How to choose the DC power supply?

When selecting a DC stabilized power supply, there are two main points to consider: output range and circuit method.

Output range
The output range of a DC regulated power supply differs greatly depending on whether it is a single-range or wide-range system.

A single-range power supply is a power supply in which the combination of voltage and current that can be output is determined by the rated voltage and rated current. For a stabilized DC power supply with a rated voltage of 80V and a rated current of 10A, the maximum output voltage is 80V, the maximum output current is 10A, and the maximum power consumption is 800W.

On the other hand, a wide-range (variable-range) power supply is one in which the combination of voltage and current that can be output is determined by the power consumption in addition to the rated voltage and current.

In the case of a regulated power supply with a rated voltage of 80V, a rated current of 50A, and a power consumption of 800W, the current that can be output at the maximum output voltage of 80V is limited to 10A, which is less than 800W of power consumption. Similarly, the voltage that can be output at the maximum output current of 50A is limited to 16V, and it is not possible to use a combination of maximum output voltage and maximum output current as in the single-range system.

Output Range – Comparison between single and wide

If you are choosing the same power consumption, single-range power supplies are less expensive. If you always perform tests with a fixed current and voltage, it is better to choose a single-range power supply.

However, when checking electronic devices that require a large current only at start-up, such as motors or electronic devices powered by batteries whose output voltage drops as they run down, various combinations of voltage and current are required. Therefore, if you try to use a single-range power supply, you will need a lot of power supply units.

Also, if you prepare a single-range power supply that covers such a wide range, the cost will increase, and the size of the power supply will also increase. In such cases, a wide-range power supply can be chosen to save both cost and space. There are two types of wide-range power supplies: those with a wide output range and those with a narrow output range. The model shown in the example above is capable of 5 times wider range output. When choosing a power supply with wide-range power, be sure to check the range width.

method, series regulator method, linear regulator method, series dropper method, etc. The input Alternating Current (AC) is converted to Direct Current (DC), and then the voltage and current are controlled by a transformer and sent out. The switching method, on the other hand, converts the current converted to DC into high-frequency AC power using coils or semiconductors and then converts it back to DC to control the voltage and current.
In the past, single-range DC power supplies were the mainstream. In recent years, however, the demand for wide-range (variable-range) DC power supplies has been growing as more devices run on batteries, and more types of electronic devices are used.

AC to DC conversion methods
There are two types of circuits for DC regulated power supplies: dropper and switching.

The dropper method is also called the series method, linear method, series regulator method, linear regulator method, series dropper method, etc. The input Alternating Current (AC) is converted to Direct Current (DC), and then the voltage and current are controlled by a transformer and sent out. The switching method, on the other hand, converts the current converted to DC into high-frequency AC power using coils or semiconductors and then converts it back to DC to control the voltage and current.

The disadvantage of a switching type DC regulated power supply is that its mechanism generates minute noise. Therefore, it is not suitable for equipment that is easily affected by noise. On the other hand, the dropper method has the advantage of low noise and high responsiveness to changes in load. However, they also have the disadvantage of being large and heavy and generating a lot of heat.

Ordinary desktop computers also have a built-in switching DC power supply, but if you want to use a dropper system, you need a power supply as big as a toaster. For this reason, switching DC power supplies have become the norm in recent years.

When selecting a DC power supply, first determine the output range by checking the voltage and current required for operation, then check the effects of noise, responsiveness, and the operability of the equipment, and choose the best one for your application.