First, due to cost pressures, the production process cut corners and cut corners, eliminating the necessary product testing procedures, and the unqualified products were not eliminated in the factory and flowed to the market as shoddy products.

Second, the LED lamp bead has insufficient heat dissipation design margin, and the deviation of the assembly process and the incoming materials causes the lamp bead to overheat, and the forward voltage drop (Vf) drops out of control, causing the actual power of the lamp to deviate from the lower limit.

Thirdly, the thermal stability of the optional driving power supply of the lamp is poor, and the temperature drift of the output current is large, which directly causes the lamp power to deviate in a large range.

Fourth, in order to reduce the cost of purchasing LED lamp beads, the lamp beads purchase did not select the LED Vf distribution BIN according to the design requirements, which caused the actual LED power consumption to deviate from the design center value.

Fifth, the constant current accuracy of the optional drive power supply is low (generally 5%-8%), and it cannot be adapted to the Vf BIN with various lamp beads.