User Manual
點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC. DM163
8x3-CHANNEL CONSTANT CURRENT LED DRIVERS Version: A.004 Page 17
Driver Output Current (Cont.)
Figure 13. Vout vs. Output Current
The curve shown in Fig 12 is the average result of a large number of samples. Due to
chip-to-chip variation in Vrext, users may observe a different Iout-Vout curve than above.
However, the curves of VDD=5v and VDD=3.3v should be close to each other when the same chip
is tested because DM163 utilizes a negative feedback circuit to keep the average voltage of Vrext
pins close to constant, regardless of the VDD. Therefore, the Iout-to-Rext curve should not be
seriously influenced by VDD variation.
The Fig 13 illustrates the relation between Vout and Iout. Iout is the constant value when Vout
exceeds the voltage of turning point. In other words, Iout is independent of the fluctuation of Vout
if IC is biased in this condition.