USER GUIDE | UG:019
NBM6123 ChiP™ Analog Low-Voltage
Non-Isolated Bus Converter Module Evaluation Board
Contents Page
Introduction 1
Contents 3
Features 3
Board Description
General Components
3
3
Test Points Description
5
Bill of Materials
8
Recommended
Test Equipment
9
Basic Connections
9
Board Operation Details
9
Thermal Considerations
10
Paralleling 10
Introduction
The Converter housed in a Package (ChiP) Non-Isolated Bus Converter Module (NBM) evaluation board
described in this document is designed to be used with the the through-hole NBM6123 ChiP family
(PNs: NBM6123T46C15A6T0R, NBM6123T60E12A7T0R).
The NBM evaluation board can be configured for various enabling and fault-monitoring schemes, as
well as to exercise various loading conditions depending on the application requirements. The evaluation
board can be used to evaluate NBMs in either a stand-alone configuration or as an array of modules.
It is important to remember the fast response of NBMs can readily show the limitations of the source,
load and associated wiring connected to the evaluation board. Care should be exercised to minimize the
stray source and load impedance in order to fully exercise the NBM.
The NBM non-isolated topology allows start up in forward and reverse directions and provides
bidirectional protections. However, if powertrain is disabled by any protection, and VSEC is present, then
voltage equal to VSEC minus two diode drops will appear on the primary side.
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IMPORTANT NOTICE:
Read the precautions below entirely BEFORE using the NBM™ evaluation board. Do not
operate the evaluation board unless you have the appropriate safety precautions in place on
your bench to guarantee safety.
The list below is not comprehensive and is not a substitute for common sense and good practice.
nn
During operation, the power devices and surrounding structures can be operated safely
at high temperatures.
nn
Remove power and use caution when connecting and disconnecting test probes and interface lines to
avoid inadvertent short circuits and contact with hot surfaces.
nn
Never use a jumper in place of the fuse.
nn
When testing electronic products always use approved safety glasses.
Follow good laboratory practice and procedures.
nn
Avoid creating ground loops between the SGND and PGND pins when making measurements.
nn
Care should be taken to protect the user from accidental contact when under power.
nn
Care should be taken to avoid reversing polarities if connecting to the opposite
(solder) side of the board.
nn
The product evaluation boards described in this document are designed for general laboratory
evaluation and are not suitable for installation in end-user equipment.
nn
Refer to the specific NBM module data sheet for electrical, thermal and mechanical product details.
This board provides a convenient way to evaluate or demonstrate the performance of Vicor NBM
products. Kelvin connections are provided for accurate voltage measurements on power nodes. Sockets
are provided to permit quick installation and changing of bulk filtering capacitors. The evaluation
board also provides lugs for input / output connections, test points and sockets for easy connection to
standard test equipment, and a high-performance air-cooled heat-sink assembly.
Enable Options
1. Apply input voltage to the NBM primary or secondary pins greater than the
undervoltage lockout. (Default)
2. On-board mechanical switch.
3. External control using available test point.
Fault Monitor Options
1. On-board LED: the VAUX pin drives a visible LED for visual feedback on the
NBM status such as enabled or fault condition.
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Contents
The evaluation board ships with the following contents:
nn
1 x NBM™ evaluation board
nn
1 x Top heat sink pre-installed
nn
1 x hardware kit:
nn1 x through-hole aluminum electrolytic output capacitor (C121)
nn3 x Connector Receptacle 8 position
nn2 x Connector socket 2 position
nn5 x size 10 screws, lugs and washers
Features
The NBM evaluation board has the following features:
1. Input and output lugs for source and load connections
2. Appropriately rated input fuse
3. Input aluminum electrolytic capacitor for additional source decoupling
4. Basic output filtering footprint, including sockets to add through-hole output aluminum electrolytic
capacitors
5. Toggle switch for enabling and disabling the NBM via the enable (EN) pin
6. Oscilloscope probe jack for accurate, high frequency output voltage measurements
7. Connectors for NBM signal pins (TM, EN, and VAUX) and temperature monitor filtered signal
8. Kelvin voltage test points for all power pins
Board Description
The following section provides a detailed description of the evaluation board components, test
points and sockets.
General Components
1. (PS01): The NBM is inherently a reversible product. This means that a voltage source placed at
the secondary will bias the powertrain and allow the units to power up. Note if the units is held
in a disabled state using the EN pin any voltage applied to the secondary pins of NBM will appear
on the primary pins minus two diode drops. Loading the primary in this state may permanently
damage the unit since the load current path would be through the body diode of the primary stage
FETs . See the NBM data sheet for additional insight.
2. Input lugs: Sized for #10 hardware. Use for making connection to the input source. This board
does not contain reverse polarity protection. Check for proper polarity before applying the power.
It is important to remember that noise from the source and voltage drops, will appear at the output
of the bus converter multiplied by transformation ratio (K). The K factor is the ratio of the output
voltage to the input voltage (VOUT / VIN).
3. Input fuse (F101 & F102): Appropriately rated for the NBM model installed on the board. The fuse
is meant to protect against excessive damage in a short-circuit event.
