Reduce the ripple of the power adapter, you can start from the following points.

Generally choose the reverse recovery time of the field effect tube to be 2 to 3 times slower than the diode D1, in order to avoid the formation of straight-through current, this current will generate a strong magnetic field, can increase the output noise interference, so you can artificially slow down the switching speed of the switching tube through the gate resistor R4.

3, The field effect tube DS end parallel RC


Can be connected in parallel with an RC circuit at both ends of the field-effect tube DS can also effectively reduce noise interference as shown in Figure 2, capacitor C2 is generally around 100P, the capacitance value will lead to increased switching losses in the field-effect tube, the resistance R2 is generally selected less than 10Ω resistance.



4, Reduce transformer leakage inductance


The use of sandwich winding method can make the primary and secondary winding coupling more closely, so that leakage inductance can be reduced, so as to reduce the purpose of noise.



5, The output diode ends in parallel with the RC


Diode in high-speed on and off, reverse recovery period, the diode's parasitic inductance and capacitance will generate high-frequency oscillations, in order to suppress high-frequency oscillations can be added to both ends of the diode RC buffer circuit shown in Figure 2, the resistance R3 generally in 1Ω ~ 100Ω, capacitance C3 generally in 100pF ~ 1nF, if the power supply operating frequency is low, efficiency to meet the requirements, diode D3 can be selected Reverse recovery time is slower diode.



6, The output plus two LC filtering


LC noise and ripple suppression effect is relatively obvious, according to the ripple frequency to select the appropriate inductor capacitance value, but due to the advantages of low price column inductor small size, so the general LC inductor will mostly choose column inductor, however, the column inductor is an open magnetic structure, the surrounding will produce more serious magnetic interference, we can use two inductors placed side by side, and the current flow in the opposite direction, that helps guide the magnetic flux from We can use two inductors placed side by side, and the current inflow direction is opposite, that is, it helps to guide the magnetic flux from one magnetic column to another, thus can reduce electromagnetic interference.

Learn more about power adapter information, please pay attention to Shenzhen BON Electronics Co.，LTD.

Shenzhen BON Electronics Co.，LTD. was founded in 2001, presently located in the most dynamic and creative Chinese city Shenzhen. As a well-established combination of R & D, manufacture and sale, the company specializes in power adapter and charger for digital communication product. Currently, the company has ISO9001 Quality Control System certification, international safety and environment-friendly certification of ETL, CCC，CE, RoHS and FCC, etc.


After more than ten-year operation with great concentration since establishment of the company, with our strict management, excellent R & D, high product reliability, customer-oriented service, as well as full support from our customers and various friends, our products sell to more than 100 countries and regions all over North America, South America, Europe, etc. Based on a good reputation and popularity with customer praise and confidence, BON has been a leading company in the industry.


With BON operation principle of Surpassing and innovation (Innovation beyond)and Double-win Based on Consistent Accumulation”, BON enterprise spirit of “Dedication, Ambitiousness, High-quality and Integrity”, BON has been consistently aiming at “Providing Technical Convenience and Happiness to More People with Double-win Policy”! BON Electronics expects sincere cooperation with all our customers in purposes of co-development and double-win.


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