USER GUIDE | UG:003
PRM
®
and VTM
®
Customer Evaluation Boards
The Customer Evaluation Boards described in this document are intended to acquaint you with the
TM
benefits and features of a Factorized Power Architecture (FPA ). They are not designed to be installed
in end-use equipment.
Contents
Introduction
Board Overview
Recommended
Hardware
Initial Set Up
Baseline Test
Procedure
VTM-CB
Page
1
2
3
Please read this document before setting up a Customer Evaluation
Board.
During operation, the power devices and surrounding structures can be operated safely at high temperatures.
• Remove power and use caution when connecting and disconnecting test probes and interface
lines to avoid inadvertent short circuits and contact with hot surfaces.
• When testing electronic products always use approved safety glasses. Follow good laboratory
practice and procedures.
4
4
Introduction
7
A Factorized Power Architecture offers a fundamentally new and improved approach to distributed
power. Factorizing DC-DC power conversion into its basic functions – isolation and transformation on the
one hand and output voltage control and regulation on the other – and arranging those functions in a
sequence maximizes power system performance and cost effectiveness. VTM modules put isolated current
multiplication and voltage division directly at the Point of Load (POL), and an upstream PRM
non-isolated regulator controls the Factorized Bus voltage supplied to the VTM to provide line and load
regulation. With this architecture, the Factorized Bus voltage can be relatively high; distribution losses can
be minimized with narrower copper traces; and the PRM may be located at any convenient location, either
adjacent to or remote from the VTM. PRMs operate from a wide variety of input sources to drive VTMs.
VTMs are extremely fast and quiet and provide voltage division ratios as high as 32. VTMs enable the user
to efficiently supply up to 100 A from each full VI Chip package at regulated output voltages as low as 0.8
Vdc or higher, as needed.
With FPA, only a VTM is needed at the POL. VTMs, unimpeded by serial inductance, feature very high
bandwidth and extremely fast transient response, allowing energy to be stored efficiently at the relatively
high Factorized Bus voltage. Without bulk capacitors at the POL, precious board real estate may be
reclaimed for essential functions. The density, efficiency, performance, cost-effectiveness, and architectural
superiority of FPA make it the least intrusive form of distributed power and facilitate the development of
more advanced, competitive products.
The PRM may be used as a standalone non-isolated regulation stage, whereas the VTM is intended to be
used with a PRM. For customers to evaluate these components, special Customer Boards are available. To
obtain one of these boards, simply append the chosen PRM or VTM part number with "-CB".
The DC-DC
8
Converter Chip Set
Ordering
Information
9
UG:003
vicorpower.com
Applications Engineering: 800 927.9474
Page 1
Please take a closer look at the PRM-CB board.
Figure 1 is a picture of a PRM-AL mounted to the PRM-CB board.
The board has several features that enable the user to fully explore the capabilities of the PRM-AL:
2
3
4
5
6
Figure 1
PRM-AL mounted
to PRM-CB board
1
7
8
9
Board Overview
(reference the designators in the image above)
1
2
3
4
5
Source voltage input points are designed to accommodate #10 hardware and Panduit ring lugs.
BE CERTAIN THAT THE POLARITY IS CORRECT BEFORE APPLYING POWER.
Auxiliary control (H01) - access points for PR, IL, TM, PC, and VH, (header shown installed).
Reference test point Signal Ground (SG).
Adjustment potentiometers for indicated function are used in conjunction with actuation of
corresponding switch in Item 5.
PRM port connections (switch bank and silk screen reference).
a. Toggling the switch indicated PC to the ON position inhibits the PRM output.
b. Toggling the switch indicated IL to the ON position enables an adjustable current limit effected
by varying the corresponding IL trim pot (Item 4).
c. Toggling the switch indicated SC to the ON position enables adjustment of the output voltage
down from the set point determined by the OS resistor by varying the corresponding SC trim
pot (Item 4). - CAUTION: depending upon the initial output voltage set point determined by
the OS resistor it is possible to trim the SC so low that the output shuts off. The minimum
output voltage per the data sheet is 26 Vdc.
d. Toggling the switch indicated CD to the ON position places the PRM in Adaptive Loop
regulation mode (for use with the VTM-CB) from the Local Loop regulation mode. (In Local
Loop mode the set voltage is regulated at the output terminals of the PRM.) Adjusting the
corresponding CD trim pot (Item 4) changes the gain of the loop to compensate for different
OS settings and/or interconnect resistive losses.
e. Toggling the switch indicated OSV (OS Variable) to the ON position requires the switch
indicated OSF (OS Fixed) be placed in the OFF position and allows the PRM output set point to
be varied within the range specified on the data sheet.
f. Toggling the switch indicated OSF to the ON position sets the output of the PRM to the
nominal value indicated on the data sheet. If this switch is in the OFF position and the OSV
switch is also OFF, the unit will not function.
g. IT IS BEST TO SET THE SWITCH POSITION AND CORRESPONDING TRIM POT SETTINGS
BEFORE APPLYING POWER TO THE BOARD.
UG:003
vicorpower.com
Applications Engineering: 800 927.9474
Page 2
6
7
8
Test point for Secondary Control (SC)
Output voltage points are designed to accommodate #10 hardware and Panduit ring lugs.
