VICOR DC MegaPAC User manual

UG:123 Page 1
DC MegaPACTM
DC-DC Switcher
USER GUIDE | UG:123
Overview
The DC MegaPAC DC-DC switcher allows users to instantly configure high efficiency power supplies.
Although small in size (6.0 x 11.7 x 3.4in) [153,4 x 296,7 x 85,8mm]), the DC MegaPAC provides up to
1600W of output power with up to 16 isolated outputs.
A complete power supply is configured by selecting and inserting up to eight slide-in output assemblies
called “ConverterPACs™.” ConverterPACs incorporate one or two Vicor DC-DC converters and are
available in a wide array of outputs and power levels. The net result is a power supply that offers the
advantages of a custom supply, but is assembled from standard and modular building blocks.
The entire family of MegaPAC power supplies is completely user-configurable. If output requirements
change, i.e., more power or a different output voltage is needed, upgrading is easy: simply unlock
a single screw and replace the slide-in ModuPAC™assembly with one that has the desired rating.
For additional flexibility, ModuPACs can be connected in parallel to increase output power (booster
ModuPACs), or in series for higher voltages. The driver is to the left of the boosters when looking at the
output end of the supply. A user-friendly interface provides control and output sequencing capability, in
addition to useful status indicators. Please consult our Applications Engineering Department if you have
other special requirements.
S
NRTL
CUS
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®
Contents Page
Overview 1
Standard Features 2
Optional Features 2
Mechanical Considerations 2
MegaPAC™ Dos and Don’ts 3
Technical Description 3
ConverterPAC™ Functional
Description 5
Configuring and Reconfiguring
MegaPACs™ 6
Pin Identification 7
Mechanical Drawings 7
Part Numbering 8
Quick Install Instructions 9
Interface Connections 11
Specifications 17
Temperature Derating 18

UG:123 Page 2
Standard Features
 DC Input: 12VDC (10 – 20VDC), 24VDC (18 – 36VDC), 36VDC (21 – 56VDC),
48VDC (36 – 76VDC), 72VDC (55 – 100VDC)
 Output Power: 1600W; 1 – 16 outputs
 Full power output to 45°C; half power to 65°C
 Soft start for limiting inrush current
 Conducted EMI meets BTR 2511
 Output Sequencing and General Shutdown
(Consult Applications Engineering for automatic sequencing circuitry).
 Remote Sense capability and output overcurrent protection on all outputs
 Output overvoltage protection on most outputs
 Output overtemperature protection on all outputs
 Input Power OK status signal
 Input over, under and reverse voltage protection
 Box-to-box paralleling capability
 Input temperature monitor, warning, and shutdown
 CE Mark, UL, CSA
Optional Features
 DC OK status signal
 Output voltage adjustment range with built-in potentiometer
 Reversed fan airflow direction
 Industrial-grade screening of output converters
 Hardwired Local Sense
Mechanical Considerations
The DC MegaPAC™can be mounted on any of four surfaces using standard 8-32/M4 screws. The
chassis comes with four mounting points on each surface; maximum allowable torque is 20lb.in. The
maximum penetration is 0.15in [3,8mm].
When selecting a mounting location and orientation, the unit should be positioned so airflow is not
restricted. Maintain a 2in [5,1cm] minimum clearance at both ends of the DC MegaPAC and route all
cables so airflow is not obstructed. The standard unit draws air in at the fan side and exhausts air out
the load side. If airflow ducting is used, avoid sharp turns that could create back pressure. The fan
moves approximately 30CFM of air.
Avoid excessive bending of output power cables after they are connected to the DC MegaPAC. For
high-current inputs and outputs, use cable ties to support heavy cables minimizing mechanical stress
on output studs. Be careful not to short-out to neighboring output studs. The DC MegaPAC is supplied
with serrated, flanged hex-nuts on all output studs, so LOCTITE®or lock washers are not required.
The maximum torque recommended on flanged nuts is 45lb.in. Never loosen the inner nut on a
ConverterPAC™. This nut supports the hardware inside the ConverterPAC and is factory torqued.
Avoid applications in which the unit is exposed to excessive shock or vibration levels. In such
applications, a shock absorption mounting design is required.

