source:Industry News Popular:adapter release time:2022-05-18 10:07:11 Article author:yu
The switching power supply controls the time ratio of the switching tube on and off in the circuit, and maintains a stable circuit voltage output. It is a very common power supply design. But those who have been engaged in the design of switching power supply know that in the process of testing the switching power supply, some whistling sounds are often heard, similar to the leakage sound when the high voltage is bad, or the sound like the high voltage arcing. So when these phenomena occur, how should they be addressed?
Generally speaking, the reasons for the whistling of switching power supply generally have the following incentives.
Poor dipping of transformer
Includes unimpregnated varnish water. The whistling causes the waveform to have spikes, but the load capacity is generally normal. Special instructions: the higher the output power, the stronger the whistling, and the less powerful the performance is not necessarily obvious. A 72W charger product has had bad loading experience, and found in this product that there are strict requirements on the material of the magnetic core. In addition, when the design of the transformer is not good, it is also possible that the vibration will produce abnormal noise during operation.
PWM IC ground trace error
Usually, some products can work normally, but some products cannot be loaded and may not be able to vibrate. Especially when some low-power ICs are used, they are more likely to fail to work normally. For example, the SG6848 test board, because the performance of the IC was not thoroughly understood at the beginning, the layout was hastily based on experience, and the result was that the wide voltage test could not be performed during the test.
Optocoupler working current point wiring error
When the position of the working current resistor of the optocoupler is connected before the secondary filter capacitor, there is also the possibility of howling, especially when the load is more.
Ground Wire Error of Reference Voltage Regulator IC TL431
The grounding of the same secondary reference voltage regulator IC has the same requirements as the grounding of the primary IC, that is, they cannot be directly connected to the cold ground and hot ground of the transformer. If they are connected together, the result is that the load capacity is reduced and the howling sound is proportional to the output power.
When the output load is large, close to the power limit of the power supply, the switching transformer may enter an unstable state. The duty cycle of the switch tube in the previous cycle was too large, the conduction time was too long, and too much energy was transmitted through the high-frequency transformer; the energy of the energy storage inductor of DC rectification was not fully released in this cycle, and it was judged by PWM that in the next cycle There is no drive signal to turn on the switch, or the duty cycle is too small. The switch tube is in the off state in the entire cycle thereafter, or the on time is too short. After the energy release of the energy storage inductor for more than one whole cycle, the output voltage drops, and the duty cycle of the switch tube in the next cycle will be larger... This cycle will cause the transformer to generate a lower frequency (regular intermittent full cut-off). period, or the frequency with which the duty cycle changes drastically), producing lower-frequency sounds that can be heard by the human ear.
At the same time, the output voltage fluctuation will be larger than normal operation. When the number of intermittent full cut-off cycles per unit time reaches a considerable proportion of the total number of cycles, it will even reduce the vibration frequency of the transformer originally working in the ultrasonic frequency band, enter the audible frequency range, and emit sharp high frequencies. whistle". At this time, the switching transformer is working in a serious overload state, and there is a possibility of burning it at all times - this is the origin of the "screaming" before many power supplies burn out. I believe that some users have had similar experiences.
Read recommendations:
100-300W Charger,100W Charger,200W Charger,300W Charger
EI-28 AC ADAPTER LINEAR ADAPTOR Linear Power Adapter Switching Power Adapter Linear Adapter
3-8W Charger,3W Charger,8W Charger,4W Charger,5W Charger,6W Charger,7W Charger
Popular recommended products
200-500W Switching Power Supply
2020-08-2924-65W Switching Power Supply
2020-08-2912V2ASwitching Power Supply
2020-08-28MKD-571202000 ADAPTER AC ADAPTER CE ADAPTOR UL ADAPTOR Linear Adapter
2020-08-28MKA-571652420 ADAPTER AC ADAPTER CE ADAPTOR UL ADAPTOR Linear Adapter
2020-08-28EI-66 ADAPTER LINEAR ADAPTOR SWITCHING ADAPTOR Linear Power Adapter Linear Adapter
2020-08-28EI-57 ADAPTER LINEAR ADAPTOR Linear Power Adapter Switching Power Adapter INTERCHANGEABLE ADAPTOR Li
2020-08-28EI-48 ADAPTER LINEAR ADAPTOR Switching Power Adapter INTERCHANGEABLE ADAPTOR Linear Adapter
2020-08-28EI-41 ADAPTER AC ADAPTER LINEAR ADAPTOR SWITCHING ADAPTOR Linear Adapter
2020-08-28EI-35 ADAPTER AC ADAPTER SWITCHING ADAPTOR Linear Power Adapter Linear Adapter
2020-08-28ER42 High Frequency Transformer
2020-08-2712-36W POE POWER SUPPLY
2020-08-27Transformer,Power Transformer,Ring Power Transformer
2020-08-27Transformer,High Frequency Transformer,Frequency Transformer
2020-08-2712-24W Medical Switching Power Supply
2020-08-273-12W Medical Switching Power Supply 3W Switching Power Supply 12W Power Supply
2020-08-2745W PD Charger,45W Charger,PD Charger
2020-08-2736-90W Charger,36W Charger,90W Charger,40W Charger,50W Charger
2020-08-2724W USB Charger,24W Charger,USB Charger
2020-08-2724W 2USB Charger,24W Charger ,2USB Charger
2020-08-2710-24W Charger,24W Charger,10W Charger
2020-08-2730-500W LED Power Supply 30-500W Power Supply
2020-08-27Related Information
What are the conditions of use and maintenance methods for switching power supplies?