Output connector (J01) for mating with VTM-CB providing Vout and VC. As shown on the
schematic (Figure 2) there are four pins dedicated to the + Out, four for the -Out, and two for the
VC. Each contact is rated for 3 A. The excess capacity afforded by these pins can facilitate
testing multiple VTM-CBs from a single PRM-CB using an appropriate wiring harness and mating
connector. This may also be achieved using the large pads of Item 7.
Output scope jack (J02). Headers H01 and J01 are 0.100" spacing, 10 position female,
manufactured by Sullins Electronics and available from Digi-Key as part # S5519-ND.
9
Below is the schematic for this PCB. Double clicking the image will launch Adobe Acrobat to
allow you a better view.
Figure 2
PRM-CB schematic diagram
Recommended Hardware
QTY
4
Description
ring lug
Manufacturer P/N
Panduit LCAS6-10-L
Kit # 26647 contains:
4
4
4
4
#10-32 screw
#10 flat washer
#10 lock washer
#10 hex nut
All hardware is stainless steel except the ring lug.
Kit # 26647 is included with the Customer Evaluation Board.
UG:003
vicorpower.com
Applications Engineering: 800 927.9474
Page 3
Initial Set Up
To test the PRM
®
mounted to the board it is necessary to configure the switch bank (Item 5) as shown
on the silk screen in Figure 3. Placing the switch bank in this state connects a fixed resistor between
OS and SG of the PRM that sets the output voltage of the PRM to the nominal value indicated on its
respective data sheet.
Failure to configure the switch bank in this state prior to testing may result in improper
output or no output.
Baseline Test Procedure - PRM-CB
1.0
Recommended Equipment
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
(Refer to Figure 3)
DC power supply – 0-100 V; 500 W.
DC electronic load – pulse capable; 0-100 V; 100 A minimum.
DMM.
Oscilloscope.
Appropriately sized interconnect cables.
Fastening hardware.
Fan (if the PRM is to be operated for extended periods of time or at an elevated
ambient temperature we recommend the supplied heat sink be installed).
Safety glasses.
Data sheet for the requisite PRM.
Figure 3
PRM Customer Board Layout
switch bank
(Item 5)
switch reference
(silk screen)
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Applications Engineering: 800 927.9474
Page 4
2.0
Hook Up
2.1
2.2
2.3
2.4
2.5
2.6
Connect the power supply +Out lead to the +In terminal of the Customer
Evaluation Board.
Connect the power supply –Out lead to the –In terminal of the Customer
Evaluation Board.
A high quality, low-noise power supply should be connected to these locations
Connect a lead between the +Out of the Customer Evaluation Board and +In
of the load.
Connect a lead between the –Out of the Customer Evaluation Board and –In
of the load.
Connections to these locations should be with short heavy gauge leads.
3.0
4.0
Verify Connections
Test Sequence
4.1
4.2
4.3
4.4
4.5
4.6
4.7
Have the latest version of the PRM
®
data sheet in hand.
Assure that the DC supply is set to 0 Vdc prior to turning the unit on.
Confirm that the switch bank is configured as shown in the silk screen on the board.
Turn on the DC supply.
Make sure the DC load is set to constant current and at 0 A prior to turning
on the load.
Turn on the DC load.
Connect an oscilloscope to the test point provided to monitor output voltage. Many
types of scope probes may be directly connected to these points if the probe is
equipped with a removable plastic sheath. Be careful to avoid creating ground loops
when making measurements of this voltage and the input voltage. It is recommended
that the measurements be made separately. Shorting the -input and -output of the PRM
will defeat the PRM current limit feature as the current shunt is in this path.
Turn on a fan if desired.
Raise the DC input voltage to the nominal value indicated on the data sheet.
Verify no load operation by raising and lowering the input voltage through the entire
input voltage range. The output voltage should remain constant within the tolerance
indicated in the data sheet.
Re-establish the nominal input voltage.
Slowly increase the load current to full load while monitoring the output voltage. The
output voltage should remain within the limits specified in the appropriate PRM data
sheet.
Return the load current to 0 A and decrease the input voltage to low line.
Repeat step 4.12. Depending upon the supply used and the source impedance it may
be necessary to adjust the input voltage to keep the input to the PRM at low line.
Return the load current to 0 A and increase the input voltage to high line.
Repeat step 4.12.
4.8
4.9
4.10
4.11
4.12
4.13
4.14
4.15
4.16
5.0
6.0
You have now verified the functionality of the PRM over the entire line and load
operating range.
Deviating from Nominal Settings
This board has provisions, as described in the Board Overview section, to adjust the
configuration of the PRM about the nominal values. The data sheet for the PRM has equations
and curves for determining the required resistor values needed for specific conditions.
Applications requiring output voltages other than the nominal setting will need to have the
new value set via the trim pots and respective switches. Reference Items 4 and 5 of the Board
Overview and the schematic shown in Figure 2.
6.1
Adjust the PRM Output Voltage Set Point
6.1.1 Make sure that the power is removed from the unit prior to making adjustment.
6.1.2 Using a DMM (set to measure resistance), probe between SG (Item 3) and the pad
labeled OS located next to the 5 kΩ trim pot R08.
UG:003
vicorpower.com
Applications Engineering: 800 927.9474
Page 5
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