Components Expert

DC voltage converter-how to choose the right converter?

Every electronic device needs a suitable power source. In most cases, we just plug the plug into the socket. However, it is worth noting that very few devices are powered by a variable voltage of 230V (available from an outlet), and more commonly, the required constant voltage is much lower. In order to provide this voltage, the manufacturer designs a suitable, usually very extensive power supply section, or equips its equipment with a port to which you can plug the connector of a standard plug-in power supply. The correct operation of the equipment may also require several voltages of different values. In this case, the developer must appropriately reduce or sometimes increase the input voltage.

Three power supply modes: voltage converter, voltage divider, linear stabilizer

There are basically three power supply methods: the power supply part can be based on a voltage divider, a linear stabilizer or a voltage converter. Each of these methods can be used to lower the voltage, but only the converter allows the voltage to be increased.

Voltage divider

The first way to implement the power supply part is based on a voltage divider. The operation of this circuit is based on Ohm’s law and the voltage deposited on a single resistor. By manipulating their values, any value of voltage can be obtained at the output, but it will be lower than the input voltage. However, this way of powering the device has some disadvantages. The first is current efficiency-the voltage divider is made of resistors with usually very low power. Any larger current will cause the resistor to burn quickly. Of course, you can use more powerful resistors, but this will greatly increase the price of this circuit. Another major disadvantage is that the design of the voltage divider always takes the specific input voltage into consideration. If it increases or decreases, the output voltage will also change.

Linear stabilizer

The linear stabilizer is another solution to reduce the input voltage. They are mainly produced in the form of three-leg components and are very common in consumer electronics. Their task is very simple-regardless of the input voltage, to maintain a constant voltage value at the output. Of course, it should be remembered that the input voltage must be higher than the output voltage. This type of component is characterized by low price, but it has heat dissipation problems. Any linear stabilizer must convert the difference between the input voltage and the desired output voltage into heat. This causes the components to heat up quickly even at low currents, so an additional heat sink must be used, which of course leads to higher costs.

Voltage converter

The third possibility of implementing a power system is based on a voltage converter. It consists of several basic components: coils, switching transistors, capacitors, resistors and silicon diodes. As you can see, the voltage converter is a more complex device than the previously described solution. There are several variants of them that can increase and decrease the output voltage in relation to the input voltage.

Voltage Converter

Why is it worth choosing a voltage converter?

One of the characteristics of voltage converters is that they are very useful in the process of designing electronic devices, that is, efficiency. As you already know, power loss is a major disadvantage of linear stabilizers. In this respect, converters are more economical. Every voltage converter has a parameter defined as efficiency, which is expressed as a percentage and refers to the ratio of the output power to the power obtained from the power supply. In other words, if the efficiency level of the device is 80%, it means that 20% of the power is lost in the form of heat dissipation mainly by the transistors and coils. However, it is important to know that the efficiency is not a constant, it depends on the working conditions of the converter, mainly depends on the power supply voltage, output voltage and load current.

In addition to the advantages, the voltage converter has a disadvantage, namely interference. Due to their design and working principle, the output voltage of inverters is not completely constant. If we need to power a circuit that requires a completely constant voltage, this may be a problem. In this case, it is necessary to place an RC filter at the output of the converter.

Due to its compact size and high efficiency, the voltage converter can be used almost anywhere. When designing any device, it is worthwhile to choose this type of component.

Voltage converter-how does it work?

A voltage converter is a pulse element. Simply put, it reduces the voltage by switching (alternating on and off). This process is very fast and will not interfere with the operation of the powered device or system. The element that controls the switch in a DC/DC converter is usually a MOSFET. However, in order for DC voltage to appear at the output of the device, additional components such as capacitors and inductors (chokes) are required. Although the capacitor only functions as a filter here, the task of the inductive element is to store energy while the device is working, so that it can be returned later. In addition, silicon diodes that control the direction of current flow must be placed in the converter circuit.

Voltage converter: type

There are several types of voltage converters on the market, the most popular ones are:

  • Buck converter-reduces the voltage,
  • Boost (boost) converter-increase the voltage,
  • Step-up / step-down (SEPIC) converter-to reduce or increase the output voltage.

Voltage Converter

In addition, there are other designs, the most interesting of which include:

  • Forward converter-a transformer-based DC/DC converter. It is a single switching element-the energy extracted from the power supply is transmitted to the output in real time. Due to the use of a transformer, the forward converter allows separation of input and output currents. Forward converters are used for switching power supplies and inverter welding machines with a power output of less than a few hundred watts.
  • Flyback converter-is a DC/DC converter that also uses current separation between input and output. This is a double switching device. In the first stage, energy is accumulated in the coil’s magnetic field and returned in the second stage. This type of system is mainly used for low-power switching power supplies.

Voltage converter: what should be considered when choosing one?

Choosing the right converter mainly depends on the equipment you are designing. If you want to design a small portable device, it is a micro converter worth considering. For larger devices, a larger size converter with a built-in heat sink can be used to facilitate heat dissipation. In addition, it is necessary to specify the type of converter required-boost, buck, or boost/buck.

If you want to minimize energy loss, it is worthwhile to equip yourself with a voltage converter that is as efficient as possible. The standard efficiency of this type of device is in the range of 80-95%. In addition, it is worth remembering the basic parameters of the converter, such as: maximum output current, output voltage range, and input voltage range.