Download the app

The difference between a buck regulator and a boost regulator

Encyclopedia
10/04/2024

Function and output voltage direction


Step-down regulator


The main function of a step-down regulator is to reduce a higher input voltage to a lower stable output voltage. For example, the common 12V DC input voltage is converted into a stable output voltage of 5V or 3.3V to meet the needs of low voltage power supply such as mobile phone chargers and some chips on the computer motherboard.


Boost voltage regulator


The boost voltage regulator is to increase the lower input voltage to the higher stable output voltage. For example, in some devices that use single or multiple dry batteries (1.5V or 3V, etc.) for power supply, the voltage can be raised to 5V, 9V, etc., through the boost regulator, in order to power circuits or devices that require higher voltages, such as portable loudspeakers and some handheld measuring instruments.


Circuit structure and working principle


Step-down regulator


  • Basic circuit structure: The common buck regulator adopts the buck converter structure. It is mainly composed of power switching tubes (such as MOSFET), inductors, capacitors, diodes and control circuits.


  • Working principle: When the power switch tube is on, the input voltage charges the inductor, the inductor current rises linearly, at this time the diode is reversed off, and the load is powered by the capacitor; When the switching tube is cut off, the inductor generates a reverse electromotive force, which supplies power to the capacitor and load through the diode, and the inductor current decreases linearly. By controlling the on-off and cut-off time (duty cycle) of the switching tube, the output voltage is adjusted to keep the output voltage stable.


Boost voltage regulator


  • Basic circuit structure: The boost converter structure is usually used, and also includes power switching tubes, inductors, capacitors, diodes and control circuits.


  • Working principle: When the power switch tube is on, the input voltage is added to both ends of the inductor, the inductor current rises linearly, at this time the diode is cut off, and the capacitor is discharged to the load to maintain the output voltage; When the switching tube is off, the reverse electromotive force generated by the inductance is superimposed with the input voltage, charging the capacitor through the diode and supplying power to the load. By adjusting the on-off and cut-off time (duty cycle) of the switching tube, the output voltage can be raised and stabilized.



Application scenario


Step-down regulator


  • Consumer electronic devices: widely used in mobile phones, tablets, laptops and other devices. Most of the chips and circuit modules inside these devices require a variety of low-voltage levels of power supply, and the power input of the device (such as lithium battery voltage or external adapter voltage) is relatively high, and a step-down regulator is needed to meet the voltage requirements of different components.


  • Power adapter: Used to convert the mains to a lower DC voltage output, such as the common 220V AC mains to 5V, 9V, 12V DC voltage, for mobile phones, routers and other devices to charge or power.



Boost voltage regulator


  • Portable devices: For portable devices powered by low-voltage batteries (such as dry batteries, button batteries), use when some components in the device require a higher voltage. For example, some flashlights powered by a single 1.5V dry battery boost the voltage to 3V or higher with a boost regulator to provide brighter lighting.


  • Renewable energy system: In the solar photovoltaic power generation system, when the photovoltaic cell output voltage is low at low light intensity, the boost regulator can raise the low voltage to a voltage level suitable for subsequent circuits (such as inverters) to improve the utilization efficiency of solar energy.


Efficiency characteristic


Step-down regulator


In the process of buck, the efficiency of buck regulator is related to the difference of input and output voltage, the load current, the performance of circuit components and other factors. Generally speaking, when the difference between input and output voltage is small, the efficiency is relatively low in the case of light load (small load current), and the efficiency will be improved with the increase of load current. However, if the difference between input and output voltage is too large, the efficiency will also be reduced due to the influence of power loss (mainly the loss of components such as switching tubes and inductors).


Boost voltage regulator


The efficiency of the booster regulator is also affected by many factors. Because in the boost process, the inductor needs to store more energy to raise the voltage, and the diode will have a certain energy loss in the reverse cutoff, so in the case of low input voltage, high output voltage and heavy load (large load current), the efficiency may be greatly affected, but with the development of technology, new boost regulators are also constantly improving efficiency.


Topics
Machines Electrical Drives
Encyclopedia

The Electricity Encyclopedia is dedicated to accelerating the dissemination and application of electricity knowledge and adding impetus to the development and innovation of the electricity industry.

Cost Differences and Performance Comparison of 35kV New Energy Transformers Based on Dry-Type, Mineral Oil, and Vegetable Oil
Cost Differences and Performance Comparison of 35kV New Energy Transformers Based on Dry-Type, Mineral Oil, and Vegetable Oil
For users, when purchasing a 35kV new energy transformer, choosing between dry-type, mineral oil-filled, or vegetable oil-filled types involves multiple considerations. These include user habits, maintenance-free performance, safety and fire resistance, volume and weight, among others. However, cost differences are undoubtedly one of the most crucial factors.To illustrate the issue intuitively, this paper selects a three-level energy efficiency dual-winding new energy transformer with a rated ca
Ron
07/26/2025
What is the connection group of a transformer?
What is the connection group of a transformer?
Transformer Connection GroupThe connection group of a transformer refers to the phase difference between the primary and secondary voltages or currents. It is determined by the winding directions of the primary and secondary coils, the labeling of their start and end terminals, and the connection mode. Expressed in a clock-like format, there are 12 groups in total, numbered from 0 to 11.The DC method is commonly used to measure the transformer's connection group, mainly to verify whether the con
Vziman
07/26/2025
What is the sequence for powering down the transformer?
What is the sequence for powering down the transformer?
The sequence for shutting down a main transformer is as follows: when de-energizing, the load side should be shut down first, followed by the power supply side. For energizing operations, the reverse order applies: the power supply side is energized first, then the load side. This is because: Energizing from the power supply side to the load side makes it easier to identify the fault range and take prompt judgment and handling measures in case of a fault, preventing the fault from spreading or e
Rockwell
07/26/2025
What are the methods for switching operations of station transformers?
What are the methods for switching operations of station transformers?
Let's take an auxiliary power system with two station transformers as an example. When one station transformer needs to be out of service, there are two operation methods: non-interruptive power supply and instantaneous power interruption. Generally, the method of instantaneous power interruption on the low-voltage side is preferred.The operation method for instantaneous power interruption on the low-voltage side is as follows:Open the 380V power incoming circuit breaker of the corresponding sec
Vziman
07/26/2025
Source professional electrical partners, experts, and explore smart grid & energy solutions.
Inquiry
Download
IEE-Business is dedicated to serving the personnel in the global power industry.
Join IEE-Business, not only can you discover power equipment and power knowledge, but also canhnd like - minded friends!
App Store App Store App Store App Store App Store App Store App Store App Store
App Store