4. Input filtering: aluminum electrolytic input capacitor (C101).
5. Enable / Disable switch (SW101): When actuator is towards “ON” text on the board, the (EN) pin
will be open and the NBM will be enabled. When actuator is towards “OFF” text on the board, the
(EN) pin will be connected to (SGND) pin and the NBM will be disabled. When switch (SW101) is
“ON”, an external voltage source can control the EN pin state.
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6. Signal connector (J102): provides access to the bus converter signal pins (TM, EN and VAUX) as
well as (TM_DC) externally filtered signal. All signal pins are reference to the primary non-isolated
voltage return (SGND) pin.
Figure 1
NBM™ signal connector (J102)
2
4
6
8
SGND
SGND
SGND
SGND
1
3
5
7
TM_PWM TM_DC
EN
VAUX
nnTemperature Monitor (TM): The NBM (TM) pin outputs a 250kHz PWM signal. A 1kΩ and
a 10nF is the recommended low-pass filtering solution. (TM_PWM) and filtered (TM_DC) are
both accessible on (J102) connector header. (TM_DC) measures 1.27V for a 27°C internal
temperature corresponding to a (TM_PWM) duty cycle of 38.48%
nnEnable Control (EN): Connecting the NBM (EN) pin to (SGND) will disable the module.
(SW101) can be used to turn off the powertrain and disable the module. The (EN) pin is
internally pulled up. During a fault condition, this signal and will remain high while input voltage
is applied and greater than VµC_ACTIVE. This connector can be used to bus the (EN) pin in an
array allowing array synchronous start up.
nnAuxiliary Voltage Source (VAUX): The NBM (VAUX) can be used as a fault flag it is internally
driven low during a fault condition. The (VAUX) pin can also be used as a ready to process
full power flag. A 2ms delay from powertrain active is introduced on this pin signaling the
end of soft start. During normal operation this pin can be used as an auxiliary supply up to
4mA max load.
7. Output lugs: Sized for #10 hardware. Use these lugs to connect the output directly to the load.
8. Output oscilloscope probe Jack (J101): Used for making accurate scope measurements of the
output voltage (e.g., ripple). The jack is directly compatible with many common passive voltage
probes models. Remove the grounding lead and insulating barrel of the probe and insert the
probe tip and barrel directly into the jack, insuring that the probe tip sits in the center socket of
the jack. To avoid the risk of an inadvertent short circuit, do not attempt to install while power is
applied. This Johnson Jack is Kelvin connected to the module output pins. The effect of the output
capacitors will not be noticeable.
9. Output filter: 10x output ceramic capacitors 1206 footprint provision (C103, C104 and
C113 – C120). In addition to socket (C121) that can be used for easy installation of an aluminum
electrolytic output capacitor included with in hardware kit of the evaluation board.
10. Chassis ground (R106): is a 2010 package. The footprint can be used to provide a convenient
means to short the chassis and heat sink common ground to the power-ground plane.
Figure 2
PCB#42142 evaluation board
photo, top side
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Test Points Description
Test nodes are labeled and include an SMT test point for attaching miniature probes, clips or hooks.
Table 1
Test point descriptions
Name
+VIN, PGND
EN, SGND
Description
Provide measurement test points for the input voltage of the NBM™ module.
Test points are Kelvin connected to the module input pins.
Used to measure the NBM EN pin relative to SGND pin.
TM_DC, SGND
Used to measure the filtered NBM TM signal using a recommended low pass
filter relative to SGND pin.
TM_PWM, SGND
Used to measure the NBM TM pin which is a pulse width modulated output
signal relative to SGND pin.
VAUX, SGND
Used to measure the NBM VAUX pin output signal relative to SGND pin.
+VOUT, PGND
Provide measurement test points for the output voltage of the NBM module.
Test points are Kelvin connected to the module output pins.
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UG:019
PGND
+IN
SGND
PGND
+IN
C102
29400-103
0603
0.01uF
TM_DC
37688
40A
FUSE
F102
42153
70A
FUSE
F101
SGND
1SW101
2
3
PGND
HS01
GND
LED
40058
0805
D101
1
3
5
7
2
4
6
8
DNP
R106
2010
DNP
DNP
CHASSIS_GND
C103
1uF
1206
25185-105
DNP
DNP
NBM
+OUT
C115
1uF
1206
25185-105
DNP
TP107
CHASSIS_GND
TP102
SGND
SGND
TP106
Kelvin
PS01
PGND
+VOUT
SGND
C104
1uF
1206
25185-105
DNP
C113
1uF
1206
25185-105
C114
1uF
1206
25185-105
DNP
C116
1uF
1206
25185-105
DNP
TP108
Kelvin
C117
1uF
1206
25185-105
DNP
C118
1uF
1206
25185-105
DNP
PGND
TP104
Kelvin
TP103
+IN
CL
VAUX
DA
EN
AD
TM
+VOUT
SER-IN
EN
SER-OUT
6123 LV Non-Isoloated BCM
TP101
TP105
TP111
TP110
TP109
+VIN
+VIN
0603
15462-0R00
0603
14695-00R0
R105
0603
15462-0R00
R104
R103
Kelvin
VAUX
TP115
TM_PWM
SGND
0603
14695-7500
750
R102
J102
EN
TP112
CONN HEADER R/A .100 8P
OS
A33079-ND / 5103166-2
41009
TM_PWM
TM_DC
EN
VAUX
SGND
C101
30799
CAP ALEL 10uF 20% 450V RAD
SW_GT11MSABE
40538
NBM ON/OFF CONTROL
0603
15462-1001
R101
1K
TM_PWM
TP114
EMI
TM_DC
TP113
PGND
1
C119
1uF
1206
25185-105
DNP
J101
33292
C120
1uF
1206
25185-105
DNP
H02
30799
C121
H01
DNP
PGND
+VOUT
PGND
+OUT
Figure 3
PCB#42142
evaluation board schematic
Page 6
Figure 4
PCB#42142 evaluation board,
top side
Figure 5
PCB#42142 evaluation board,
bottom side
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Bill of Materials
Following table describes the design specific components of the NBM™ evaluation boards.
