We only deepen understanding of the driver chip, LED display can make the performance and life of a better evaluation results. Driver chip OUT drive port, directly connected with the LED lights, is the core part of the driver chip. But it will also exist port shock phenomenon. If this happens, will bring a lot of harm to the LED display, then as Jue Guangxu simple analysis of the hazards and preventive measures.
First, we need to know how to test the port-driven shocks. Connect the probe to the ground terminal of the module and the probe to the drive port of the driver chip. If there is a large chip driver chip interference phenomenon, then there is a port shock problem.
Secondly, we need to understand the shock to the LED display which harm:
1, the display is poor
As the chip constant current feedback loop, only in a stable working condition, in order to achieve the desired constant current effect. If the port shocks, then the chip can not reach constant current. The higher the consistency of the requirements of the full-color, the company spent a constant flow of chip money, but with a constant pressure chip produced by the effect of even worse.
2, the module capacitance abnormal sound
Capacitive noise is often due to damage caused by capacitance heat. Similarly, in the power capacitor, the port will be more likely to cause vibration of the capacitor damage and abnormal noise.
3, LED lamp life significantly reduced
We can learn from the shock waveform, LED lamp cathode has been in the voltage difference of 2V, frequency of about 20MHz class sine wave work. Larger power spikes, instantaneous large current, continuous high frequency switch will reduce the LED lamp life.
4, power fluctuations will reduce power supply life
If the 5V40A power load work, that is, 40A current load, then the power is concerned, the current change will be amperage current around 20MHz continuous shock. DC power output capacitor, the higher the frequency of high current fluctuations, resulting in a strong heat, resulting in lower power life, but also caused a larger module spikes. So damage is not just the power, but also includes all the components on the module and the driver chip.
Finally, from the above analysis shows that the measures to avoid port shocks:
1, the module traces optimization, reducing parasitic inductance, as far as possible using ground, power line copper way, but limited by board space constraints, improve the space is not.
2, the drive chip stability, the replacement of a better stability of the driver chip, from the source to avoid the shock appears.
3, the module capacitance increases, will bring the cost increase.