Skip to content
-
Working Principle: It stabilizes the output voltage by adjusting the conduction level of the internal transistor and changing its equivalent resistance. When the input voltage or load changes, it automatically adjusts the resistance to keep the output voltage constant.
-
Advantages: Simple design, low cost, good output voltage stability, low ripple factor, and less noise. It is suitable for circuits that are cost - sensitive and have high requirements for voltage stability.
-
Disadvantages: Relatively low efficiency. Especially when the difference between the input and output voltages is large, more power is dissipated on the regulating transistor and released as heat. Therefore, a heat sink is usually required. Moreover, linear regulators generally can only step - down the voltage and cannot increase the output voltage to a value higher than the input voltage.
-
Common Types:
-
78xx Series: Such as LM7805, LM7812. The "xx" represents the output voltage value. For example, LM7805 provides a + 5V regulated output. They are widely used in various electronic devices for providing a stable power supply to components such as microcontrollers, digital integrated circuits, and some low - power analog circuits.
-
79xx Series: These are negative voltage regulators. For example, LM7905 provides a - 5V output. They are used when a negative power supply is needed, such as in some audio amplifier circuits or operational amplifier applications that require a bipolar power supply.
-
Working Principle: Switching regulators use an inductor, a capacitor, and a semiconductor switch (usually a MOSFET) to convert the input voltage. The switch rapidly turns on and off, and energy is stored and released through the inductor and capacitor to achieve voltage regulation.
-
Advantages: High efficiency, especially when there is a large difference between the input and output voltages. They can handle a wide range of input voltages and can be used for both step - up (boost) and step - down (buck) voltage conversion, as well as inverting the voltage. They are suitable for applications where power efficiency is crucial and for portable devices to extend battery life.
-
Disadvantages: More complex design compared to linear regulators. They can generate more electrical noise due to the high - frequency switching operation. The output voltage may have more ripple, although this can be reduced with proper filtering.
-
Common Types:
-
Buck Regulators: These are step - down switching regulators. They reduce the input voltage to a lower output voltage. For example, a buck regulator might convert a 12V input to a 5V output. The output voltage is controlled by adjusting the duty cycle of the switching signal. They are widely used in power supplies for electronics such as laptops, mobile phone chargers, and DC - DC power converters.
-
Boost Regulators: As the name suggests, boost regulators increase the input voltage to a higher output voltage. They are used in applications such as battery - powered systems where a higher voltage is needed than the battery's nominal voltage. For example, a lithium - ion battery with a nominal voltage of 3.7V can be boosted to 5V to power USB - compatible devices.
-
Buck - Boost Regulators: These can both step - up and step - down the voltage depending on the input and output voltage requirements. They are useful in applications where the input voltage can vary widely and a stable output voltage is required regardless of whether the input is higher or lower than the desired output. For example, in some renewable energy systems where the input voltage from a solar panel or a wind turbine can fluctuate, a buck - boost regulator can ensure a constant output voltage to charge a battery or power a load.
