Circuit Design of Parallel Power Supply System of Switching Power Supply Module of C8051F340
Overview:
The system uses C8051F340 single-chip microcomputer as the control core. By sampling the output voltage and current, changing the PWM duty cycle output of the single-chip microcomputer and controlling the on-off of the MOS tube, the 8V DC/DC modules with two rated output powers of 16W are connected in parallel. powered by. After testing, the power supply system has a power supply efficiency of 70.57%; adjusting the load resistance, the sum of the output currents I1 and I2 of the two modules is 4 A, and I1 and I2 are automatically distributed in the 1:1 and 1:2 modes. The absolute value of the relative error is not more than 2%; it has the load short-circuit protection function and the protection threshold current is 4.5A.
In recent years, with the continuous improvement and rapid development of microelectronics technology and technology, magnetic materials science and sintering processing technology and other edge technology, switching regulator technology has also made breakthroughs. At present, multi-module parallel power supply has replaced the single centralized power supply and has become an important direction for the development of power systems. The parallel distributed power supply has the advantages of parallel expansion, high power density of the power module, small volume and weight, but also the problem that one or more modules operate in the current limit state due to the direct parallel connection of the power modules. . At present, current sharing control is a key technology for realizing high-power power and redundant power. In this paper, a photovoltaic grid-connected power generation simulation device is designed and fabricated, which realizes parallel power supply of dual-switch power supply modules, improves system power supply efficiency, and realizes automatic current distribution.
The design task designed and fabricated a parallel power supply system consisting of two 8 VDC/DC modules with rated output power of 16 W. The block diagram is shown in Figure 1. It is required to adjust the load resistance and keep the output voltage UO=8.0+0.4V, so that the sum of the output currents of the two modules is IO=1.0A and the current is automatically distributed in two modes: I1:I2=1:1 and I1:I2=1:2. The absolute value of the relative error of the output current of each module is not more than 5%; the sum of the output currents of the two modules is IO=4.0A and the current is automatically distributed according to the I1:I2=1:1 mode, and the output current of each module The absolute value of the relative error is not more than 2%; under the rated output power working state, the efficiency of the power supply system is not less than 60%; the system is required to have load short-circuit protection and automatic recovery function, and the protection threshold current is 4.5A.
Figure 1 Diagram of the associated power supply system
System overall design Parallel power supply system is mainly composed of controller module, DC/DC conversion voltage regulator module, current detection module and output voltage sampling module. The overall hardware block diagram of the system is shown in Figure 2. In the system, the DC/DC conversion voltage regulator module adopts a step-down chopper circuit that selects non-isolated mode; the current detection module derives the current value by sampling the voltage on the constantan wire; the C8051F340 single-chip output PWM wave adjusts the DC/DC module. Output, control output current.
Figure 2 system hardware block diagram
More about C8051F340: Integrated Circuit Query Network http://
(Please read the PDF for details)
PCB Stencil
PCB SMT Stencil,the unique goal is to move solder paste to the bare printed circuit board.
PCB Stencil, SMT Stencil, SMD Stencil, Laser Stencil, What is it?
Apart from all types of Printed Circuit Boards (PCBs) such as Prototype PCB, Aluminum PCB , HDI PCB , Flexible PCB , Rigid Flex PCB, Thick Copper PCB, High TG PCB , JHYPCB also manufactures solder paste stencils to meet Surface Mount Technology (SMT) requirements.
PCB Stencils, also called SMT stencils, SMD stencil, play a key role in transferring accurate amount of solder paste to correct positions on bare circuit boards ready for assembly. In other words, stencils can fast and efficiently ensure the most accurate solder paste amount and optimal electrical connection. With solder stencils, it is possible to use metal squeegee blades to apply solder paste easily over the openings on PCBs and make stencil to be well aligned with the surface of the advanced circuit board.
All of our SMT Stencils are 100% laser-cut type 304 full-hard stainless steel, ensuring the finest quality finish on the market today. We use a .001" laser beam with 98% overlap creating an extremely smooth hole that provides the best paste release. Most stencil fabricators use a .003" laser leaving mouse bites on the aperture edge. You can choose a PCB Prototype stencil, a frameless foil stencil, or a rigid permanently mounted stencil. Both the frameless and framed stencils come in various sizes to accommodate your printer and stencil requirements.
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| Prototype SMT Stencil Specs: | |
| Technology | 100% laser cut |
| Material Used | Stainless Steel |
| Stencil Thickness | 0.06 ~ 0.3 mm |
| Minimum Cut Width | 0.05 mm |
| Maximum Size | 736 X736 mm |
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| Allow for Fiducial Data | Yes |
| Delivery | 1 ~2 Day |
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- 24-hour turnaround standard
| Framed SMT Stencil Specs: | |
| Technology | 100% laser cut |
| Material Used | Stainless Steel |
| Frame Types | Cast, Space Saver |
| Stencil Thickness | 0.06 ~ 0.3 mm |
| Minimum Cut Width | 0.05 mm |
| Maximum Size | 736 X736 mm |
| Aperture Tolerance | within 0.007mm |
| Allow for Fiducial Data | Yes |
| Allow for Panelized Data | Yes |
| Delivery | 1 ~2 Day |
Framed PCB Stencil Specification
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Framed PCB Stencil Area |
Maximum Squeegee Area |
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300mm*400mm (11.81inch*15.75inch) |
120mm*220mm (4.72inch*8.66inch) |
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400mm*600mm (15.75inch*23.62inch) |
220mm*400mm (8.66inch*15.75inch) |
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400mm*700mm (15.75inch*27.56inch) |
220mm*500mm (8.66inch*19.69inch) |
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400mm*800mm (15.75inch*31.5inch) |
220mm*600mm (8.66inch*23.62inch) |
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400mm*900mm (15.75inch*35.43inch) |
220mm*700mm (8.66inch*27.56inch) |
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400mm*1000mm (15.75inch*39.37inch) |
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400mm*1200mm (15.75inch*47.24inch) |
220mm*1000mm (8.66inch*39.37inch) |
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400mm*1400mm (15.75inch*55.12inch) |
220mm*1200mm (8.66inch*47.24inch) |
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|
450mm*550mm (17.72inch*21.65inch) |
270mm*370mm (10.63inch*14.57inch) |
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500mm*800mm (19.69inch*31.5inch) |
320mm*600mm (12.6inch*23.62inch) |
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500mm*1200mm (19.69inch*47.24inch) |
320mm*1000mm (12.6inch*39.37inch) |
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550mm*650mm (21.65inch*25.59inch) |
340mm*440mm (13.39inch*17.32inch) |
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584mm*584mm (23inch*23inch) |
380mm*380mm (15inch*15inch) |
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Foil or Plate Only stencils are designed to work within interchangeable plate or "universal" systems. Also referred to as "reusable", these stencils do not need to be permanently glued into a frame.
