PCB transformer - A Complete Guide

PCB transformer – a complete guide

Feeling tense about AC-DC electronic applications?

PCB transformer is a dependable solution to handle power, voltage, and current ratings without compromising the device’s quality. 

Do you have enough idea about PCB mount transformers, their working procedures, or mounting? This article will be a superb resource for you to get a clear concept of all these subjects. 

Let’s make a move.

Table of Contents

What is a PCB transformer?

PCB transformer is a specific kind of electrical component mounted on a PCB to transform energy from circuit to circuit through magnetic induction. The matter of fact is that this PCB-mount transformer transforms power by changing the current rating of coils without making any mechanical joints.

PCB Transformers

In terms of voltage switching, it has two types. They are-
Step Down: Primary voltage>Secondary voltage
Step Up: Primary Voltage<Secondary Voltage

Why are transformers used in PCB?

PCB transformers have extensive use in PCB-based electronic applications because of their outstanding facilities. The most important benefits of these types of equipment include-

  • Establishing necessary isolation between the power grid and a device.
  • Amplifying the wave inputs
  • Varying voltage and current ratings without disturbing the overall power. This property helps reduce power loss.
  • Switching the electricity to the desired potential and ampere for a particular application.

How do PCB transformers work?

A PCB transformer consists of three principal parts.

  • Primary coil
  • Auxiliary/secondary coil
  • Core

A transformer mainly alters the output current and potentials from lower to higher or vice versa as per requirement. But how?

PCB Transformer's Composition

Let’s find out.

  • In the beginning, the core receives a magnetic flow when the electricity goes through the primary coil.
  • Then, the magnetic flow moves to the auxiliary coil via the core.
  • In the end, an alternating current is induced to the secondary coil through the magnetic flow.
  • Remember, the overall power remains unchanged during this process.
    You can look at the following equation to get an idea about the current and voltage ratings in both coils-


Voltage rating at primary coil

Types of PCB transformers

Let’s look at some prominent PCB transformer types at a glance-

Power transformer (with laminated core)

This is one of the most widely-used PCB transformers in power electronics. These transformers specialize in reducing the original potential to match the power. The power range of power transformers covers from mW to MW; that is a huge range, isn’t it?
Special features

  • Reduced Eddy current loss due to core lamination
  • Integrated thermal cut-out to shut down power supply during overheating
  • Built-in split bobbin that ensures necessary insulation between the transformer windings
  • Facility of installing a screen winding or shield between the primary and secondary coils to avoid EMI (Electromagnetic Radiation).

Flyback transformers (FBT)

FBTs are very common in CRT (Cathode Ray Tube) and plasma balls because of their compatibility with high-frequency and high-voltage circuits. With their capability of delivering high Anode DC voltage, Flyback transformers are widely used in CRTs.

Flyback PCB Mount Transformer

Usually, FBT controls the picture quality of CRTs in most cases. Besides, FBTs are integrated with a voltage multiplier. That’s why you can find the FBT outputs are pulsed frequently.

Auto transformer

Made up of one winding, the Autotransformer is a cheaper and lighter PCB mount transformer than other transformers having two windings. Moreover, its efficiency is also higher than others.
Special features

  • Its equivalent power rating is lower than the actual power load
  • It can connect high voltage level networks in power distribution systems.

Balun transformers

Balun transformers take care of impedance matching during their operation.

Audio transformer

If you intend to handle audio signals in c circuits, an audio transformer is a must.
Special features

  • It can merge or split audio signals as per requirements
  • It creates a blockage for DC components and RF interface in audio signals
  • Ensures impedance matching in high-frequency and high-speed electronic applications
  • Makes a bridge between 2-wire and 4-wire communication networks.

Current transformer

CTs (Current Transformers) have extensive use in relays and metering devices. These are usually measuring equipment that is connected in a series connection in a circuit. CTs provide an auxiliary current that is directly proportional to the primary current.

