A Deep Look Into Power Supplies

A Deep Look Into Power Supplies

For those of you who know nothing about PSUs, today it’s being taken from the top. The abbreviation PSU stands for power supply unit. Regrettably, this is something many builders ignore. Instead of choosing an adequate PSU for their systems, users typically acquire all of the other components first, using leftover funds for the power supply purchase.


You can think of the PSU as the heart of a PC; it is the most significant part of the system since it feeds power to the other components, including the CPU, graphics card, hard drive, SSD and so on.

If the PSU fails, it affects all of the other pieces. And in some cases, a malfunction of the PSU can damage other components as well, specially if the PSU is of low quality with inefficient protection characteristics. The whole concept is very simple: when a current passes through an inductor, a magnetic field is created around the wire.

Every change in current affects the magnetic field, which in turn induces voltage across the inductor. That voltage produces a current flow opposite of the initial current. Inductors are used in many electronics and they play an specially important role in PSUs.

In PSUs, the best electrolytic capacitors are considered those rated at 105 degrees Celsius, since they have increased life span compared with ones rated at 85 °C. Of course, the capacitor manufacturer plays a key role, with Japanese-made capacitors always being the preferred choice.

In many cases, capacitance might be within specifications but the ESR is way off, resulting in poor functionality. Also, increased ESR greatly affects the operational temperature of a cap leading to its fast degradation and a much shorter life span.


The SMPS/PSU, in order to offer useful information to all, even those who might not have an electronics background. Even though we covered all major areas, admittedly it’s far too difficult, if not impossible, to simplify such complex concepts in a single article, specially when referring to electronics design.