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+SENSE/–SENSE (S1/S2 J2)
The sense lines for the outputs are shipped from the factory with Autosense. Autosense provides the
user with automatic sensing of the outputs. With Autosense, the PFC Micro™ will automatically operate
in a remote-sense mode when the remote-sense connections are made. But in the event that the
remote sense is not connected or needed, no local-sense selection is necessary – simply hook up the
outputs and the PFC Micro will automatically operate in local-sense mode.
In the local-sense mode (remote-sense lines not connected), the power supply will regulate the output
at the output terminals. The voltage appearing at the load may drop slightly due to voltage drop in
the power cables. If it is necessary to compensate for voltage drop along the output power cables, the
output can be trimmed up or configured for remote sense. Use stranded twisted pair 20 – 22AWG
wire for the remote-sense lines. Remote sense can compensate for a voltage drop of up to 0.5V, or
0.25V on each leg.
The sense connector for a single output board is a 3-pin connector providing the +SENSE connection
on S1/S2 J2-2 and the –SENSE connection on S1/S2 J2-3. The sense connector for a dual output board
is provided on the 18-pin output connector that also provides the output and trim connections. +SENSE
and –SENSE for the first output are located on S1/S2 J1-13 and S1/S2 J1-15, respectively. +SENSE and
–SENSE for the second output are located on S1/S2 J1-4 and S1/S2 J1-5, respectively. Remote sense is
not available for triple-output configurations.
External Trim (S1/S2 J2)
The trim pin at S1/S2 J2 is referenced to the –SENSE pin and can be used for external control of the
output voltage. For triple output cards, the Trim pins are available on S1/S2 J2-14, S1/S2 J2-6 and S1/S2
J2-3 for outputs 1, 2 and 3 respectively. For dual-output cards, the trim pins are available at S1/S2 J2-6
and S1/S2 J2-14 for outputs 1 and 2, respectively. For a single-output card, the trim pin is S1/S2 J2-1.
A 10% increase to the trim pin voltage will result in a 10% increase in output voltage. Reducing the
trim-pin voltage by 10% will result in a 10% decrease in output voltage.
Figure 7
Remote sense
Load
+OUT
+SENSE
–SENSE
–OUT
Use 20-22AWG
Twisted Pair Wires
Table 2
Module internal
reference voltages and
Thevenin resistances
Output Module
V
REF
R
TH
VI-200™/VI-J00™ ≥ 3.3V
2.50V
10.0kΩ
VI-200/VI-J00 < 3.3V
0.97V
3.88kΩ
Maxi (Predefined)
1.23V
1.0kΩ
Maxi (User Defined)
1.23V
Consult Factory
