IC should be close together. Make power traces as short, direct, and thick as possible.

  • Thermal management
      • Heat dissipation

If possible, utilize board areas as a heat sink to move heat away from devices, especially high power ICs. Thermal vias should also be utilized to assist with heat dissipation. However, care should be taken to ensure this integrates well into the overall thermal dissipation and distribution strategy.

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  • Standard quality testing; including X-ray and inline AOI.
  • Advanced QC testing; including flying probe, time domain reflectometry and ROSE.

Following the guidelines above should help ensure that your HV switching regulator performs to your expectations and is manufacturable. To have your board built to the highest quality standards and with the fastest turnaround, we at Tempo Automation will work with you to transparently integrate your design intent with the best PCBA manufacturing process.

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 switching regulator layout guidelines for your industrial PCBA, contact us.

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