Computer Hardware User Manual

3.5.2 Grounds and Returns
The “Returns” of the Dragonfly and Butterfly are structured internally in a star configuration.
The returns in each functional block are listed below:
Functional Block Return Pin
Power PR (Power Return)
Internal Switch Mode P.S. PR (Power Return)
Control section Internal, not accessible
Feedback SUPRET (J2/2)
The returns above are all shorted within the Dragonfly and Butterfly in a topology that results
in optimum performance.
1. When wiring the traces of the above functions, on the Integration Board, the Returns of
each function must be wired separately to its designated terminal on the Dragonfly and
Butterfly. DO NOT USE A COMMON GROUND PLANE. Shorting the commons on the
Integration Board may cause performance degradation (ground loops, etc).
2. Return Traces: The return traces should be as large as possible, but without shorting
each other, and with minimal cross-overs.
3. Main Power Supply and Motor Traces: The power traces must be kept as far away as
possible from the feedback and control traces.
4. PE Terminal: The PE terminal is connected directly to the Butterfly's heatsink or to the
Dragonfly's two PE strips on its lower board. In the Butterfly, the heatsink serves as an
EMI common plane. The PE terminal should be connected to the system's Protective
Earth. Any other metallic parts (such as the chassis) of the assembly should be connected
to the Protective Earth as well.
5. Under normal operating conditions, the PE trace carries no current. The only time these
traces carry current is under abnormal conditions (such as when the device has become a
potential shock or fire hazard while conducting external EMI interferences directly to
ground). When connected properly the PE trace prevents these hazards from affecting
the drive.
Follow these instructions to ensure safe and proper implementation.
Failure to meet any of the above-mentioned requirements can result in
drive/controller/host failure.
Dragonfly/ Butterfly Installation Guide Installation
MAN-DRBUIG (Ver. 1.1)
3-5