T = 25 ° C

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Second, the constant power control is to presuppose a constant power output, such as using nine 1W (= 3.4V,[link widoczny dla zalogowanych], = 350MA) of the LED in series with the PAR to be a 9W lamp, then the design time to be with P = 9W calculation. But in fact the will of each LED deviation deviation shown in Table 2.1: Tab2.1 LED Electrical characteristic (T = 25 ° C) can be seen from the table 2.1, although the deviation of each LED are not too large, But when the LED in series, the total deviation can not be ignored.
AR lamps may be more than the actual power of 9W or less than 9W,[link widoczny dla zalogowanych], directly reflected in the maximum brightness of the lamp is rated or not to be brighter than the rating. When the PAR lamp when the actual power of less than 9W, and drive the output power is still 9W, then the current flowing through the LED has been over rated, long-term work on the LED's life and color will have a certain effect. In addition, even if there is no bias LED factory,[link widoczny dla zalogowanych], as shown in Figure 1.2, with temperature and working time change,
when the change makes the LED's rated power is less than 9W, the long-term work will affect the use of LED life and color. Again, the power of compatibility issues. The constant power control mode are pre-configured output power, when the received light power and pre-set does not match the power, LED lights do not work. When the connection of the lamp power is less than the default power,[link widoczny dla zalogowanych], or even burned LED lights.