Power module application test - power circuit - circuit diagram - Huaqiang Electronic Network

MOS power IC full range

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Test probe P100-M3

L0504-Murata muRata common mode inductor 90Ω 150mA

1. DC output module power supply ripple and noise test The output ripple of the DC output module power supply consists of two parts: common mode and differential mode. The differential mode ripple includes the switching frequency ripple and the high frequency noise far higher than the switching frequency. As shown in Figure 1. The former is mainly composed of switching frequency and harmonics, and the latter is mainly caused by rapid voltage and current changes of the power switching device, both of which are signals to be detected. Common mode noise is the output ripple caused by the potential difference of the grounding point. This signal flows in the same direction along the output line, and finally converts the load into a differential mode signal to affect the operation of the system. The same principle, during testing, if The impedance of the two signal lines of the probe is different, and the common mode signal is also converted into a differential mode signal, which affects the real ripple. The common mode signal has a great relationship with the grounding mode and can be suppressed by filtering measures. It is not the ripple test range of the module power supply. Only the test method of differential mode ripple is introduced here.




The low power module (=50W) output pin is connected to the parallel copper foil strip, followed by the capacitor. The 20MHz bandwidth oscilloscope is used to test and record the peak-to-peak noise voltage at the output; the length of the two parallel copper foil strips is 51mm and 76mm (2inch and 3inch). Between the two parallel copper foil strips between the distance is 2.54mm (0.1inch);

The distance between the position of the C solder joint and the output terminal of the module is 25.4mm (1inch), the contact point of the oscilloscope probe is shown in Figure (a), the test point is about 51mm from the output terminal of the module, and the thickness and width of the copper foil strip are two parallel copper. The sum of the foil strips ensures a voltage drop of less than 2%.
The high-power module (>50W) output pin is connected to the parallel copper foil strip, followed by the capacitor. The 20MHz bandwidth oscilloscope is used to test and record the peak-to-peak noise voltage at the output; the length of the two parallel copper foil strips is 51mm and 76mm (2inch and 3inch). Between the two parallel copper foil strips is 2.54mm (0.1inch); the distance between the C1 solder joint and the module module output terminal is 25.4mm (1inch), and the distance between the C2 solder joint and the oscilloscope probe is 12.7mm, C1 is a 1?F polyester capacitor or ceramic capacitor (X7R or X5R type) C2 is a 10?F tantalum capacitor. The oscilloscope probe point is shown in Figure (b), and the test point is 51mm from the module output terminal.
Left and right, the thickness and width of the copper foil strip (referring to the sum of the two parallel copper foil strips) ensure a voltage drop of less than 2%.
(2) Slowly adjust the output load, adjust from 0 to the rated load, and record when the peak-to-peak noise voltage at the output reaches the maximum value;
(3) Adjust the input voltage to the maximum and minimum values, and test and record the maximum value of the peak-to-peak noise voltage when the load changes within the empty full load range;
(4) Take the maximum of all the test values ​​as the peak-to-peak noise voltage.
This test method is accepted by most module power supply manufacturers and is preferred when conditions permit.