Application Note 1805
October 2012
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Figure 2. DRF12XX Evaluation Board
A 5V max signal input is applied to (IN) via the BNC connector. Using the Power Ground (GND) for the BNC
shielding provides a ground connection for the input increasing noise immunity. Pins 2 and 6 (+VDD) are both
connected on evaluation board and are also connected internally to help balance pulse currents in the hybrid. Pin 3
(FN) is the invert or non-invert select Pin, internally held high (non-inverting) and must be jumpered on the
evaluation board (JP1) to ground to select the inverting mode.
Inputs Parameter Remarks
IN +5V max signal 50Ω coax, CMC suggested
50Ω coax, Rtn, CMC suggested
Tek P5100, CMC suggested on probe lead
Connected to MOSFET Source
Table 2
Table 2 shows Evaluation board inputs and outputs and the highly recommended Common Mode Chokes (CMC)
that should be used for the test bench set-up. This approach provides the best stability and the most accurate
measurements.
Construction of the CMCs are illustrated in Figure 3. The CMC on the left should be used for both the +15V input
and the +HV VDS input. These lines are tightly twisted pairs (5-8 twists per inch). The CMC on the right should be
used for the control signal Input and on the Scope Probe Cable. Three to five turns on each is sufficient. The CMCs
should be placed as close to the DRF12XX Evaluation Board as practical.