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MegaPAC™ Dos and Don’ts
 Do not leave ConverterPAC™Sense lines open. Always terminate them locally or at the load. Use
twisted pair 22-24AWG wire.
 Always fill all output slots of the MegaPAC. If a slot is not filled with a ConverterPAC, it should be
filled with an airblock. Failure to do so can result in overheating and damage to the power supply.
 Do not unplug ConverterPACs while input power is applied. They are not designed for
hot-plug applications.
 Do not restrict airflow to the unit. The cooling fan draws air into the unit and forces it out at the
output power terminals.
 For power expansion use booster ConverterPACs. Viewing the unit from the output terminal side,
always insert boosters to the right side of the driver.
 Run the output (+/–) power cables next to each other to minimize inductance.
 Wait five minutes after shutting off power before inserting or removing ConverterPACs.
 Do not attempt to repair or modify the power supply in any manner other than the exchange of
ConverterPACs as described in this manual.
 Insert proper fault protection at power supply input terminals (i.e., a fuse).
 Use proper size wires to avoid overheating and excessive voltage drop.
 Never loosen the inner nut on a ConverterPAC.
 Verify output nuts are tight before powering up.
Technical Description
The DC MegaPAC chassis consists of an EMI filter, cooling fan, customer interface and associated
housekeeping circuits. Input DC voltage (+VIN, –VIN, and GND) is applied to the input connectors. The
input current is passed through an EMI filter designed to meet conducted British Telecom specifications.
At start up, inrush current is limited by a thermistor. The thermistor is shunted out shortly after initial
power up by a relay driven by a DC bus voltage sense circuit. The DC voltage is then fed to the
backplane. The backplane supplies power to a variety of ConverterPAC assemblies that provide the
desired low-voltage, regulated outputs.
Voltage conversion in the output assemblies is achieved by the Vicor family of Zero-Current Switching
(ZCS) DC-DC converters. These are forward converters in which the main switching element switches
at zero current. This patented topology has a number of unique attributes: low switching losses; high
frequency operation resulting in reduced size for magnetics and capacitors; excellent line and load
regulation; wide adjustment range for output; low EMI/RFI emission and high efficiencies.
At initial power up, the DC MegaPAC outputs are disabled to limit the inrush current and to allow
the DC bus potential to charge to the operating level. A low-power flyback converter operating with
PWM current-mode control converts the DC bus into regulated low voltage to power the internal
housekeeping circuits and DC cooling fan. When operating on 48VDC, the internal housekeeping VCC
comes up within 3s after the application of input power. Once the input range is within specification,
the Input Power OK signal asserts to a TTL "1" indicating the input power is OK, and allows the power
outputs to be enabled. The power outputs will be in regulation 500ms after the Power OK signal asserts
to a TTL "1." An auxiliary VCC output of 5VDC sourcing up to 0.3A is provided for peripheral use.

UG:123 Page 4
An output Enable/Disable function is provided by using an optocoupler to control the gate In pins of
the ConverterPAC™assemblies. If the Enable/Disable control pin is pulled low, the optocoupler turns
on, pulling the gate IN pin low and disabling the ConverterPAC output. The nominal delay associated
for an output to come up when measured from release of the Enable/Disable pin is 5 – 10ms. The
General Shutdown function controls all outputs simultaneously and works in a similar manner. If driven
from an electromechanical switch or relay, a capacitor should be connected to eliminate the effects
of switch bounce.
There is no ride-through (hold up) time available with the DC MegaPAC™.
Figure 1
DC MegaPAC Architecture
EMI Filter
Under, Over & Reverse,
Voltage Protection,
Inrush Current Limiting
Logic Power
Supply
Housekeeping
Circuits
DC
Fan
DC Bus Sense
Customer Interface
(Opto-isolators)
Power
Input ConverterPAC #1
ConverterPAC #2
ConverterPAC #3
Power
Output
ConverterPAC #5
Control
ConverterPAC #4
Under, Over &
Reverse Voltage
Control
Power
Output
Power
Output
Power
Output
Power
Output
ConverterPAC #6
ConverterPAC #8
ConverterPAC #7
Power
Output
Power
Output
Power
Output

UG:123 Page 5
ConverterPAC™ Functional Description
ConverterPACs are the family of slide-in output assemblies used in MegaPAC™power supplies.
ConverterPACs are interchangeable within a MegaPAC so they can be added, moved or changed as
necessary. They are also interchangeable between different AC input MegaPAC chassis. A ConverterPAC
removed from a Mini MegaPAC could be used in a three-Phase MegaPAC, for example. ConverterPACs
can be selected with a variety of options and in voltages from 2 – 95VDC.
ModuPAC™
The ModuPAC output assembly consists of a VI-200 DC-DC converter that converts the high-voltage bus
to the desired regulated output voltage. Each ModuPAC can provide up to 200 watts of power. Multiple
ModuPACs can be paralleled in a driver-booster configuration to provide more power. ModuPACs are
fused with a PC-Tron, DC-rated, fast-acting fuse. A passive LC filter is used to reduce output ripple/noise
down to 1% typical, and 2% maximum peak-to-peak from 10% to 100% of rated load. An optional
DC Power Good signal or output voltage Trim potentiometer can be specified. The ModuPAC contains
overvoltage protection (OVP), overcurrent protection (OCP), and overtemperature protection (OTP). The
OCP has automatic recovery when the overcurrent condition is removed. The OVP and OTP are latching
functions and require recycling of the AC input power to restart.
DualPAC™
This output assembly consists of two VI-J00 DC-DC converters that convert the high-voltage bus to the
desired regulated output voltages. Each output on a DualPAC can provide up to 100 watts of power
and is fused with a single PC-Tron, DC-rated, fast-acting fuse. A passive LC filter is used to reduce output
ripple/noise down to 1% typical and 2% maximum peak-to-peak from 10% to 100% of rated load. An
optional output voltage trim potentiometer can be specified. DC Power Good signal is not available. The
DualPAC contains overcurrent protection, which recovers automatically when the overcurrent condition
is removed. Overvoltage and overtemperature protection are not available.
JuniorPAC™
The JuniorPAC consists of one VI-J00 DC-DC converter that converts the high-voltage bus to the desired
regulated output voltage. JuniorPACs can provide up to 100 watts of output power and are fused with
a single PC-Tron, DC-rated, fast-acting fuse. A passive LC filter is used to reduce output ripple/noise
down to 1% typical, and 2% maximum peak-to-peak from 10% to 100% of rated load. An optional
DC Power Good signal or output voltage trim potentiometer can be specified. The JuniorPAC contains
output overcurrent protection, which recovers automatically when the overcurrent condition is removed.
Overvoltage and overtemperature protection are not available.
RamPAC™
This output assembly consists of a VI-J00 DC-DC converter with a Ripple Attenuator Module (RAM) and
is designed for applications requiring low-output ripple/noise. The RamPAC can attenuate the ripple/
noise down to 10mV peak-to-peak over a 20MHz bandwidth from 10% to 100% of rated load of the
converter. Each RamPAC can provide up to 100 watts of output power, and outputs from 5 to 50V are
available. An optional DC Power Good signal or output voltage trim potentiometer can be specified. The
RamPAC contains output overcurrent protection, which recovers automatically when the overcurrent
condition is removed. Overvoltage and overtemperature protection are not available.
+
_
Remote Sense
VI-200
Output Adjust
–VOUT
+VOUT
DC OK (Power Good)
+
_
VI-J00
Remote Sense
Output Adjust
–VOUT
+VOUT
DC OK (Power Good)
Remote Sense
Output #2 Adjust
Output #2
Output #1
Remote Sense
Output #1 Adjust
VI-J00VI-J00
+
_
VI-J00 RAM
Remote Sense
Output Adjust
–VOUT
+VOUT
DC OK (Power Good)
ModuPAC
JuniorPAC
DualPAC
RamPAC

