The quality of LED power supply directly restricts the reliability of LED products. Therefore, in the LED industry chain is gradually improved today, LED driver power supply as a high-performance guarantee for LED products, the role played in LED products is self-evident. 
First, test the electronic load of the LED constant current source:
At present, the traditional electronic load on the market can not fully meet the test requirements of the LED constant current source, and voltage and current instability will occur. This is determined by the characteristics of the LED constant current source itself. The current output by the LED constant current source Waveforms typically have large current ripples. For such characteristics, only the electronic load of the professional test LED constant current source can make the test result more accurate and ensure the quality of the product.
With the wide application of LEDs, some manufacturers have gradually introduced electronic loads for professional testing of LEDs. One of the most noteworthy is the ITECH IT8800 programmable high-precision electronic load series, which has a CR-LED function for professional testing of LED constant current sources. Its unique LED mode can be used for LED power supply testing. LED current, known as LED test experts. The characteristics of the LED constant current source will be carefully analyzed below and the working principle of the CR-LED will be described in detail.
Second, the characteristics of the LED constant current source:
We usually say that the LED constant current source output waveform usually has a large current ripple. It is precisely because of the existence of ripple that the CR mode of the traditional electronic load can not truly simulate the characteristics of the LED drive load, and the test voltage or current will continuously jitter.
The following is a diagram of the loaded circuit of the LED driver:
As can be seen from the above figure: If the test is performed in CV mode, the voltage of the load is constant and does not match the true voltage output waveform of the constant current source. Therefore, when testing the constant current source, the CR mode is selected more, but in the work, it will be found that the conventional CR mode may have a phenomenon that the test waveform does not conform to the actual situation, and even the voltage and current values ​​keep changing. The following are the problems and reasons for the traditional CR mode test I analyzed.
Third, the problems and reasons of the traditional CR mode test:
The LED can only be turned on in one direction (energized), called forward bias (forward bias). When current flows, electrons and holes overlap in it to emit monochromatic light. This is called electroluminescence.
Assume that the current value I0 output by the LED driver is 100mA, R=10Ω, and the diode conduction voltage Vd=30V. When the actual LED lamp is pulled, the output voltage of the LED driver is U0=100mA*10Ω+30V=31V, and the output is output. It is 31V/100mA. Assuming that the output current ripple of the constant current source is 10 mA, the output voltage ripple of the LED drive is 10 mA * 10 Ω = 0.1 V.
In the traditional CR mode test, the analog set CR value is 31V/100mA=310Ω. Similarly, the output current ripple of the constant current source is 10mA, and the output voltage ripple of the constant current source becomes 10mA*310Ω=3.1V. The voltage fluctuations are high and cannot work properly.
Fourth, professionally test the function of the electronic load of the LED constant current source - CR-LED:
The electronic load of the ITECH IT8800 series increases the diode turn-on voltage setting in the traditional CR mode, so that when the voltage applied across the electronic load is greater than the turn-on voltage of the diode, the electronic load works and is completely realistically simulated. The principle of diode operation. It is also simple and convenient to operate. It only needs to set the on-voltage value of the diode inside the instrument and set the CR value of the load to fully simulate the true characteristics of the LED lamp.
The following figure shows the waveform of the Idx IT8800 analog LED lamp when testing the LED constant current source:
in conclusion
Only professional testing of the electronic load of the LED constant current source can make the test results more accurate and ensure the quality of the product. Idex completely incorporates the characteristics of the LED constant current source into the design concept, and the CR-LED function developed can truly simulate the characteristics of the LED lamp. Meet the testing needs of many LED constant current source manufacturers, ensure the quality of LED products, and increase the powerful chips for enterprises in the increasingly fierce market competition.
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