Selection of measuring instruments
To accurately measure the output voltage accuracy and ripple of the Power Adapter, you must first select a suitable measuring instrument. For the measurement of voltage accuracy, a high-precision digital multimeter can be selected, and its voltage measurement accuracy should be able to reach several decimal places to ensure the accuracy of the measurement results. For the measurement of ripple, an oscilloscope is required. The bandwidth of the oscilloscope should be wide enough. It is generally recommended to select an oscilloscope with a bandwidth not less than 10 times the switching frequency of the Power Adapter, so that the ripple signal can be accurately captured.
Construction of measurement environment
In order to obtain accurate and reliable measurement results, it is very important to build a stable measurement environment. The Power Adapter should be placed in an environment with good ventilation, relatively stable temperature and humidity, and ensure that its input voltage is stable and meets the rated input requirements of the adapter. At the same time, the wire connecting the Power Adapter and the measuring instrument should be as short as possible and have good conductivity to reduce the influence of line resistance on the measurement results. When measuring ripple, you should also pay attention to the grounding method of the oscilloscope probe. Single-point grounding should be used to avoid the formation of a ground loop to introduce interference signals.
Voltage Accuracy Measurement Method
When measuring voltage accuracy, set the voltage measurement range of the digital multimeter to a range close to the output voltage of the Power Adapter, then correctly connect the probe of the multimeter to the output terminal of the Power Adapter, and read the voltage value displayed by the multimeter. In order to improve the measurement accuracy, you can take the average value of multiple measurements and compare it with the nominal output voltage of the Power Adapter to calculate the voltage deviation. The smaller the deviation value, the higher the voltage accuracy. Generally, the output voltage deviation of the Power Adapter is required to be within ±5% of its nominal value.
Ripple Measurement Method
When measuring ripple, first connect the probe of the oscilloscope to the output terminal of the Power Adapter, and set the vertical sensitivity and time base of the oscilloscope so that the ripple signal can be clearly observed. Usually, the vertical sensitivity can be set to a few millivolts to tens of millivolts per grid, and the time base can be set to a few microseconds to tens of microseconds per grid. Then, use the measurement function of the oscilloscope to measure the peak-to-peak value or effective value of the ripple. It should be noted that since the ripple may contain high-frequency noise, in order to measure the ripple more accurately, you can set a suitable bandwidth limit on the oscilloscope to filter out the high-frequency noise signal and obtain a purer ripple signal for measurement. In general, the peak-to-peak value of the ripple of the Power Adapter should be controlled within a certain proportion of its output voltage, such as 1%-5%. The specific requirements vary depending on different application scenarios and devices.