UG:123 Page 6
Configuring and Reconfiguring MegaPACs™
ConverterPACs™can be easily added, replaced or moved by sliding the assemblies in or out of a
MegaPAC chassis. Most ConverterPACs are Driver ModuPACs™and can be inserted into any available
slot. For outputs greater than 200 watts, a Driver ModuPAC and one or more Booster ModuPACs will
be used. Arrays of Drivers and Boosters should be configured so all Boosters are placed in the slots to
the immediate right of the Driver when looking at the output end of the MegaPAC.
Prior to removing or installing ConverterPACs, you must remove power from the MegaPAC
and wait five minutes. Failure to do so can result in personal injury or damage to the supply.
Take standard ESD precautions when handling ConverterPACs.
Removing ConverterPACs
ConverterPACs can be removed by loosening the captive screw at the base. Once this screw has been
loosened, the ConverterPAC will slide out of the chassis. Once a ConverterPAC has been removed, the
empty slot MUST be filled with either another ConverterPAC or an airblock. If the slot is left empty, it
will provide an airflow escape, significantly degrade thermal performance and can cause failure.
ConverterPAC Feature Summary
ConverterPAC OVP OCP OTP RS LS PG TrimPot
ModuPAC™Std Std Std Std Opt Opt Opt
DualPAC™N/A Std N/A Std Opt N/A Opt
JuniorPAC™N/A Std N/A Std Opt Opt Opt
RamPAC™N/A Std N/A Std Opt Opt Opt
OVP Overvoltage Protection (latching) OCP Overcurrent Protection (auto-recovery)
OTP Overtemperature Limiting (latching) RS Remote Sense
PG Power Good (DC OK) LS Local Sense
Installing ConverterPACs as Drivers
ConverterPACs can be installed in empty slots by simply sliding in the new ConverterPAC and securing
the screw at the base. Power and interface connections can be made after the ConverterPAC has
been installed.
Installing Booster ModuPACs to Increase Output Power
ConverterPACs can be paralleled for more power. Additional power to an output is obtained by
connecting one or more Boosters in parallel with a single driver. The driver can be placed in any open
slot. All Boosters should be inserted in the slots to the immediate right of the driver as viewed from
the output end of the MegaPAC. Figure 2 shows a Driver placed in slot #1 and three Boosters placed
in slot numbers 2 – 4. After inserting the Driver and Boosters, they are paralleled using bus bars across
the positive and negative output studs. Drivers should not be paralleled with each other. For help in
identifying Boosters and Drivers, refer to the section on MegaPAC Part Numbers.
Figure 2
Paralleling ConverterPACs
Bus Bars for Paralleling
Loosen screw to
remove ConverterPAC
Driver
Boosters
12345678

