Why do small Transformers like PCB mounted transformer, planar transformers, and SMD transformers heat up? What causes the overheat?
It’s a physical phenomenon for small transformers—like PCB, planar, or SMD transformers—to heat up. It indicates that the transformer is performing its energy conversion function. The heat mainly comes from power losses, where the dissipated energy is converted into thermal energy.
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Heat Generation Mechanisms of Transformers
Copper Loss (I²R Loss)
What it is:
When current flows through the winding (copper wire), some electrical energy is lost due to copper wire resistances.
Why it happens:
The current is high or the wire is very thin. Since small transformers use thinner wires due to space limits, their resistance is higher, which makes them heat up more easily.
Core Loss (Magnetic Loss)
What it is:
Energy loss occurring in the magnetic core when it is subjected to an alternating magnetic field.
Why it happens:
Eddy current losses and hysteresis losses within the core material. In high-frequency switching power supplies, for example DC-DC convertor, eddy current losses can be especially significant.
Design and Process Factors
Excessive Power Density
When a lot of power is packed into a small space, there isn’t much area for heat dissipation, so the temperature goes up.
PCB Layout Design
Insufficient copper pour area, poor grounding, or improper inter-winding coupling design can increase localized losses and result in additional heat generation.
How to Reduce Small Transformer Heat Generation?
Even though it’s normal for transformers to generate heat, too much heat can shorten their lifespan. Here are a few ways to keep temperatures under control:
- Improve PCB Copper Areas: Make sure there’s enough copper around the transformer pins for grounding and heat dissipation, which helps spread the heat.
- Choose the Right Core: For high-frequency designs, use low-loss cores like ferrite, or consider air-core toroidal transformers.
- Limit Power Density: Avoid pushing too much power through a very small transformer.
- Add Extra Cooling if Needed: For higher-power small transformers, heat sinks or cooling fans can help remove excess heat.
As a professional manufacturer, we, Partopia Transformer, have over 30 years of experience in the design and production of small transformers. We understand the common causes of heating and know how to avoid potential problems through proper design, material selection, and manufacturing processes. You can trust us to provide a high-quality transformer that is well suited to your application and performs reliably over the long term.