Frameless SMT Stencils also referred to as foils are laser cut solder paste stencils designed to work with stencil tensioning systems known as reusable stencil frames. This type of stencil does not need to be permanently glued in a frame. Frameless stencils are significantly less expensive than framed stencils and provide money-saving storage while still delivering superior quality and performance.
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| Frameless SMT Stencil Specs: | |
| Technology | 100% laser cut |
| Material Used | Stainless Steel |
| Stencil Thickness | 0.06 ~ 0.3 mm |
| Minimum Cut Width | 0.05 mm |
| Maximum Size | 280 X 380 mm |
| Allow for Fiducial Data | Yes |
| Allow for Panelized Data | Yes |
| Delivery | 1 ~2 Day |
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For times when you need precise control for smaller production runs, our Foil or Plate Only stencils are ideal. These frameless stencils allow you to hand print with precision just the amount you need and can be stored conveniently.
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Electroformed SMT stencils are nickel-based, electroform foils permanently mounted in a stencil frame using a mesh border to tightly stretch the stencil foil taut in the frame. Electroformed stencils offer the best paste release characteristics available and are frequently used for fine pitch (20 mil to 12 mil pitch) SMT applications on printed circuit boards. They are also used for µBGA's, Flip Chip, and Wafer Bumping (12 mil to 6 mil pitch).
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| Electroformed SMT Stencil Specs: | |
| Technology | Electroforming |
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| Aperture Tolerance | within 0.007mm |
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| 0.06mm.0.08mm.0.1mm.0.12mm.0.13mm.0.15mm.0.18mm.0.2mm.0.3mm | |
| Positional Accuracy | ± 0.008mm |
| Delivery | 1 ~2 Day |
What's the difference between a framed stencil and a frameless stencil?
A framed PCB stencil will have a 0.5" to 1.5" thick metal frame around it, similar to a picture frame. Framed stencils are often used by contract manufacturers, assembly and board houses, and large scale production facilities and are commonly placed in a manual or automated stencil printing machine. Frameless stencils are a thin sheet of material cut with a small border around your design. For example pictures on these products, please visit our Gallery.
What's the difference between Polyimide and Stainless Steel?
All stencils are made with high quality Polyimide and Stainless Steel. We use only the industry leading Stainless Steel, designed specifically for stencils. These materials are ideal for prototype or Multilayer PCB.
Stainless Steel: 0.0007" Laser spot size, 0.001" minimum aperature size.
Polyimide Film: 0.003" Laser spot size, 0.005" minimum aperature size.
Polyimide has a lower precision rate due to the way it is processed and its ability to withstand heat during the cutting process. Minor variances will occur when the material reacts to the laser. Paste release is great, but this material should be limited to a small number of uses and with components 0402 or bigger.
The minimum aperature size for Polyimide is 0.005" vs 0.001" for Stainless Steel. Polyimide also has a natural curl in the material caused by the way the film is manufacturered, this is outside of our control. Stainless Steel provides the ultimate in precision and quality, with a 0.0007" spot size, and exceptional paste release with a truly flat surface. If you want the absolute best reflow experience, there is no comparison, Stainless Steel is the superior material.
Analysis and Treatment of Common Problems in PCB SMT stencil
- Insufficient solder paste
- Smudging/bridging
- Misalignment print
- Bow and twist
How to Determine Stencil Size?
Stencil size is composed by two parts: internal size and overall size. Internal size is the size compatible with that of PCB ready to be assembled while overall size refers to the size compatible with printer parameter limit. As long as both sizes are accurately designed, stencil will be able to make full use of its functions.
Internal size of stencil can be figured out conforming to the following rule:
- Width of Framed Stencil = width of PCB + 100mm while its Length = length of PCB + 100mm
- Width of Frameless stencil = width of PCB + 200mm while its Length = length of PCB + 200mm
For example, if one circuit board size is 50*50mm, then the size of its framed stencil should be around 150*150mm and the size of its frameless stencil should be around 250*250 mm.
It's easy to remember and operate so it worked for manual solder paste printing in SMT assembly prior to the advent of automatic printer. It can be said that different PCB sizes lead to generations of different internal sizes of stencil.
When it comes to automatic solder paste printer, however, it's relatively solid. Overall size of stencil has to be determined by parameter limit of the equipment, that is, printer, because stencil has to work within the range of printer with a frame. Different printers feature different parameter regulations. As far as PCBCart is concerned, the stencil size compatible with our printer can be either 650mm*650mm or 736mm*736mm.
PCB designers have to focus on internal size of stencil, they don't need to care about its overall size since it is generally determined by the parameters of printer in your contract assembler workshop.
How to Use PCB SMT Stencils?
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