Analysis Of The Causes Of Large Ripple In The Power Supply Of Commonly Used Electronic Equipment

By Author: Luosi
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I. Introduction

In the design and production process of electronic equipment, power supply ripple is a problem that cannot be ignored. Large power supply ripple will not only affect the stability and reliability of the equipment, but also may cause damage to the equipment. Therefore, how to solve the problem of large power supply ripple has become an important task in the design and production of electronic equipment. In this paper, we will focus on the problem of power supply ripple, from the cause analysis, hazardous effects, solutions and other aspects of the detailed discussion, in order to provide useful reference for the relevant technical personnel.

Second, the causes of power ripple analysis

Power ripple causes mainly include the following aspects:

The instability of the power supply itself: voltage regulator and rectifier power supply and other power supply equipment may have a certain instability in the work, resulting in output voltage fluctuations. This instability may come from a variety of factors such as design defects in the power supply equipment, poor manufacturing process, component ...
... aging and so on.

Power supply load changes: when the load current changes, the power supply may not be able to immediately provide a stable voltage, resulting in fluctuations in the output voltage. Such fluctuations may be caused by the lack of responsiveness of the power supply equipment to load changes, or the load itself has a non-linear characteristic and other reasons.

Power Line Transmission Loss: There is a certain amount of resistance and inductance in the power lines, which may cause voltage fluctuations when power is transmitted through these lines. In addition, components such as connectors and plugs in power lines may have problems such as contact resistance and poor contact, further exacerbating voltage fluctuations.

Interference with the power supply: Nearby electronic equipment may interfere with the operation of the power supply, causing output voltage fluctuations. This interference may come from other electronic equipment electromagnetic radiation, electrostatic interference and many other factors.

Third, the harmful effects of large power ripple

Power ripple on the harm of electronic equipment is mainly manifested in the following aspects:

Reduce power supply efficiency: power ripple will lead to reduced efficiency of the power supply equipment, increasing energy consumption and operating costs of equipment.

Damage to equipment: stronger ripple will cause surge voltage or current generation, resulting in burning appliances and damage to equipment.

Affect the performance of equipment: power ripple will affect the stability and reliability of the equipment, reducing the performance and service life of the equipment.

Interference with digital circuits: power ripple will interfere with the logic of digital circuits, affecting their normal operation, and even lead to equipment failure.

Produce noise interference: power ripple will also bring noise interference, so that the image equipment, audio equipment can not work properly.

Fourth, the solution of power supply ripple

For the power supply ripple problem, can be solved from the following aspects:

Increase the output inductance and output capacitance for filtering

This is a simple and effective solution. By increasing the value of output capacitance can delay the on-time, increase the regulation time of the power supply, so as to achieve the purpose of reducing ripple. In practice, generally choose large-capacity low ESR polymer aluminum electrolytic capacitors as the output capacitance. In addition, a capacitor can be connected in parallel near the current input to provide current to further improve the filtering effect.

Add a level of LC filter line on the output side

The LC filter has a more significant effect on noise ripple suppression. According to the ripple frequency to be removed to select the appropriate inductance capacitance composition filter circuit, generally can be very good to reduce the ripple. The sampling point should be selected before the LC filter to ensure the effectiveness of the filtering effect.

After the switching power supply output connected to the LDO filtering

LDO filtering is one of the most effective ways to reduce ripple and noise. Its output voltage is constant and does not require changes to the original feedback system. However, this method is more costly and consumes more power, and is generally applicable to high-end switching power supplies that require high-precision output, such as signals from servers, medical equipment and other high-precision instruments.

Increase BUCK output capacitance

Increase the switching frequency of the power supply chip

Increasing the high-frequency ripple frequency is conducive to suppressing the output high-frequency ripple. However, too large a switching frequency is likely to cause excessive EMI radiation, so it is best to choose a suitable value for the switching frequency. In practical applications, trade-offs and choices should be made according to specific needs and equipment characteristics.

V. Conclusion

Large power supply ripple is one of the common problems in the design and production of electronic equipment. Through in-depth analysis of its causes and hazards, and take the corresponding solutions, can effectively reduce the impact of power ripple on the equipment, improve the stability and reliability of the equipment. In practical application, appropriate solutions should be selected according to the specific needs and characteristics of the equipment, and continuously optimize and improve the design to further improve the performance and service life of the equipment.

This paper discusses the problem of large power supply ripple in detail and proposes a variety of solutions. However, due to space constraints, this paper fails to elaborate on all the details one by one. It is hoped that this paper can provide useful reference and inspiration for relevant technical personnel, and provide effective solutions to the power ripple problem in the design and production of electronic equipment.
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