UG:123 Page 7
ConverterPAC™ Output and Connector Location
and Connector Pin Identification
DC MegaPAC™ Mechanical Drawings
ModuPAC
JuniorPAC
RamPAC
DualPAC
1
2
3
4
J3
1 VCC
2 Power Good
3 Power Good Inverted
4 Signal Ground
Pin
DC OK (Power Good)
1&4 +VOUT
2&5 –VOUT
3 +Sense
6 –Sense
DualPAC Output Connector
Pin
J1A & J1B
1
2
3
4
5
6
Molex #39-01-043 housing
using #39-00-0031 terminals
and 22-28AWG stranded wire.
Use Molex tool #57005-5000.
Molex #39-01-2060 housing
with #39-00-0039 terminals and
18-24AWG stranded wire. Use
Molex tool #11-01-0197.
Molex #50-57-9403 housing,
using #16-02-0103 terminals and
22-24AWG stranded wire. Use
Molex tool #11-01-0208.
1
2
3
Sense Connector
1 Trim Pin Access
2 +Sense
3 –Sense
Pin
J2
–VOUT
+VOUT
DC
+
DC
–
.45 [11,4mm]
5.10
[129,5mm]
6.75 [171,4mm]
11.68 [296,7mm]
CONNECTIONS J9
INPUT POWER
SIGNALS J10
STATUS/CONTROL
OUTPUT
OUTPUT
NORMAL
AIR FLOW
2.92
[74,2mm] RETURN
.62
[15,7mm]
6.04 [153,4mm]
3.38
[85,6mm]
4 MOUNTING HOLES EACH SURFACE
(M4/#8-32, .15 [3,8mm] MAX. PENETRATION)
TOP
.22
[5,6mm]
1.0
[25,4mm] 1.85
[47mm]
WESTCOR
MegaPAC
DC
SIDE VIEW
TOP VIEW
FRONT VIEW
DO NOT LOOSEN OR
TIGHTEN INNER NUTS
#4-40 CAPTIVE SCREWS
TO SECURE/REMOVE
CONVERTERPACS,
8 PLACES
1/4 - 20 ZINC PLATED
STEEL, SERRATED
FLANGED NUTS
45LB/IN MAX.
11.37 [288,8mm]
Amp 25 pin connector #746862-2
plug for flat ribbon cable. Mates with
housing Amp #747548-2 plus slide
latch or similar.
234567
18910 11 12 13
14 15 16 17 18 19 20 21 22 23 24 25

UG:123 Page 8
Part Numbering
DC MegaPAC™ MDxA-xCxBxxx
e.g., MD2-N8103
xA= number of outputs
xB= number of modules
xxx = assigned by Northwest Power, Inc.
xC= DC input voltage range
0= 12VDC input (10 – 20V range)
1= 24VDC input (21 – 32V range)
W= 24VDC input (18 – 36V range)
2= 36VDC input (21 – 56V range)
3= 48VDC input (42 – 60V range)
N= 48VDC input (36 – 76V range)
4= 72VDC input (55 – 100V range)
ConverterPAC™ xCXxDV/xEAxF
e.g., 3M15V/10A
e.g., NM15V/10ADFIL
e.g., D15V/6.7A-12V/8.3AT
X= ConverterPAC type
M= ModuPAC™D= DualPAC™J= JuniorPAC™R= RamPAC™
B= BatPAC™L= QPAC (VI-200) U= UniPAC™
XL = QPAC™(VI-200) LD = DualQPAC™(VI-J00)
xC= DC input voltage range (only used for DC MegaPAC ConverterPACs)
0= 12VDC input (10 – 20V range)
1= 24VDC input (21 – 32V range)
W= 24VDC input (18 – 36V range)
2= 36VDC input (21 – 56V range)
3= 48VDC input (42 – 60V range)
N= 48VDC input (36 – 76V range)
4= 72VDC input (55 – 100V range)
xD= Voltage out
xE= Current out (rounded to 1 decimal point)
xF= Options (See below*). Can be multiple options.
*ConverterPAC options
BBooster module MM-Grade module
DDC OK or Power Good (N/A on DualPAC) RRAM external
FFull 50 – 110% output adjustment STrimpot removed for external BatPAC adjustment
F1 50 – 107.5% output adjustment T90 – 110% output adjustment
F2 50 – 105% output adjustment T1 90 – 107.5% output adjustment
F3 50 – 102.5% output adjustment T2 90 – 105% output adjustment
F4 50 – 100% output adjustment T3 90 – 102.5% output adjustment
F5 60 – 110% output adjustment T4 90 – 100% output adjustment
F6 70 – 110% output adjustment T5 98 – 105% output adjustment
F7 80 – 110% output adjustment T6 100 – 110% output adjustment
F8 90 – 110% output adjustment V1 "VXI" low noise (150mV or less) for 24V outputs
F9 100 – 110% output adjustment V2 "VXI" low noise (50mV or less) for outputs < 24V
IIndustrial Grade module V3 1% ripple for outputs >24V
KCustom SRF module used ZOther special feature
LLocal sense

