Vicor Autoranging MegaPAC AC-DC Switcher - Manual (Page 18)

UG:106 vicorpower.com Applications Engineering: 800 927.9474 Page 18
Interface Connections (Cont.)
+Sense/ –Sense -J2-2 and J2-3 (See page 10 for information on Autosense)
The +Sense on J2-2 should be connected to the +Power Out, and the –Sense on J2-3 to
the –Power Out terminal. Do not reverse or leave the Sense pins open. Sense pins can
be terminated locally at the output of the power supply, in which case the power supply
will provide regulation 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, this termination should be made close
to the output load. Compensation of up to 0.5 V (0.25 V per lead) can be obtained. Use
twisted pair 22-24 AWG wire for this purpose.
For DualPACs, the +Sense pins are available on connectors designated as J2A-2 and
J2B-2 for outputs A and B, respectively. –Sense pins are on J2A-3 and J2B-3, respectively.
These pins are also duplicated on the power connectors J1A and J1B.
Reminder: Only units with Autosense will automatically operate in Local Sense mode if no sense
connections are made. It wil operate in remote sense mode if remote sense connections are made.
Units without Autosense MUST have sense connections (Local or Remote) terminated to their respective
output for the unit to operate properly.
External Trim (J2-1)
Output voltage can be trimmed using an optional factory-installed Trim potentiometer
or with the Trim pin. The Trim potentiometer is located on the ConverterPAC. If the Trim
potentiometer has not been ordered, the Trim pin must be used. When using the Trim
pin, the Trim limits are determined by the DC/DC converter used on the ConverterPAC.
Maximum Trim ranges are 10% above the nominal converter voltage and 50% below
the nominal converter voltage (except 10 V, 12 V and 15 V outputs which are 10% below
nominal) as measured from the output studs or output connector of the power supply
as measured from the output studs or output connector of the power supply.
Note: The combined effects of module trim up, remote sense and dynamic load step may cause the
module to trip OVP. (See page 6 for information on restart).
The Trim pin on J2 can be used to control the output voltage. It is referenced to the
-Sense pin on J2 and can be controlled by either a resistor network or an external
voltage source. To increase an output voltage above its nominal, it is necessary to
increase the voltage at the Trim pin above the internal reference voltage (Vref). The
reverse is true to decrease an output voltage.
Note: Converters are sometimes pretrimmed at the factory if a nonstandard output voltage is requested.
Standard voltages include 2 V, 3.3 V, 5 V, 10 V, 12 V, 15 V, 24 V, 28 V, and 48 V. If using a nonstandard
voltage, or if a ConverterPAC is ordered with a Trim option, the resistor calculations will differ from those
on page 19. Please consult the factory for assistance.
Figure 9.
Sense Leads (Remote Sense)
Load
(Local Sense)
+P +Out
J2-2 +Sense
J2-3 -Sense
-P -Out
Use 22-24 AWG
Twisted Pair Wires
End of Life - Not Recommended for New Designs