Low Pass Filters

The sbRIO-9687 provides a low pass filter for each analog input. The filter has two stages that are populated by default with 10 kΩ resistors and 3.3 nF capacitors. Refer to the sbRIO-9687 Specifications for details about the filter characteristics.

Figure 10. Simultaneous Sampled AI Input Low Pass Filter

1378

The first two filter resistors (R1) have a second functionality on the board and have a value of 10 kΩ. Other filter elements can be changed to set filter characteristics as required by the application. The R2 has a default value of 10 kΩ (0603 footprint), and C1 and C2 have a default value of 3.3 nF (0805 footprint).

Table 16. Filter Component Reference Designators
GPIC Input R2 C1 C2
AI0± R195, R207 C122 C121
AI1± R219, R227 C142 C141
AI2± R219, R226 C140 C139
AI3± R194, R206 C120 C119
AI4± R183, R170 C105 C104
AI5± R138, R153 C88 C87
AI6± R169, R182 C103 C102
AI7± R137, R152 C86 C85
AI8± R68, R75 C47 C46
AI9± R107, R118 C70 C69
AI10± R99, R116 C66 C65
AI11± R80, R66 C50 C49
AI12± R38, R50 C31 C30
AI13± R12, R24 C14 C13
AI14± R49, R37 C29 C28
AI15± R23, R11 C12 C11
Note For a different cut-off frequency, change only the filter capacitors while keeping C1 and C2 of equal value.