接口数控端口和电阻激光驱动器-Interfacing Dig
ters in the application. The DS1847 resistor value is characterized at various temperatures in the Dallas factory. The result fits into an equation, whose coefficients are stored in registers for use during calibration at the customer site (refer to Application Note 167).
To illustrate some of the concepts described in the previous paragraph, Figures 4a, 4b, and 4c show typical characteristics in lasers and photodiodes after they are temperature compensated with look-up tables.
Figure 4a. A laser bias current variation is implemented with a look-up table if an open-loop operation such as Figure 1a is used.
Figure 4b. A peak-to-peak laser modulation current variation is implemented with a look-up table if an open-loop operation, such as Figure 2a, is used.
Figure 4c. An integrated photodiode current variation is implemented with a look-up table if a closed-loop operation (APC), such as Figure 3a, is used.
To illustrate some of the concepts described in the previous paragraph, Figures 4a, 4b, and 4c show typical characteristics in lasers and photodiodes after they are temperature compensated with look-up tables.
Figure 4a. A laser bias current variation is implemented with a look-up table if an open-loop operation such as Figure 1a is used.
Figure 4b. A peak-to-peak laser modulation current variation is implemented with a look-up table if an open-loop operation, such as Figure 2a, is used.
Figure 4c. An integrated photodiode current variation is implemented with a look-up table if a closed-loop operation (APC), such as Figure 3a, is used.
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