Compiled version: V1.0
1. AC-DC power module performance test items and test methods
-Test circuit
1.1 The maximum power of the test module;
Generally, the maximum output power is mentioned in the specifications of AC-DC power modules, and the load size is calculated according to its output voltage, and the load meter is used to simulate the test.
※The maximum continuous output power of the AC-DC power supply module must not exceed the nominal maximum value, otherwise it will cause permanent damage to the module.
1.2 Light load test;
Calculate the 10% light load size according to the following formula.
1.3 Test module output voltage accuracy (from Jinshengyang Application Guide);
1.4 Linear voltage adjustment rate test (from Jinshengyang application guide);
1.5 Load regulation test (from Jinshengyang application guide);
1.6 Conversion efficiency (from Jinshengyang Application Guide);
Conversion efficiency of AC-DC module power supply: The input terminal cannot directly use the multimeter to test the product of voltage and current as the input power. Generally, a power meter is used to directly read the input power Pin; the output terminal uses the actual output load value Iout and output voltage value Vout calculates the output power.
Note: The input is AC mode. Due to the existence of inductance and capacitive reactance inside the product, the phase difference between the input voltage and current and the distortion of the input current waveform are caused.
1.7 Ripple and noise test (from Jinshengyang application guide);
Ripple and noise are periodic and random AC components superimposed on the DC output. It also affects the output accuracy. Generally, peak-to-peak measurement (mVp-p) is used for ripple and noise.
The first step is to set the bandwidth of the oscilloscope to 20MHz, which can effectively filter out high-frequency interference coupled into the environment;
The second step is to use parallel wire test method, twisted pair method or rely on test method.
The following figure is the circuit by test method
Since the ground clamp of the oscilloscope will receive various high-frequency noises and interfere with the measurement results, in order to better reduce the impact of such interference on the test results, a reliable test method can be used. The actual test ripple and noise will vary depending on the circuit and external components.
1.8 Isolation and insulation characteristics (withstand voltage and insulation strength);
-Withstand voltage test method:
According to the withstand voltage test standard, slowly increase the withstand voltage value from 0. When it is adjusted to the set value, it will be maintained at the set value for one minute.
-Insulation strength test method:
Short-circuit the input and output pins respectively, and add an isolation voltage (DC or AC peak value, according to the isolation voltage given by the product) between the input and output to test for 1 minute.
1.9 Protection features (input overvoltage protection, output overcurrent protection and output short circuit protection);
-Output overcurrent protection
Adjust the output voltage of the AC-DC power supply module, the input voltage is the rated value, the output current is 110%, and then gradually reduce the load resistance or increase the load current until the output is short-circuited, test and record the output current and voltage value when the power supply module starts to overcurrent .
-Output short circuit protection
When testing the output short-circuit protection function, keep the output short-circuit state for at least 30 minutes (the time can be reduced appropriately, 30 minutes is the standard time), and then cancel the short-circuit state to restore the power supply to normal operation.
1.10 The above performance test after high and low temperature.
Test whether the AC-DC power supply works normally after being stored in a high and low temperature environment.
Note: AC-DC test is a dangerous experiment. Pay attention to placing the AC-DC module in a black box for testing, and only lead out the test pins to prevent dangerous accidents
2. Basic principles of AC-DC power supply selection
2.1 Determine the input source type of the AC-DC power supply module
First determine whether the input source is AC or DC, or AC and DC input conditions.
2.2 Determine the input voltage range and select the standard reference voltage
Confirm the input voltage range first, and leave enough margin when designing and selecting.
2.3 Determine the output voltage of the AC-DC power supply module
The number of output groups has single output or dual output.
2.4 Determine the output power of the AC-DC power supply module according to the size of the load
After the load is determined, the output current is basically determined. The AC-DC power module is best used at 30% to 80% power at room temperature.
2.5 Choose the isolation properties of AC-DC power modules
The isolation feature makes the input and output of the AC-DC power supply module independent power supplies, and the multiple outputs are isolated independently and do not share the ground.
2.6 Determine the package size of the AC-DC power supply module
The AC-DC power supply module needs to reserve enough space to consider the interference of heat radiation on the signal, as well as the impact of the electromagnetic interference of the module on the performance of other circuit components, taking into account the considerations of volume, cost, and delivery.