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  • Release time: 2018 - 10 - 31
    Size400mmX400mmX80mmWeight4.2kg(/Plastic door/Not include suite )MaterialAluminumSingle cabinet suite numberNine modules per cabinetInstallationCrane girder hoisting and fixed installationColorBlack Cabinet 、Black 、blue and orange DoorWorking environmentBoth Indoor or OutdoorStandard accessories1 door 、2 positioning pins、1 electrical installation board、receive the card board、2 Connection pieces、3 quick lock
    Dimension400mmX400mmX80mmBox weight4.2kgTexture of materialAluminumUse environmentBoth indoor and outdoor.
  • Release time: 2018 - 10 - 31
    Size400mmX400mmX80mmWeight4.2kg(/Plastic door/Not include suite )MaterialAluminumSingle cabinet suite numberNine modules per cabinetInstallationCrane girder hoisting and fixed installationColorBlack Cabinet 、Black 、blue and orange DoorWorking environmentBoth Indoor or OutdoorStandard accessories1 door 、2 positioning pins、1 electrical installation board、receive the card board、2 Connection pieces、3 quick lock
    Dimension400mmX400mmX80mmBox weight4.2kgTexture of materialAluminumUse environmentBoth indoor and outdoor.
  • Release time: 2018 - 10 - 31
    Size400mmX400mmX80mmWeight4.2kg(/Plastic door/Not include suite )MaterialAluminumSingle cabinet suite numberNine modules per cabinetInstallationCrane girder hoisting and fixed installationColorBlack Cabinet 、Black 、blue and orange DoorWorking environmentBoth Indoor or OutdoorStandard accessories1 door 、2 positioning pins、1 electrical installation board、receive the card board、2 Connection pieces、3 quick lock
    Dimension400mmX400mmX80mmBox weight4.2kgTexture of materialAluminumUse environmentBoth indoor and outdoor.
  • Release time: 2018 - 10 - 31
    Module specificationCustomizableMaterial, size, colorCustomizableInstallation modeFast fixed installationScope of useIt can be used indoors and outdoors.
  • Release time: 2018 - 10 - 31
    Module specificationCustomizableMaterial, size, colorCustomizableInstallation modeFast fixed installationScope of useIt can be used indoors and outdoors.
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Technological house pouring money into each other: research on oscillation of LED display screen

date: 2018-10-22
Browse times: 8

The display effect and lifetime largely depend on the performance of the driver chip. When the LED screen factory imports the driver chip of the LED display screen, it pays more attention to the display effect, such as whether the low-gray display is consistent, whether the gradual transition is uniform, whether the oblique sweep has dark bright spots, open short circuit, and so on. These test items will be displayed to the terminal customers.


The test of display effect is the most important step, but also the first step.


A deeper understanding of the driver chip will enable us to have a clearer assessment of the performance and life of the LED display. Nowadays, more and more screen factory engineers begin to pay attention to the working environment and mode of the chip itself when they import driver chips. For example, the consistency of driving current, the consistency of REXT voltage, the peak of VDD chip, the waveform of driving port and so on.


Oscillation Phenomenon of LED Display Driver Port


The OUT driver port of the driver chip, which is directly connected with the LED lamp, is the core part of the driver chip. In view of the harm of oscillation to LED display, this paper will briefly introduce the port oscillation problem of some driver chips, and analyze its causes and improvement methods.


test method


The power supply is 5V40A with a single module. The module is lighted normally, and the oscilloscope probe is used to connect the grounding terminal of the module to the grounding access port, and the probe contacts the driving port of the driver chip.


test result


A mainstream driver chip in the market appears port oscillation phenomenon on modules with large interference (such as P10 static, etc.).


SM16016/SM16026 has no oscillation on the plate with large disturbance.


Oscillation of a mainstream IC on a plate with larger interference


Hazards of oscillation


The oscillation of the port brings many hazards:


Poor display effect


The constant current feedback loop in the chip can achieve the ideal constant current effect under stable working conditions. Port oscillation, chip can not achieve constant current. More importantly, this kind of chip which is easy to oscillate will still oscillate when it is low ash, which seriously affects the low ash effect. For full-color screens with high consistency requirements, the cost of constant-current chips is even worse than that of constant-voltage chips.


The service life of LED lamp is greatly reduced.


From the oscillation waveform, it can be seen that the negative pole of the LED lamp has been working under the quasi-sinusoidal wave with a voltage difference of 2V and a frequency of about 20MHz. Larger power supply spikes, transient high current and sustained extremely high frequency switching will reduce the life of LED lamps.


Large fluctuation of power supply reduces power supply life


If the 5V40A power supply works at full load, i.e. 40A current load, then for the power supply, the current change will be the continuous oscillation of ampere level current at about 20MHz. The output capacitor of DC power supply, under the condition of high frequency and large current fluctuation, generates equivalent internal resistance to heat, reduces service life, and then causes larger module peaks. It's not just the power supply that's damaged, it's all the components and driver chips in the module.


EMI exceeding standard


For the sinusoidal-like wave with a continuous frequency of 20 MHz, the current of each driving port changes from 0 mA to 40 mA, while the power supply oscillates continuously at 20 MHz with an ampere-level current. This will cause the dBuV value of the whole box to be superimposed at about 20 MHz frequency point, and ultimately lead to EMI easily exceeding the standard at that frequency point.


Abnormal noise of module capacitor


Capacitor noise is often caused by heat damage of capacitor. Similar to the power capacitor, port oscillation can easily cause capacitor damage and make abnormal noise.


Causes of oscillation and preventive measures


Cause of oscillation


The OUT port oscillation phenomenon is explained with the application scheme of constant current source driver chip as an example.


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