2022-05-21Some Frequently Asked Questions about Power Adapters
2022-05-20How to deal with the electromagnetic interference of switching power supply which is difficult in EM
2022-05-19Six situations and solutions that cause the whistling of switching power supplies.power supply price
2022-05-18Lightning Surge Test Method for Switching Power Adapters.adapter factory
2022-05-17Two common power adapter output overload protection methods.ADAPTOR price
2022-05-16Common fault maintenance skills of switching power supply
2022-05-14How should we choose the charger?
2022-05-13Power adapter expertise.CE ADAPTOR
2022-05-12How to solve the high temperature rise of switching power supply transformer?
2022-05-11The role of varistor in switching power supply
2022-05-10Structural characteristics and working principle of varistor
2022-05-09The role of varistor in switching power supply
2022-05-09What are the main components of switching power supply
2022-05-07Two ways for MOS devices to dissipate in high-power power supplies,CE ADAPTOR Processing
2022-05-06Several common insulation protection technologies for power adapters
2022-05-05What are the unique advantages of high frequency switching power adapter
2022-04-27What are the main components of switching power supply.China cnc plastic cutting
2022-04-26Troubleshooting method of switching power supply,CE ADAPTOR wholesale
2022-04-25How to use the power adapter correctly
2022-04-23What is the comparison between a charger and an adapter?
2022-04-23The optimal solution of drone power management solution!
2022-04-22Several common insulation protection technologies for power adapters
2022-04-21What are the unique advantages of high frequency switching power adapter
2022-04-20General Mechanism Analysis of Switching Power Adapter.ac power adapter wholesaler
2022-04-19Suppression method of low frequency ripple of switching power supply
2022-04-16Why is the power adapter making noise?
2022-04-15When the power adapter is in normal use, what is the normal temperature?
2022-04-1490% of people use the car charger incorrectly, are you using it right?CAR POWER SUPPLY sales
2022-04-13The difference between a power adapter and a voltage regulator
2022-04-12Popular recommended products
3-15W Switching Power Supply
2020-08-28MKS-1203000EX Switching Power Supply
2020-08-29MKD-571202000 ADAPTER AC ADAPTER CE ADAPTOR UL ADAPTOR Linear Adapter
2020-08-28MKS-1202000-36 Switching Power Supply
2020-08-2924W 2USB Charger,24W Charger ,2USB Charger
2020-08-27MKS-1201250HEU Switching Power Supply
2020-08-2945W PD Charger,45W Charger,PD Charger
2020-08-2719V2A 36W Switching Power Supply
2020-08-2812W 2USB Charger,2USB Charger,12W Charger,USB Charger
2020-08-2724-65W Medical Switching Power Supply
2020-08-273-12W Medical Switching Power Supply 3W Switching Power Supply 12W Power Supply
2020-08-27EI-35 ADAPTER AC ADAPTER SWITCHING ADAPTOR Linear Power Adapter Linear Adapter
2020-08-2812W CAR CHARGER,12W USB CAR CHARGER,CAR CHARGER,12W CHARGER
2020-08-2724-36W Charger,36W Charger,24W Charger,30W Charger
2020-08-2740W 4USB Charger,40W Charger,4USB Charger
2020-08-27EI-57 ADAPTER LINEAR ADAPTOR Linear Power Adapter Switching Power Adapter INTERCHANGEABLE ADAPTOR Li
2020-08-2812W POWER SUPPLY,12W CAR POWER SUPPLY,POWER SUPPLY,CAR POWER SUPPLY
2020-08-27EI Power Transformer Power Transformer
2020-08-27EI-66 ADAPTER LINEAR ADAPTOR SWITCHING ADAPTOR Linear Power Adapter Linear Adapter
2020-08-2860W 6USB Charger,60W Charger,6USB Charger,Charger
2020-08-2730-500W LED Power Supply 30-500W Power Supply
2020-08-2724W USB Charger,24W Charger,USB Charger
2020-08-27Inductance & Coil
2020-08-2710-24W Charger,24W Charger,10W Charger
2020-08-2712VDC8A 96W power supply
2020-08-283-100W PCBA power supply 3-100W Customized power supply 3-100W power supply
2020-08-2724-65W Switching Power Supply
2020-08-29EI-41 ADAPTER AC ADAPTER LINEAR ADAPTOR SWITCHING ADAPTOR Linear Adapter
2020-08-2812V2ASwitching Power Supply
2020-08-2836-90W Charger,36W Charger,90W Charger,40W Charger,50W Charger
2020-08-27