Chassis Grounding Connections
The sbRIO-9637 provides a multi-function bracket that can be used with the supplied 4-40
grounding screw for directly attaching ground connections or for attaching to and grounding a
front panel as shown in the following figure.
Figure 9. sbRIO-9637 Chassis Grounding Screw
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1. Chassis Grounding Screw
The front I/O connector shields, chassis ground bracket, and mounting holes near the front I/O
are connected together internally to form chassis ground. Chassis ground is capacitively
coupled to digital ground near each of the IO connectors. For the best possible ESD protection,
connect chassis ground at the mounting holes or the chassis ground bracket to a low-
inductance earth ground.
When connecting the NI sbRIO device to external devices, ensure that stray ground currents
are not using the device as a return path. Significant stray currents traversing through the
NI sbRIO device can result in device failure.
To verify correct grounding of the NI sbRIO device, make sure the current flowing into the
power connector equals the current flowing out of the power connector. These currents should
be measured with a current probe after final assembly of the end system. Investigate and
remove any current differences.
Managing Thermal Conditions
Due to the small size of the sbRIO-9637, it is very important to appropriately dissipate the heat
generated during operation. You must plan for the thermal conditions of your application
throughout development and validation. This section provides design recommendations and
validation tools and methods for maximizing the thermal performance of the system.
Designing a Suitable Enclosure
NI sbRIO devices operate as components in a higher-level system and may require an
enclosure to protect the internal circuit card assembles and dissipate heat. For the sbRIO-9637,
the system integrator is responsible for designing an enclosure that meets the thermal
requirements of your specific application.
NI sbRIO devices integrated into an enclosure or system with proper thermal dissipation can
be deployed in high- and low-temperature environments. However, the 85 °C local ambient
operating temperature rating of the sbRIO-9637 does not mean that the external temperature of
the natural convection environment such as a room or larger enclosure can be 85 °C. In this
NI sbRIO-9637 User Manual
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