Power supply ripple plays a crucial role in power modules and chips. Excessive ripple can directly reduce the efficiency of the power module, affect its conversion function, and even cause surge damage, leading to direct failure of the power module. Power supply ripple noise testing can assess the ripple situation, thereby improving the performance of the power module.
How is power supply ripple generated?
In layman's terms, power supply ripple is a phenomenon caused by voltage fluctuations in the power module. Generally, ripple in a power module is formed after the AC power has passed through the rectification and voltage regulation stages. Therefore, there will always be some AC interference in the DC output of switching power supplies and DC-DC power supplies. This interference is the internal ripple of the power module. Thus, power supply ripple is an unavoidable characteristic of power modules and cannot be completely eliminated. The only approach is to minimize the ripple as much as possible to reduce its impact on the power module.
Power supply ripple test principle
Through the concept of ripple, we understand that the hardware instruments needed to test the ripple of a power module include a power supply, an electronic load, and an oscilloscope. The power supply is responsible for providing the input voltage to the power module, allowing it to enter operating mode. The electronic load is responsible for measuring the rated operating current directly applied to the power module. Then, the oscilloscope is used to directly capture the waveform at the output terminal. The waveform captured by the oscilloscope is the ripple of the power module. At the same time, it is necessary to read the peak-to-peak value of the waveform; this voltage value is the ripple value of the power module. Usually, companies have strict requirements for the ripple value, which generally does not exceed 1% of the output voltage. For example, if the output voltage is 30V, the ripple value cannot exceed 30mV.
How to perform power supply ripple testing?
To test the ripple of a power module using ATECLOUD-POWER, you need to connect the hardware instrument and network in advance. Afterwards, you can simply log in to your ATECLOUD system account in your browser.
1. Run the power supply ripple test solution directly in the system. The system will automatically recognize the connected instruments and enter the test interface after confirming the instruments.
2. The test interface will directly display the test items, indicators, parameters, etc.; users can select one or more items to test simultaneously according to their needs, and can also freely configure the instrument parameters.
3. After selecting the project and configuring the parameters, enter the product number to start the test. The test will be completed within 3-5 seconds. The waveform images and indicators captured during the test will be directly displayed on the test interface.
4. After the test is completed, you can view the historical test data on the record report page. Data traceability is supported, and the data can also be directly exported as a data report without the need for manual recording and tabulation.
5. The data insight interface helps enterprises conduct comprehensive analysis of all data, including multi-dimensional analysis such as the number of product tests, product pass rate, indicator threshold distribution, and ripple change trend chart. It can also customize big data analysis dashboards according to user needs.
Nanosoft is a technology company specializing in the development of power module testing systems. The company has solved core pain points for many power module manufacturers, such as mass production line testing and overall maintenance of multiple projects. Nanosoft is a leader in domestic power supply testing automation.
Ripple and noise are important parameters for evaluating power supply quality, reflecting the instability and interference of the power output. Large ripple or noise can lead to system instability, increased sensor errors, and analog signal distortion. Therefore, correctly measuring and evaluating ripple and noise levels is crucial when designing and selecting a power supply.
This article will introduce how to test the ripple and noise of a DC power supply, and provide corresponding measurement methods and techniques. The AC stray components of a DC power supply output are called ripple and noise, or periodicity and random deviation (PARD), which are parameters describing power quality. The measured values are true effective values (RMS) or peak-to-peak values (Vpp), typically specified within a bandwidth of 20Hz to 20MHz. They reflect the instability and interference in the power supply output. However, their specific definitions and characteristics vary slightly.
Power ripple
Power supply ripple refers to the periodic changes or fluctuations present in the power supply output (see Figure 1). It typically exists in the form of an AC signal in the DC power supply output. Power supply ripple can be caused by factors such as power supply design and power supply filters, and may also be affected by load changes or other external interference. The frequency of power supply ripple is usually related to the power supply input frequency; for example, the ripple frequency of an AC power supply is 50Hz or 60Hz.
Power noise
Power supply noise refers to non-periodic random interference present in the power supply output (see Figure 1). These interference signals can originate from the internal electronic components of the power supply itself or from external environmental interference. Power supply noise is typically broadband and widely distributed across the frequency spectrum.
The magnitude of power supply ripple and noise is commonly measured in peak-to-peak value (Vpp) or true RMS value, measured in volts (V). It is crucial to determine whether the power supply ripple and noise values are peak-to-peak or RMS. Peak-to-peak values provide information about high-amplitude, short-duration spikes, while RMS values are helpful in determining the expected signal-to-noise ratio.
Both power supply ripple and noise affect circuit performance and system stability. Large ripple or noise can lead to system instability, increased sensor errors, and analog signal distortion. Therefore, when designing and selecting a power supply, it is necessary to consider the power supply ripple and noise levels according to application requirements and take appropriate measures to reduce their impact. Thus, accurately measuring power supply ripple and noise becomes crucial.
For DC power supplies, the electronic load used should operate in CR mode when testing ripple and noise. The ripple and noise specifications of the load should be lower than those of the power supply under test. This is especially important when measuring the ripple and noise of a power supply, as linear power supplies typically have excellent ripple and noise specifications; for example, Rohde & Schwarz's HMP series power supplies have voltage ripple and noise levels below 1.5mV (RMS). An adjustable AC source should be used to apply input to the power supply under test. Ripple and noise measurements should be performed at the specified minimum and maximum AC input, as well as the specified minimum and maximum source frequencies.
