Vicor PFC MegaPAC-HPEL Power Factor Corrected AC-DC Switchers - Manual (Page 20)

UG:119 vicorpower.com Applications Engineering: 800 927.9474 Page 20
External Trim (J2-5/P2-5)
Output voltage can be trimmed using an optional factory-installed Trim potentiometer
or with the Trim pin (see Figure 11). 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.
Note: The combined effects of module trim up, remote sense and dynamic load step may cause the
module to trip OVP. (Tripping OVP will require cycling input power to the supply off, then on).
The Trim pin on J2/P2 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.
If using a nonstandard voltage, or if a ConverterPAC is ordered with a Trim option, the resistor
calculations will differ from those on Page 21. Please consult the factory for assistance.
Output Module Vref RTH
VI-200/VI-J00 ³3.3 V 2.50 V 10.0 kW
VI-200/VI-J00 < 3.3 V 0.97 V 3.88 kW
Maxi (Pre-Defined) 1.23 V 1.0 kW
Maxi (User Defined) 1.23 V Consult Factory
Figure 11.
External Trim
(Remote Sense)
Load
+P +Out
P2-7 +Sense
P2-6 -Sense
-P -Out
Use 22-24 AWG Twisted Pair Wires
R5
V Ref
P2-5
R6
R8
R7
To Error
Amplifier
R4
R3
R2
R1
+
+
V
2
V 1
-
-
RTH
Use 22-24 AWG
Twisted Pair Wires
Table 1.
Module Internal
Reference Voltages and
Thevenin Resistances.