A DC regulated power supply is an electronic device that provides a stable and continuous power supply to a load. Most power supplies are AC power supplies, and when the voltage of the AC power supply or the load changes, the DC output voltage of the voltage regulator will remain stable.
I. DC regulated power supplies can be classified according to their operating mode as follows:
1. Controllable rectification type, the output voltage is set by changing the conduction time of the thyristor.
2. Chopper type: The unstable DC voltage input is used to change the on/off ratio of the switching circuit to obtain unidirectional DC, and then filtering is performed to stabilize the DC voltage.
3. Converter type: Unstable DC voltage is first converted to high-frequency AC by the inverter, then converted, corrected, and filtered. A sample is selected from the newly received DC output voltage. The inverter's operating frequency is controlled by feedback to achieve a stable DC output voltage target.
Although the filtered output DC voltage has good smoothness, its stability is still relatively low. The filtered power supply must produce a stable DC voltage to meet the requirements of electronic equipment.
II. Structure and Function of DC Regulated Power Supply
1. Transformer: Converts the main AC voltage U1 into an AC voltage U2 suitable for the load.
2. Rectifier circuit: Converts the unidirectional AC sinusoidal voltage U2 into pulse voltage U3.
3. Filtering circuit: A smoother surface tension U4 is obtained by filtering with high harmonics U3.
4. Voltage stabilization circuit: It ensures that the output voltage is not severely affected by power grid fluctuations and load changes, thereby maintaining the high stability of the UO DC output voltage.
The construction principle of a DC voltage control circuit:
The transformer converts the 220V AC main voltage to the required AC voltage value, and then converts the AC voltage to a unidirectional DC voltage. The voltage is further reduced by the rectifier and the pulse element through the filter circuit, so that the output voltage waveform is smooth.
After correction and filtering, the AC is converted to DC, and the stability of the DC output voltage is automatically maintained by the voltage stabilization circuit.
The design principles of power supply circuits often require professionals to identify and distinguish them, but power modules on the market are generally divided into bare boards and potted modules.
Bare board power modules: Bare boards are more intuitive and clear than potted ones. You can see from the surface that the electronic components are laid out in a reasonable and orderly manner, and the soldering lights are aesthetically pleasing.
Encapsulated power modules: While the internal components of these modules are not visible, their absence of exposed components results in better safety and performance. 2. Do the power modules use electrolytic capacitors or ceramic capacitors?
(1) Electrolytic capacitors and integral electrolytic capacitors can use sulfuric acid as the insulating medium. They have large capacity but small volume, and are marked with a + sign. They are usually used in low-frequency cross-linking and bypass filters, but have high dielectric loss.
(2) Ceramic capacitors include ceramic dielectric capacitors, ceramic capacitors, ceramic tubular capacitors, and ceramic semi-variable capacitors. They are primarily non-polar, require good dielectric materials, and have a limited capacitance; they are widely used in high-frequency circuits. 3. Observe the transformer components of the power supply module.
The transformer determines power output, high-temperature resistance, and other properties. The transformer is responsible for converting AC to DC and for saturating the circuit when energy is overloaded.
4. Observe the chip components of the power module. The core of the power supply is the IC, which is like the brain of the power supply. The quality of the IC directly affects the parameters of the power supply.
5. Randomly check the high-temperature aging test results of power modules. Regardless of the degree of control over product materials and production processes, it is necessary to check the aging process. The material inspection of electronic components and transformers is difficult to manage. Therefore, the quality stability of a batch of power supplies and the existence of potential safety hazards in materials can be checked by aging and high-temperature sampling of the entire batch of power supplies.
A power supply module is a power supply that can be directly mounted on a printed circuit board. Its key feature is its ability to power application-specific integrated circuits (ASICs), digital signal processors (DSPs), microprocessors, memory, field-programmable gate arrays (FPGAs), and other digital or analog loads. So, what should you consider when choosing a power supply module?
I. Rated Power
Theoretically, when selecting a power module, higher power is always better, as it ensures the system can operate under higher demands. However, higher power often means larger size and significantly increased cost. Therefore, when choosing a power module, it's best to select one with a power rating between 30% and 80% of the module's rated capacity. Within this range, the module's performance is generally stable and reliable, promoting long-term operation. Choosing an excessively high-power module is wasteful; choosing the right or too low power can overload the system, leading to instability or even component burnout. While some power modules are designed for overload operation, this should only be used as an emergency measure and not for long-term use. Ultimately, the choice depends on the specific product and requirements; choose the most suitable power module based on your product's characteristics and needs.