UG:123 Page 9
DC MegaPAC™ Quick Install Instructions
Mounting the DC MegaPAC
 The DC MegaPAC can be mounted on any of four sides.
 Use #8-32 or M4 mounting screws. Maximum penetration should
not exceed 0.15in [3,8mm].
 Maintain 2in [5,1cm] clearance at either end for airflow.
Output Connections
Power Connections
Installing ring lugs and/or bus bars on output studs:
 The upper stud is Positive and the lower stud is the Return.
 Remove outer nut. Do not remove or loosen inner nut.
 Place ring lug over output stud.
 Replace and tighten outer nut to a maximum torque of 45lb.in. Do Not Over-Tighten Nuts.
Installing power connectors on DualPACs (J1A and J1B):
 Use Molex mating receptacle #39-01-2060 with #39-00-0039 terminals provided.
 Pins 1 and 4 are Positive, while pins 2 and 5 are the Return.
 Attach terminals to 18 - 24AWG stranded wire using Molex tool #11-01-0197.
Sense Connections
Sense connections must always be made. Failure to connect Sense lines can cause
failure to the unit.
Sense Connector J2:
Sense connections do not have to be made if the Local Sense option has been ordered.
(An “L” in the ConverterPAC™part number means the Local Sense option has been
installed; e.g., M5V/40AL.)
Use Molex mating receptacle #50-57-9403 with #16-02-0103 terminals provided.
 J2-2 is the +Sense and J2-3 is the –Sense.
 Attach terminals to 22 - 24AWG twisted pair wire using Molex tool #11-01-0208.
 Attach opposite ends of Sense lines to point where regulation is desired.
 Verify that Sense lines are not cross-connected before applying input power.
Sense Connections on DualPACs:
 Sense connections do not have to be made if the Local Sense option has been ordered. (An “L” in the
ConverterPAC part number means the Local Sense option has been installed;
e.g., D5V/20AL-12V/4.2AL.)
 Sense connections are available on the J2 connector or the J1A and J1B connectors.
Either can be used.
 If using J2 connector, see instructions above for “Sense Connector J2.”
 Pin 3 is the +Sense and Pin 6 is the –Sense.
 Attach terminals to 18 - 24AWG twisted pair wire using Molex tool #11-01-0197.
 Verify that Sense lines are not cross-connected before applying input power.
DualPAC™Output Connector
Sense Connector
DualPAC Output Connector
1&4 +VOUT
2&5 –VOUT
3 +Sense
6 –Sense
Pin
J1A & J1B
1
2
3
4
5
6
1
2
3
1 Trim Pin Acces
s
2 +Sense
3 –Sense
Pin
J2
1&4 +VOUT
2&5 –VOUT
3 +Sense
6 –Sense
Pin
J1A & J1B
1
2
3
4
5
6

UG:123 Page 10
Trim Pin Connection J2
 The Trim J2 connection should only be made if the trim option has not been installed.
(A “T” or an “F” in the ConverterPAC™part number means the trim option is installed;
e.g., M5V/40AT).
 Use Molex mating receptacle #50-57-9403 with #16-02-0103 terminals provided.
 J2-1 provides trim access.
DC OK (Power Good) Connection J3
 DC OK is only available as an option and is not always present.
 J3-4 is VCC IN, J3-3 is Power Good, J3-2 is Power Good inverted,
and J3-1 is Signal Ground.
 Use Molex mating receptacle #39-01-0043 with #39-00-0031 terminals provided.
 Attach terminals to 22 – 28AWG stranded wire using Molex tool #57005-5000.
Input Connections
Input Power J9
 Input DC power is applied to solderless lugs on J9 using 2AWG wire.
 Maximum torque is 25lb.in.
 A fuse or circuit breaker is recommended in the input line.
Interface Connections J10
 Use 25-pin D-sub connector provided.
 J10-8 to 11 and J10-21 to 24 are Enable/Disable for slots 1 – 8.
 J10-16, 17 are VCC, J10-12 and 15 are Signal Ground, J10-18 is AC Power OK,
and J10-5 is General Shutdown.
DC OK (Power Good)
4
3
2
1
J3
J3-4 VCC
J3-3 Power Good
J3-2 Power Good Inverted
J3-1 Signal Ground
Pin
Input Connections J9
Sense Connector
1
2
3
1 Trim Pin Acces
s
2 +Sense
3 –Sense
Pin
J2
J10 INTERFACE CONNECTOR IDENTIFICATION
1 Signal Ground 14 No Connection
2 Signal Ground 15 Signal Ground
3 Overtemp. Warning 16 VCC +5 volt, 300mA
4 Analog Temperature 17 VCC +5 volt, 300mA
5 General Shutdown 18 Input Power OK
6 No Connection19 Input Power Fail
7 No Connection20 No Connection
8 Enable/Disable #8 21 Enable/Disable #7
9 Enable/Disable #6 22 Enable/Disable #5
10 Enable/Disable #4 23 Enable/Disable #3
11 Enable/Disable #2 24 Enable/Disable #1
12 Signal Ground 25 Gate Out Slot #8
13 Gate In Slot #1
Amp 25-pin connector #746862-2
plug for flat ribbon cable. Mates with
housing Amp #747548-2 plus slide
latch or similar.
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J10

