When the LED large screen where the ambient temperature is higher than the safe operating point temperature, LED large screen forward current will be beyond the safe area, so that LED large screen life greatly reduced or even damaged. The solution is to use the temperature compensation circuit to continuously reduce the LED forward current value, to prevent the LED large screen due to high temperature and damage. Today to introduce the LED large screen driver is how to complete the temperature maintenance.
First, LED large-screen drive temperature maintenance plan:
1, the use of LED large screen driver chip inside the overheating maintenance circuit off the LED driver output, forcing the LED to quell, to reach the cooling intention. The plan is only in the extreme case of LED large screen driver chip forced to adopt the overheating maintenance measures, can not ensure that the LED large screen for a long time stable operation.
2, after a suitable radiator LED large-screen chip to send out the heat in time to disperse, so that the chip temperature decreases. But the plan is in the depiction of large-screen LED pre-adopted a solution, and it is necessary to set aside to meet the margin, in practice it is difficult to ensure that both ambitious and economical role.
3, a special description of a large LED lighting with temperature measurement and control system. But because the cost is too high, it is difficult to LED large screen lighting a lot of popularization and application.
Second, the LED large-screen drive temperature maintenance principle: the NTC thermistor placed near the LED screen will be completed near the local temperature compensation function. When the LED large screen temperature increases, the resistance of the thermistor will be reduced when the LD pin voltage is lower than 0.24V. The current is controlled by the LD pin and the temperature compensation function is enabled.
Summary: LED large-screen driver is a high-power white LED (WLED), when the temperature is too high and the thermistor attack open or short circuit problems, will close the LED.