II. Packaging Form
Power modules come in various packaging forms. Some commonly used products conform to international standards, while many others are non-standard. Furthermore, products from the same company with the same power rating may have different packaging forms; conversely, products with the same package may have different power ratings. The appropriate packaging should be selected based on the specific requirements of your product. Generally, three points should be considered:
Given a fixed power rating, the package size should be as small as possible while still meeting the product's heat dissipation requirements. This facilitates size control and allows more space to be allocated to more important components. Of course, if size is not critical, a larger size can be chosen to increase the product's weight, which can also result in better heat dissipation.
Choose products that meet international standards whenever possible. These products have undergone extensive use and testing, making them relatively mature and reducing product development risks. Furthermore, it's easier to switch to a different brand of product that meets the same standards later, for any reason.
Ideally, it should be scalable to facilitate future expansion and upgrades. For example, with the same package, if a product is upgraded later, a higher-power package can be used while maintaining the same size and package, allowing for rapid product upgrades. Therefore, it's clear that the package type is chosen based on specific needs.
Especially for products with unique characteristics, manufacturers can be required to develop their own solutions to meet specific product requirements. This also helps prevent product plagiarism and protects the product to some extent. Continuous improvement through use further enhances the power supply product. Taking the power modules from WenGuDe Electronics as an example, their product series covers various packaging forms, including international standards, non-standard, and customized options. The products operate stably and can meet diverse user needs.
III. Temperature Range and Working Environment
Currently, power modules are mainly classified into commercial, industrial, and military grades. Different grades have different requirements regarding the environment, such as operating temperature, vibration, humidity, and dust. Therefore, when selecting module products, the environment in which the product will be used must be fully considered. Inappropriate selection will affect its use. Users should take these requirements seriously. If there are special requirements, they should consult with the technical engineers of the company to avoid affecting the progress of the work. There are two selection methods: First, select based on the power consumption and package type. If the actual power consumption is close to the rated power under the condition of a certain size (package type), then the module's nominal temperature range must strictly meet the actual needs and even have a slight margin. Second, select based on the temperature range. If a product with a smaller temperature range is selected due to cost considerations, but the temperature sometimes approaches the limit, what should be done? Derating is used. That is, select a product with a larger power or package size. This "overpowered engine for a small load" will result in a lower temperature rise, which can alleviate the contradiction to a certain extent. The derating ratio varies with the power rating, generally 3~10W/℃ for 50W and above. In short, you can either choose a product with a wide temperature range, which allows for more efficient power utilization and a smaller package, but is more expensive; or choose a product with a general temperature range, which is cheaper, but requires a larger power margin and package size. A compromise should be made.
For other special requirements, please contact our engineers to confirm the usage environment for your product.
IV. Operating Frequency
Generally, a higher operating frequency results in lower output ripple noise and better dynamic response. However, it also places higher demands on components, especially magnetic materials. Typical modular power supplies operate at switching frequencies below 300kHz, or even lower. Therefore, high-performance applications require products with higher switching frequencies.
V. Isolation Voltage
In general applications, the isolation voltage requirement for module power supplies is not very high. However, a higher isolation voltage can ensure that the module power supply has lower leakage current, higher safety and reliability, and better EMC characteristics. Therefore, the current industry standard for isolation voltage is above 1500VDC.
VI. Fault Protection Function
In other words, when a fault occurs in the external circuit of the power supply module, the power supply module should be able to automatically enter a protection state to prevent permanent failure, and should be able to automatically return to normal after the external fault disappears. The protection functions of the power supply module should at least include input overvoltage, undervoltage, and soft-start protection; output overvoltage, overcurrent, and short-circuit protection; and high-power products should also have over-temperature protection, etc.
Wide input voltage ratio 2:1 (maximum:minimum) Typical conversion efficiency 84% Wide operating temperature range: -40~85℃ Flame retardant compliant with UL94-V0 requirements (plastic case only) Input and output isolation voltage: 1500Vdc Output short circuit and overcurrent protection (auto-recovery) Copper case (E7) / Plastic case (E2) Output voltage accuracy: Main circuit ±1%, Auxiliary circuit ±3% Ripple and noise (20MHz, nominal input voltage): Vo≤5.0V, ≤50mVp-p; Vo≥48V, ≤180mVp-p; Other, ≤100mVp-p Product warranty 5 years Output voltage can be manufactured for any voltage between 3.3-48VDC.
VII. Power Consumption and Efficiency
Under a given output power, the lower the module loss (P_dissipation), the higher the efficiency, the lower the temperature rise, and the longer the lifespan. Besides the normal full-load loss, two other losses are worth noting: no-load loss and short-circuit loss (module power loss when the output is short-circuited). Lower losses indicate higher module efficiency, especially since a short circuit, if not addressed promptly, can persist for an extended period; lower short-circuit loss significantly reduces the probability of failure. Of course, lower losses also better meet energy-saving requirements.
