RIGOL switching power supply test scenarios

In recent years, electric and electronic equipment and people's work and life increasingly close relationship, PBX, telecommunication, electronic equipment, control equipment, etc. are already widely used the switch power, greatly facilitates switching power supply technology is developing rapidly.

In the high-frequency switching power supply, high reliability, low power, low noise, interference and modular development, but also on product design validation and functional testing to stricter requirements. This article will be internally test and measurement vendor RIGOL (Beijing Puyuanjing instrument science and technology co., Ltd.) as an example to explain some of the commonly used test switching power supply.

This test scenario used instruments are RIGOL DS1302CA digital oscilloscope and digital multimeter DM3064 and DG series function/arbitrary waveform generator.

Digital oscilloscope applications

1, transient signal measurement:

Load transient time is a dynamic time, it is the load current transient after switching power supply's output voltage stability to a predetermined time stable band.

Measuring signal, oscilloscope must have enough sample rate and waveform capture rate to effectively capture the needs of the waveform. We usually measure of response to s or ms level, while the DS1302CA RIGOL can measure minimum 1.2ns of rise time can capture the transient signal. Figure 2 reflects current by 0.1mA to 65mA process voltage transients.

　　

　　

　　

2. timely detection of harmful waveform signal

Power on delay is imposed AC input-output reached its adjustment range of time.

If you switch the power supply is turned on, some harmful waveform generation, that is likely to damage the switch transistor's current spikes. For the harmful waves, can inhibit the circuit to eliminate. By using the oscilloscope measurements, we can detect harmful waveform, and the instant of turned on the power to effectively suppress unwanted signal generation, indirectly raise the required power supply efficiency. Figure 3 is DS1302CA captured waveform.

　　

　　

　　

3, to reproduce the signal in the system

If you capture the incidental, instantaneous signal after more than satisfied with the signal analysis and calculation of simple, also hope to be able to reproduce the signal system, RIGOL digital oscilloscope and function/arbitrary waveform signal generator seamlessly interconnect you can provide the perfect solution.

DG3121A signal generator can be accessed directly through the dedicated interface DS1302CA waveform memory, resulting in signal generator reproduced on the burrs before capture or accidental signal waveform. Through this method, you can reproduce the signal for test measurements easier.

　　

　　

　　

4. simultaneous measurement of input and output signals

In switching power supply test often measuring circuit input and output, input and output voltage of a big gap between the operations a certain degree of difficulty.

DS1302A alternating measurement and analysis at the trigger input and output two signals, address the operational challenges. In the past in the midrange oscilloscope, dual-channel at display time is time base sharing, and now product available alternate trigger for the two channels have their own time base, and in the channel, you can select a different trigger mode. As Figure 5 shows, the two different signals, one Vpp = 188V signal, the other is a Vpp = 102mV signal, their frequency is 50 Hz and 20kHz respectively.

　　

　　

　　

5. capture ripple and noise analysis

Ripple and noise is constant in all other parameters, the specified bandwidth within the DC output voltage on its average deviation from the cyclical and randomness, it represents the adjustment and filter circuit behind DC output voltage of the remnants of unwanted exchanges and noise components.

Ripple and noise can use RMS or peak-peak, peak-peak measurement can provide the high amplitude, peak of short duration, and the valid values of information is beneficial to determine expected signal to noise ratio. Specifically, ripple that appears in the output terminal of a and input frequency and switching frequency synchronization components, with peak-peak (peak to peak) value indicates that the output voltage of 0.5%; noise that appears in the output terminals of the ripple outside a high-frequency components, with peak-peak (peak to peak) value indicates that the output voltage of 1%. Ripple and noise is the synthesis of both, with peak-peak (peak to peak) value indicates that the output voltage of 2%. The following is the ripple DS1302CA observation: the signal waveform

　　

　　

　　

Digital multimeter application programme

1. switch the power drift measurement

Drift mainly refers to the power supply output current or voltage of cycle and random deviation.

Switching power supply's drift measurement takes a long time, and on the high measuring accuracy requirements. Actual measurement we usually put all measurements from a statistical data, and then in the statistical value is calculated on the basis of its PPM values, total time, in 24 hours or so. This test procedure is not only boring but very prone to allow engineers to measure more convenient, and let the measurement error is reduced to minimum, RIGOL provides DM3064 multimeter with PC control solution.

　　

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Usually experiment, we should not only meet the test precision and test speed, high requirements to guarantee a certain amount of testing time.

Thus, if long-term unattended, they inevitably appear measurement errors. To resolve this problem, we can use computer software to control measurements for multimeter acquisition at intervals of voltage, current, and for the size of the period of time, the engineer can also be set arbitrarily, realize the data through a multimeter to easily capture. You can achieve all DM3064 up acquisition 200 000 data, if you want to store more data may choose stored directly into a USB disk or storage to the computer.

Use DM3064 convenience in data acquisition after its comes with software you can directly save the data, the data is saved as txt or mdb database file, so that with the help of mathematical analysis tools on the computer directly to the analysis of these data.

2. multi-channel inspection measurement

If we are not satisfied with the single measure that you want to implement multiple simultaneous measurements, you can select DM3064 data scan function for multiple inspection measurements, up to a 16-channel signal at the same time measurement.

Simultaneous measurement of each current and voltage output module, available through computer software statistics data, and then on every road statistics data for analysis.

If we want to see the data in the inspection time waveform, or you can open the waveform display, observation data inspection when data changes.

In waveform diagram, we can pass Ultralogger software on your PC very visually see voltage current change curve.

RIGOL multimeter for data logging and acquisition capabilities can quickly realize the current voltage of polling and data acquisition.

And software available through GPIB Ultralogger and USB bus-the-spot control, you can also control via LAN, and can put each workstation data report regularly returned to the remote server.

3, temperature measurement

Temperature measurement is power product testing, one of the most important part, now power products have to satisfy FEC, VDE, UL, CSA, FCC, and so on temperature measurement standard, so the temperature for the power supply is also one of the important measurement parameters.

With power technology advances, product temperature of increasingly high demands.

In the measurement process, you can use DM3064 multimeter with temperature sensor to the acquisition of physical signals into electrical signals, and then converted to the appropriate temperature value.

Similarly, if you want other applications, you can also use the corresponding sensor for measurement, select the collection features for fast sensor measurement capabilities.

Other application measurement

In switching power supply industry, need analog switch tube switching frequency and synchronization frequency to be measured, in this kind of product tests, we can increase the signal source to analog switching power supply in the different States of operation frequency.

You can also use the signal generator of signals to simulate the original control signal. In addition to this, we can select the DG3121A mentioned above, you can also choose DG2000 series and the DG1000 series signal sources. In addition, we can make the above instruments are integrated into the test system, the signal source, multimeters, oscilloscopes, power meter, bound together by software control can come to realize different performance and input-output characteristics of the test, and help you realize the production line of automated tests, as in Figure 10.