Що є п'ять головні джерела of the вихід ripple of the regulated power supply?
З the 20M осцилограф смуга пропускання as the limit standard, the voltage is set to PK-PK (ефективний значення is also measured), and the clip and ground wire on the oscillograph control head are removed (тому що the clip and the ground wire will form a loop, like an antenna receiving Noise, introduce some unneed noise), use a grounding ring (it is also possible not to use a a grounding ring, but the error generated by it should be considered), connect a 10UF electrolytic capacitor and a 0.1UF ceramic capacitor in parallel on the probe, and use an oscillograph The probe of the oscillograph should be tested directly; if the oscillograph probe is not directly in contact with the output point, twisted pair or 50Ω coaxial cable should be used for measurement.
The output ripple of switching power supply mainly comes from five aspects: input low-frequency ripple; high-frequency ripple; common-mode ripple noise caused by parasitic parameters; ultra-high-frequency resonance noise generated during switching of power devices; ripple noise.
Ripple is an AC перешкоди сигнал superimposed on a DC signal, and is a a very important criterion in power supply testing. Especially for power supplies for special purposes, such as laser power supplies, ripple is one of its fatal points. Тому, the test of power ripple is extremely important.
The measurement method of power supply ripple is roughly divided into two types: one is the voltage signal measurement method; other is the the signal measurement method.
Напруга сигнал сигнал вимірювання пульсація посилання до вимірювання змінного струму пульсація напруга сигнал накладення увімкнення постійний струм сигнал з ан осцилограф. для а константа напруга джерело?2c тест може безпосередньо використання a напруга зонд до вимірювання сигнал вихід до навантаження. для випробування з константа струм джерело, the voltage waveform at both ends of the voltage waveform at both ends of the sampling resistor is generally measured by using a voltage probe. По всьому the test process, the setting of the oscillograph is the key to whether the real signal can be sampled.
The follow settings are required before measurement.
1. Channel settings:
Coupling: the choice of channel coupling mode. Ripple is an AC signal superimposed on a DC signal, so if we want to test the ripple signal, we can remove the DC signal and directly measure the superimposed AC signal.
Probe: First choose the voltage probe method. Then select the attenuation ratio of the probe. It must be consistent with the attenuation ratio of the probe actually used, so that the number read from the oscillograph is the real data. For example, if the voltage probe used is set to ×10, then at this time, the option of the probe too to ×10.
2. Тригер налаштування:
Type: Edge
Source: the channel actually selected, for example, CH1 channel is going to be used for testing, then CH1 should be selected here.
Нахил: вгору.
Trigger mode: If you are observing the ripple signal in real time, select 'Auto' to trigger. The oscilloscope will auto follow the changes of the the actual measured signal and display it. At this time, you can also display the measured value you need in real time by setting the measurement button. However, if if you want to capture the signal waveform during a certain measurement, you need to the тригер режим до 'normal' trigger. At this point, it is is also required to set the size of the trigger level. Generally when you know the peak value of the signal you are measuring, set the trigger level to 1/3 of the peak value of the signal you are measuring. If not known, the trigger level can be set slightly lower.
Муфта: DC або AC... , зазвичай AC муфта.
3. Вибірка довжина (секунда/grid):
The setting of the sampling length determines the the required data can can be sampled. When the set sampling length is too large, the the high-frequency components in the the factual signal will be missed; when the set sampling length is too small, only part of the measured actual signal can be seen, and the the real actual signal cannot be gotained. Тому, in the factual measurement, it is required to rotate the button back and forth and observe utefully until the displayed waveform is a real and complete waveform.
4. Вибірка метод:
It can be set according to actual need. For example, if it is required to measure the P-P value of the the ripple, it is best to choose the peak measurement method. The number of sampling times can also be set according to actual need, which is related to the sampling frequency and sampling length.
5. Measurement:
By selecting the peak measurement of the corresponding channel, the oscillograph can help you display the required data in time. at the same time, you can also select the frequency, maximum value, root mean square value, etc. of the corresponding channel.
Через розумний налаштування і стандартизований операція of the осцилограф, the required ripple signal can be obtained. However, during the measurement process, care must be taken to prevent other signals from interfering with the oscillograph probe self, lest the measured signal is not true enough.