UG:123 Page 11
Interface Connections
Chassis Input Power Terminals (J9)
Input DC power is applied to solderless lugs J9, using a wire size of 2AWG. J9-1 is the +DC Voltage
IN connection, and J9-3 is the –DC Voltage IN connection. The Earth Ground is accessed via J9-2, a
size 10-32 self-locking PEM nut. Maximum torque recommended is 25lb.in. A fault clearing device,
such as a fuse or circuit breaker at the power supply input is strongly recommended. For an output
of 1600 watts with operation on 48VDC (and low line operation of 42 volts), a fast-blow fuse of 50
amps is recommended. Start up inrush current is limited by a thermistor and in most cases will be less
than nominal line current during operation. Start up inrush current can be calculated by I = MaxVIN/10
(where Max VIN is the high line operating voltage. See Table 1). Example: for a nominal 48V input, the
maximum operating voltage is 76; therefore, I = 76V/10 = 7.6 amps.
Note: A fault clearing device, such as a fuse or circuit breaker at the power supply input is required per safety agency
conditions of acceptability.
Output Power Connections (+P, –P for Single Output, or J1A/J1B for Dual Outputs)
For single output ConverterPACs™, these terminals are two 1/4 - 20 plated steel studs. The upper
stud is positive with respect to the lower stud. For dual output ConverterPACs, there is a six-pin Molex
connector for each output. J1A pins 1 and 4 are the +Output, and J1A pins 2 and 5 are the –Output.
Pins 3 and 6 are duplicates of the Remote Sense terminals present on J2A and J2B. Use appropriate
wire size rated to handle the full output current, including short circuit levels. Avoid large current loops
in output cables; run power and return cables next to one another to minimize inductive effects. All
outputs are isolated and can provide positive or negative outputs.
Output +/–Sense Connections (J2 for Single Output, or J2A/J2B for Dual Outputs)
Although all outputs are open-Sense protected, the +/–Sense terminals MUST be connected to their
respective outputs before the DC MegaPAC™is powered up. Regardless of the output polarity
configured, the +Sense should always connect to the +Power output. The –Sense connects to the
–Power output. Sense connections are not required on booster ConverterPACs™, BatPACs™, or if the
Local Sense option is specified. Sense pins can be accessed on J1A/J1B or J2A/J2B on dual output units.
Signal Ground (J10-1, 2, 12, 15)
Signal Ground (Connector Pin Identification on Page 11) is an isolated ground reference for all J10
interfacing signals, and can be used for ConverterPAC output status signals such as Power Good. This is
not the same as Earth Ground on input power connector J9.
Figure 3
Input Panel Connectors
DC
+
DC
–

UG:123 Page 12
Enable/Disable (J10-8 to J10-11, and J10-21 through 24)
The Enable/Disable control pins allow ConverterPAC™outputs to be sequenced either on or off. For the
DC MegaPAC™, J10-8 through 11 and J10-21 through 24 are the control pins for output positions 1
through 8. For DualPACs™, both outputs are sequenced. In parallel arrays, only the driver ConverterPAC
need be controlled. The Enable/Disable pins should be pulled low to less than 0.7V with respect to
Signal Ground to disable the outputs. They will sink 10mA maximum. These pins should be open
circuited or allowed to exceed 4.5V when enabled. Do not apply more than 6V to these inputs at any
time. If driven from an electromechanical switch or relay, a capacitor should be connected to eliminate
the effects of switch bounce.
General Shutdown /GSD (J10-5)
The GSD control pin on J10-5 allows simultaneous shutdown of all ConverterPAC outputs (see Figure 4).
This pin must be pulled down to less than 0.7V, and will sink 10mA maximum to shut down all outputs.
The GSD pin should be open circuited or allowed to exceed 4.5V when not in use, or when the outputs
are to be enabled. Do not apply more than 6V to this input at any time. Normal open circuit voltage is
1.5 – 3V with respect to Signal Ground. If driven from an electromechanical switch or relay, a capacitor
should be connected to eliminate the effects of switch bounce.
J10 INTERFACE CONNECTOR IDENTIFICATION
1 Signal Ground 14 No Connection
2 Signal Ground 15 Signal Ground
3 Overtemp. Warning 16 VCC +5 volt, 300mA
4 Analog Temperature 17 VCC +5 volt, 300mA
5 General Shutdown 18 Input Power OK
6 No Connection19 Input Power Fail
7 No Connection20 No Connection
8 Enable/Disable #8 21 Enable/Disable #7
9 Enable/Disable #6 22 Enable/Disable #5
10 Enable/Disable #4 23 Enable/Disable #3
11 Enable/Disable #2 24 Enable/Disable #1
12 Signal Ground 25 Gate Out Slot #8
13 Gate In Slot #1
Amp 25-pin connector #746862-2
plug for flat ribbon cable. Mates with
housing Amp #747548-2 plus slide
latch or similar.
234567
18910 11 12 13
14 15 16 17 18 19 20 21 22 23 24 25
J10
Figure 4
Interface Connector
DC MegaPAC
24
1
5
Signal Ground
General Shutdown
Enable/Disable Output 1
J10
1
0
TTL "1" (OFF)
TTL "0" (ON)
A TTL "1" applied to the base of the transistor turns
output OFF. Pin 1 (or Pin 12 for GSD) is pulled Low
with respect to Signal Ground. 16 VCC
Enable/Disable Control
Figure 5
Enable/Disable and
General Shutdown

