Luminous intensity refers to the overall brightness, from a lamp LED, for example, without regard to the area of the light source. Luminance indicates the degree of brightness over an area, such as from a display device. The greater the source area the higher the luminance. The luminance is normally obtained by dividing the luminous intensity by the light source area.
Reflow soldering is NOT recommended for most LED displays. The only exception is the LF series of surface mount displays. Dip or wave soldering is recommended for all other types (LA/LB/LAP/LBP). Please refer to the respective data sheets for further information.
Although possible, it is not recommended, since directly supplying voltage may, as we have seen above, result in an exponential change in output current, which can cause failure. Therefore, resistors should be connected to limit current.
One of the major factors that influence LED display life is die temperature – the lower the temperature the longer the life. In order to maintain low LED die temperature the following should be heeded: • Keep current flow small • Minimize ambient temperature • Design for sufficient heat dissipation
LED displays in general are not designed to be used outdoors. Adequate moisture treatment, temperature management, UV filtering, salt air protection, and the like should be provided if intended for outdoor use.
Yes, since LED numeric displays are not normally water resistant. However, this is at the user’s discretion and ROHM cannot provide advice or recommendations regarding this matter or guarantee the effectiveness of such treatments.
LED numeric displays, unlike discrete chip LEDs, are housed in larger packages, making them susceptible to damage during preheating. Therefore, it is recommended that preheating during the soldering process is conducted in such a way to ensure that the internal temperature does not exceed 100C. Also, the preheat time should be shortened.