Everything You Need to Know About The Motherboard Voltage Regulator Circuit

Meeting The Components

The main components of a voltage regulator circuit are the already mentioned chokes (which can be manufactured using two materials, iron or ferrite), transistors and electrolytic capacitors (good motherboards will provide solid capacitors, which are better). The transistors used on the voltage regulator circuit are manufactured under a technology called MOSFET (Metal-Oxide Semiconductor Field Effect Transistor) and many people call them simply “MOSFET” (some motherboards, in particular the ones from MSI based on "DrMOS" technology, use integrated circuits instead of transistors). Some motherboards come with a passive heatsink on top of these transistors to cool them down, which is a desirable feature. There are other very important components present on this circuit, especially integrated circuits. You will always find an integrated circuit called “PWM controller” and in good designs a tiny one called “MOSFET driver.” We will explain what they do later.

Motherboard Voltage RegulatorFigure 2: A close-up on the main voltage regulator circuit.

Motherboard Voltage RegulatorFigure 3: Motherboard with passive heatsink on top of the transistors.

Now let’s talk a little bit more about each component.

As mentioned, you can find two kinds of chokes on the voltage regulator circuit: iron or ferrite. Ferrite chokes are better as they provide a lower power loss compared to iron chokes (25% lower, according to Gigabyte), a lower electromagnetic interference (EMI) and have a better resistance to rust. It is easy to tell them apart: iron chokes are usually “opened” and you can see a thick copper wire inside, while ferrite chokes are “closed” and usually have a marking starting with the letter “R” on top. On Figures 4 and 5 we show you the difference between them. There is one exception, though. There are ferrite chokes that are big, rounded and opened, shown in Figure 6. It is very easy to identify this kind of ferrite choke, as it is rounded instead of squared.

The voltage regulator circuit will have one choke per “phase” or “channel.” Don’t worry about this now as we will explain what this is in detail later.

Iron ChokeFigure 4: Iron choke.

Ferrite ChokeFigure 5: Ferrite choke.

Ferrite ChokeFigure 6: Ferrite Choke.

Author: Gabriel Torres

Gabriel Torres is a Brazilian best-selling ICT expert, with 24 books published. He started his online career in 1996, when he launched Clube do Hardware, which is one of the oldest and largest websites about technology in Brazil. He created Hardware Secrets in 1999 to expand his knowledge outside his home country.

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