Here you can find an insulated toroidal core that is wrapped with certain wire turns. Besides, an uninsulated bus bar or insulated cable passes through that core.

Grounding transformers

  • Usually made up of one winding
  • A 3-wire polyphase system
  • It supplies adapt phase to neutral loads
  • It creates a return path for current to a neutral
  • Combined with a zigzag winding
  • Allow inclusion of an isolated wye-delta connection

Phase shifting transformers

If you have a problem with excessive power flow in a shorter channel? Phase shifting transformer drives the surplus power to a longer channel by changing the phase.

Being a customized PCB mount transformer, a phase shifting transformer alters the phase between input and output. As phase shifting helps manage power flow in electrical grid systems, this transformer is very common in power electronics.

Potential transformer

Its other name is voltage transformer. Usually, PT (Potential Transformer) connects in parallel. Its main uses are in protective relays, phase shift isolation, and high-voltage circuit metering.

Pulse transformer

This PCB transformer transmits rectangular electric pulses. A pulse transformer is widely used in telecommunication systems and digital logic-based applications.

How do you identify a PCB transformer?

You can easily identify a PCB transformer by measuring its resistance, turn ratio, or voltage ratings. In a step-up PCB mount transformer, the primary resistance and number of turns increase at the secondary coil. The scenario becomes the opposite in the case of step-down transformers. So, you can measure the resistance through a multimeter or ohmmeter and find out the nature of the PCB transformer you are using on your circuit board.

How to mount a transformer on circuit boards?

When you want to mount a transformer on circuit boards, you must consider some specifications to overcome the challenges.

Usually, PCB transformers don’t come with a cooling mechanism. The Planer transformer is an exception in this case, which has an integrated heat sink. But, manufacturers set the power ratings in such a way that the operating temperatures remain below the threshold value.

Transformer Mounting on a PCB

The importance of inductance in high-power PCB applications is-

  • Setting of the coupling strength to the auxiliary components in AC-DC conversions.
  • Switching of DC-DC conversion in Flyback and LLC resonant converters.

Form factor
You must place a PCB transformer according to its form factor. Otherwise, it will be vulnerable to vibration and mechanical stresses.

Mounting process is a pivotal point for PCB mount transformers. You need to decide concerning your application, budget, etc.

Usually, THT (Through-hole Technology) comes with longer pins so that the transformers can withstand vibration or other stresses. In contrast, SMT (Surface Mount Technology) offers flat surfaces at affordable costs.

Primary/secondary current and voltage ratings
These values indicate the maximum safe value of current and potentials for both coils of a transformer.

Power rating
This is a DC property that indicates the resistive power that a PCB transformer can handle. That’s why check the ratings on the datasheet before mounting a transformer.

Besides, you must check the size and Z-axis span while mounting a transformer on a circuit board.

How do I choose a PCB transformer?

How do I choose a PCB transformer

To choose a proper PCB transformer for your electric circuit board, you must keep the following things in mind-
●Transformer size
●Where do you use the transformer?
●Form factor
●Input/Output power ratings
●Operating temperature
●Cooling system
●Inductance rating
●Shelf life
●UL-94 ratings for materials
●Voltage/Ampere ratings
●Suitable mounting style

PCB transformer is a specific kind of electrical component mounted on a PCB to transform energy from circuit to circuit through magnetic induction.

  • Power transformer (with laminated core)
  • Flyback transformers (FBT)
  • Auto transformer
  • Balun transformers
  • Audio transformer
  • Current transformer
  • Grounding transformers
  • Phase shifting transformers
  • Potential transformer
  • Pulse transformer
  • Cooling
  • Inductance
  • SMT or THT
  • Primary/secondary current and voltage ratings
  • Power rating


This is everything you need to know about PCB transformer in the present times. As technology is growing day by day, its applications are also increasing simultaneously. That’s why you must be aware of the ins and outs of PCB mount transformers.

IBE is a reliable PCBA manufacturer of PCB mount transformers at affordable costs. Contact us immediately to get your quote and upgrade your device.

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