UG:123 Page 13
Input Power OK (J10-18)
This is an active high TTL compatible signal and provides a status indication of the DC input power
(see Table 1 and Connector Pin Identification on Page 11). It is capable of sinking 20mA maximum. This
signal switches to a TTL “1” when VIN is within its specified range.
Operating Range Power OK Trigger
Code Nominal VDC Low LIne High LIne Low LIne
Cut Off
High LIne
Cut Off
0 12 Volts 10 Volts 20 Volts 6V – 10V 20V – 23V
1 24 Volts 21 Volts 32 Volts 16V – 21V 32V – 36V
W 24 Volts 18 Volts 36 Volts 12V – 18V 36V – 41V
2 36 Volts 21 Volts 56 Volts 11V – 21V 56V – 63V
3 48 Volts 42 Volts 60 Volts 34V – 42V 60V – 68V
N 48 Volts 36 Volts 76 Volts 23V – 36V 76V – 86V
4 72 Volts 55 Volts 100 Volts 40V – 55V 100V – 111V*
*Do not apply greater than 100 Volts to the input of the DC MegaPAC™.
Input Power Fail (J10-19)
The Input Power Fail signal on pin J10-19 is the inverse of the Input Power OK signal on J10-18, and
goes to a TTL "0" when the input DC power is OK. It is capable of sinking 20mA maximum.
Overtemperature Warning (J10-3)
J10-3 is a signal that asserts a TTL level "1" if the air temperature exceeds the following factory set
levels. The warning trip point is 65 – 76°C, typically, and recovery point is 60 – 71°C, typically.
Overtemperature Shutdown
If the inlet ambient air temperature exceeds the following factory set levels, the outputs are disabled.
The shutdown trip point is 70 – 81°C, typically, and recovery point is 40 – 48°C, typically.
Analog Temperature Monitor (10-4)
This signal on J10-4, referenced to Signal Ground, provides an analog DC voltage output between
0 and 10V that represents the air temperature of 0 – 100°C, respectively, inside the power supply. The
inlet air temperataure is monitored close to the fan.
Gate IN/Gate OUT (J10-13, 25)
This signal on J10-4, referenced to Signal Ground, provides an analog DC voltage output between
0V and 10V that represents the air temperature of 0 – 100°C inside the power supply. The inlet air
temperature is monitored close to the fan.
The driver DC MegaPAC (ModuPAC, slot #8) generates the Gate OUT signal and sends it to the booster
DC MegaPAC (ModuPAC, slot #1). The Vicor zero-current switching booster technology provides for
accurate, dynamic power sharing within arrays, without the need for trimming, module "matching" or
external components.
Table 1
Input Voltage Range
& Power OK Limits

UG:123 Page 14
Auxiliary VCC +5V/0.3A (J10-16, 17)
The VCC on J10-16 and J10-17 is an auxiliary 5V regulated power source (see Figure 6 and Connector
Pin Identification on Page 11). It is +5VDC (±5%) with respect to Signal Ground, and can supply 300mA
maximum. It is short-circuit proof, but if shorted, all outputs will shut down through the
Enable/Disable circuitry. The Auxiliary VCC typically powers user circuitry or is used with the Power
Good circuitry to provide a pull-up reference for the outputs of the DC Power Good circuit on a
ModuPAC™. If used for this purpose, a Signal Ground on J10 must also be connected to the J3-1 Signal
Ground pin of the ModuPAC.
Power Good (J3-3)
The optional Power Good signal on J3-3 is referenced to Signal Ground on J3-1, and indicates the
status of the output voltage. This signal is asserted a TTL “1” when the output voltage is above 95% of
nominal. It is a TTL “0” when the output voltage is below 85% of nominal.
If the Trim option is also used, the Power Good trip points DO NOT track with the trimmed voltage. It
is possible to trim the output below the fixed setpoints of the Power Good circuit and cause a negative
Power Good signal.
Power Good Inverted (J3-2)
This is the inverse of the Power Good signal and is referenced to Signal Ground on J3-1.
Figure 6
Auxiliary VCC
Figure 7
Power Good and VCC
78M05 Auxiliary VCC
16
0.1µF
Signal Ground
J10
15
+5V/300mA
Auxiliary VCC
17
Signal Ground
3
VCC
1
J3
10kΩ
2.49kΩ
2N2222
2.49kΩ
4
Power Good
2
Power Good
ConverterPAC

UG:123 Page 15
Signal Ground (J3-1)
Signal Ground on J3-1 is an isolated secondary ground reference for J3 status signals. It is used to
provide a reference point for the Power Good circuitry and is not the same as Earth Ground on input
power connector J9.
VCC In (J3-4)
The VCC In on J3-4 is an input that requires +5V either from the J10 Auxiliary VCC, or from another
source. Input current to this pin is limited by an internal resistor to 3mA. If the J10 Auxiliary VCC
is connected to VCC In on J3- 4, then at least one J10 Signal Ground must be connected to Signal
Ground on J3-1.
+Sense/–Sense (J2-2 and J2-3)
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 0.5V (0.25V per lead) can be obtained. Use
twisted pair 22 – 24AWG 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.
External Trim (J2-1)
Output voltage can be trimmed using an optional factory-installed Trim potentiometer or with the Trim
pin (see Figure 9). 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.
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, 3.3, 5, 12, 15, 24, 28, and 48V. If using a nonstandard voltage, or if a ConverterPAC is ordered
with a Trim option, the resistor calculations will differ from those below. Please consult the factory
for assistance.
Figure 8
Sense Leads
(Remote Sense)
Load
(Local Sense)
+P +OUT
J2-2 +Sense
J2-3 –Sense
–P –OUT
Use 22-24AWG Twisted Pair Wires

