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[ASEMI] The selection&margin of rectifier/diode when SMPS design

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[Original] How to choose the rectifier bridge model when designing the switching power supply? How to choose the Schottky diode model? How much is left? ASEMI engineers answer your questions


In the sales, customers often ask how much the rectifier bridge model should be left when the power supply design is reasonable. The rest of the rectifier bridge is left to be afraid of the bomber, and too much cost can not be left. ASEMI engineers summarize your analysis based on more than ten years of sales experience


ASEMI engineers dissect and analyze 3 common power supplies for you

As a power supply designer, have you encountered these problems: Do you know how to choose a rectifier bridge when designing a power supply? I don't know how much more is left in the end? The remaining amount is less than the fear of using the bombing machine, which affects the product brand; the remaining margin is too much to worry about the cost can not be reduced, the product loses competitiveness.

So how do you choose the rectifier bridge with the appropriate parameters and the corresponding Schottky diode in the power supply design? This problem is plagued by many beginners or new product development designers. Whenever our customers or procurement engineers ask us about this problem, we will help customers analyze and help customers choose the right rectifier bridge model.

Today, our ASEMI sales engineers are based on more than 10 years of product sales knowledge and the experience of many old projects with rich design experience. We will discuss, learn and share the rules with you. I hope that you will choose the rectifier bridge and Xiao in the future. The balance of the special base diode helps.

In the communication with the customer, the ASEMI sales engineer, in response to the customer's entangled rectifier bridge margin problem, through the following three common power anatomy analysis, and finally unified the rules

01、  5V 2A Phone Charger


Common 5V 2A mobile phone charger


Let's disassemble and see what type of rectifier bridge and Schottky diode are used inside.



The position of the ring 1 rectifier bridge, due to the problem of taking pictures of pixels, the actual specific model is MB6S or ABS10; among them, the position of the Schottky diode of the circle 2, the actual specific model is 10V45 or 15V50.

Of course, there are other manufacturers design, there are also disassembled and also sent to everyone to compare and compare


Through the above anatomy, we can find out that the output of 5V 2A is the mobile phone charger with output power: 5V*2A=10W (Watt). There are three common design ideas for the actual design of rectifier bridge reactor parameters: MB6S, ABS10, ABS210; actual design The Schottky diodes are: 10V45, 15V50, etc. If the power conversion factor is not considered, then the low-voltage part of the back-end Schottky diode output should be 10W (watt), and the high-voltage part of the front-end rectifier bridge must also have a power of at least 10W (watt) (assuming current X voltage = power) ): Then the current flowing through the rectifier bridge can be calculated accordingly: If the input voltage is 110V, then the input part current is 10W / 110V ≈ 0.1A; if the input voltage is 220V, then the input current is 10w / 220v ≈ 0.05A.


02、12V 2A Monitor or router power


Common 12V 2A monitoring power supply or router power supply


Open to see internal components


Of course, there are other design ideas, search for several models from the Internet.



Summary analysis: 12V 2A power supply, output power 12V * 2A = 24W, then the front end profit should be input at least 24W, the required current can be calculated Current = 24W / 110V or 220V ≈ 0.22A or 0.1A


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03、 19-24V 4-6A  Laptop  or all-in-one power supply


Common 19-24V 4-6A laptop  or all-in-one power supply ,like  one-machine adapter


Open and see components such as internal rectifier bridges and Schottky diodes

ASEMI肖特基管Summary analysis: 19V 6.32A power supply, output power 19V*6.32A ≈120W, then the front end profit should be input at least 120W, the required current can be calculated Current = 120W / 110V or 220V ≈ 0.5A or 1A



All of the above are calculated according to the power supply 0 loss, according to the theoretical conversion efficiency of 100%, the actual power conversion efficiency of 85%-95%, then the front-end rectifier bridge part of the input power is greater. We will summarize the rules in accordance with the theoretical situation, and properly enlarge some of them when designing:

First, calculate the output power of the power supply according to the output part; then calculate the power required by the front end input according to the output power, and then calculate the front end input current according to the input voltage;

The above input current and voltage are calculated, then the parameters of the required rectifier bridge are calculated according to the rectifier bridge current 3-5 times and the voltage is 3-5 times, and then the model of the rectifier bridge is selected accordingly.

The current and voltage of the output part are known. Then, according to the Schottky current more than 5 times, the voltage is 8-9 times to reserve the remaining amount, and the appropriate parameters are derived, and then the corresponding Schottky model can be selected according to the parameters.


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