UG:123 Page 16
Output Module VREF RTH
VI-200/VI-J00 ≥3.3V 2.50V 10.0kΩ
VI-200/VI-J00 <3.3V 0.97V 3.88kΩ
Example:
±10% Trim adjust on a 12V nominal output.
Figure 9 shows a typical variable Trim circuit. Using a 10kΩtrimpot (R7), the resistor values for R6 and
R8 can be calculated as follows:
V1= VREF + 10% = 2.75V Given: VREF = 2.5V (see Table above)
IR5 = (2.75V – VREF)/RTH = (2.75V - 2.5V) / 10kΩ= 25µA
Setting the bottom limit:
VR6 = 2.5V – 10% = 2.25V
And since IR5 = IR6 = 25µA,
R6 = VR6 / IR6= 2.25V / 25µA = 90kΩ
V2= V1+ VR6 = 2.75V + 2.25V = 5V
IR7 = V2/ R7 = 5V / 10kΩ= 500µA
IR8 = IR7 + IR6 = 525µA
VR8 = (VNOM + 10%) – V2= 13.2V – 5V = 8.2V Given: VNOM = 12V
R8= VR8 / IR8 = 8.2V / 525µA = 15.62kΩ
Using the above resistor combination, a 12V output can be trimmed externally up to 13.2V and down to
10.8V. For further information on external trimming, refer to Chapter 5 of the Applications Manual or
consult the factory for assistance.
CONSULT APPLICATIONS ENGINEERING WHEN TRIMMING OUTPUTS BELOW 5V.
Figure 9
External Trim
(Remote Sense)
Load
+P +OUT
J2-2 +Sense
J2-3 –Sense
–P –OUT
Use 22-24AWG Twisted Pair Wires
R5
V
REF
J2-1
R6
R8
R7
To Error
Amplifier
R4
R3
R2
R1
+
+
V2
V1
-
-
R
TH
Use 22-24AWG
Twisted Pair Wires

UG:123 Page 17
Specifications
Input Characterisitcs
Input Voltage 12VDC (10 – 20), 24VDC (18 – 36), 36VDC (21 – 56), 48VDC (36 – 76),
72VDC (55 – 100)
Power Factor 1.0
Line Regulation 0.2% max. from 10% to full load
Inrush Current 5A peak @ 48VDC input
Conducted EMI BTR 2511, Issue 4
Transient Surge EN/IEC 1000-4-2 Level 4
Output Characterisitcs
Load Regulation 0.2% max. from 10% to 100% load;
0.5% max. from 0% to 10% load
Setpoint Accuracy 1% for standard voltages;
2% for special or adjustable voltages
Ripple and Noise
Std. outputs: 2% or 100mVP-P max., whichever is greater, 10% min. load
VXI options ( <24V outputs): 50mVP-P max for outputs <15VDC;
150mVP-P max. for 24VDC outputs;
QPAC™, DualQPAC™, JuniorPAC™, RamPAC™: <10mVP-P max.
Overcurrent Protection
105 – 130% > 5V outputs & DualPACs, JuniorPACs, RamPACs, DualQPACS,
JuniorQPACs™;
30 – 125% < 5V outputs
Overvoltage Protection
ModuPACs and QPACs: 115 – 135%;
N/A to DualPACs, JuniorPACs, BatPACs™, RamPACs, DualQPACs and Ju-
niorQPACs
Efficiency 83% typical
Output Power 1600W @ 45°C (Output power dependent upon Input voltage)
Environmental Characteristics
Storage Temperature –40°C to +65°C
Operating Temperature
C-grade: 0°C to +45°C full power, 0°C to +65°C half power
I-grade: –20°C to +45°C, –20°C to +65°C half power
See temperature derating curves
Safety Approvals UL 1950 (2nd), CSA C22.2 No. 234, IEC 950, EN 60 950
Product Weights 9.25lbs (4,2kg) fully configured
0.7lbs (0,32kg) ConverterPAC™
Warranty 1 year
See vicorpower.com for complete warranty statement.
Humidity 0 – 95% noncondensing
Altitude 15,000 feet maximum. Derates linearly.

UG:123 Page 18
Temperature Derating
Figure 10
Temperature Derating for
MegaPACs™ using 5V Current
Generation ConverterPACs™
(See Curves Below for Non 5V
ConverterPAC Configurations)
Figure 11
Temperature Derating for
MegaPACs using 5V Current
Generation ConverterPACs
(See Curves Above for 5V
ConverterPAC Configurations)

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Information in this document is believed to be accurate and reliable. HOWEVER, THIS INFORMATION
IS PROVIDED “AS IS” AND WITHOUT ANY WARRANTIES, EXPRESSED OR IMPLIED, AS TO THE
ACCURACY OR COMPLETENESS OF SUCH INFORMATION. VICOR SHALL HAVE NO LIABILITY FOR THE
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LIMITATION, LOST PROFITS OR SAVINGS, BUSINESS INTERRUPTION, COSTS RELATED TO THE REMOVAL
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Vicor reserves the right to make changes to information published in this document, at any time
and without notice. You should verify that this document and information is current. This document
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All guidance and content herein are for illustrative purposes only. Vicor makes no representation or
warranty that the products and/or services described herein will be suitable for the specified use without
further testing or modification. You are responsible for the design and operation of your applications
and products using Vicor products, and Vicor accepts no liability for any assistance with applications or
customer product design. It is your sole responsibility to determine whether the Vicor product is suitable
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11/17
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