Table 2
NBM evaluation board
components common
to all boards
Reference
Designator
Description
C101
CAP ALEL 10µ 20% 450V RAD
C102
CAP X7R 0.010µF 10% 50V 0603
D101
DLED RED 0805
ManuFacturer
Part Number
United Chemi-Con
EKXG451ELL100MK20S
Murata Manuafacturing GRM188R71H103KA01D
Rohm
F101
SML-211UTT86
Design specific – see Table 3
F102
Design specific – see Table 3
J101
JACK VERTICAL MECH THRU HOLE
J102
CONN HEADER R/A 0.100 8 POS 30 AU
Tektronix
131-5031-00
TE Connectivity Ltd
5-103166-2
HTSNK
Design specific – see Table 3
PCB Part Number
Design specific – see Table 3
R103
R104
R105
RES 0Ω JUMPER 1A 0603
KOA Speer Electronics
R102
RES 750Ω 1/10W 5% 0603
KOA Speer Electronics
RK73B1JTTD751J
R101
RES 1kΩ 1/10W 1% 0603
KOA Speer Electronics
RK73H1JTTD1001F
C&K Components
GT11MSABETR
ManuFacturer
ManuFacturer
Part Number
SW101
Table 3
BOM additions,
components which are NBM
model specific
ManuFacturer
SW Horizontal SPDT 1 POS SMD
Reference
Designator
Description
RK73Z1JTTD
Evaluation board numbers: NBM6123E60E12A7T0R; NBM6123E46C15A6T0R
PS01
PCB Part Number
F101
HTSNK
LV NBM
Vicor Corporation
NBM6123T60E12A7T0R;
NBM6123T46C15A6T0R
NBM evaluation board
Vicor Corporation
42142
Littelfuse
0TLS060.TXLS
Vicor Corporation
42676
FUSE 60A 170VDC THRU HOLE
BOM HEAT SINK, TOP
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Recommended Test Equipment
The following is a list of recommended test equipment.
1. Safety glasses.
2. DC power supply: Refer to the specific NBM™ model data sheet to ensure the supply has sufficient
power and current capability.
3. Electronic load: Refer to the specific NBM model data sheet to ensure the load has sufficient power
handling and current capability for testing.
4. Cooling fan.
5. Digital multi-meters (DMMs).
6. Oscilloscope and probes.
7. Interconnect wires, cables and fastening hardware.
Basic Connections
nn
Confirm bench equipment is powered off.
nn
Connect the input DC power supply positive lead to the +IN input lug of the evaluation board,
connect the input power supply negative lead to the PGND input lug of the evaluation board.
nn
Connect the CHASSIS_GND lug of the evaluation board to a safety “green wire” earth ground.
nn
Connect the +OUT lug of the evaluation board to the electronic load positive input, connect the
PGND output lug of the evaluation board to the electronic load negative input.
nn
Verify proper polarity of the connections.
nn
Verify (SW101) desired actuator position
nn
Direct airflow from the cooling fan through the NBM heat sink fins.
nn
Have the latest NBM datasheet on hand for reference.
Board Operation Details
nn
SW01 provides control over enable.
nnIn the “OFF” position, the switch will connect SGND pin to the EN net, which disables the NBM.
nnIn the “ON” position, the EN net is allowed to float.
nn
External connection to EN is permitted using the EN test point. (SW01) should be set to “ON” to
allow external control.
nn
The (J102) paralleling connectors can be used to connect EN nets across different boards.
Note: to enable the NBMs in a parallel array, all boards need (SW01) set to “ON” to avoid pulling the
EN node low.
nn
The heat sink assembly of the NBM is connected to the CHASSIS_GND lug.
A connection from the CHASSIS_GND lug to earth ground is required for safety as the heat sink will
be floating otherwise.
nn
The visible LED at D101 and its bias resistor network (R102 & R105) are connected to the VAUX pin.
LED turns “ON” when VAUX is high signaling that the NBM is ready to process full power.
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Thermal Considerations
The evaluation board is supplied with a pre-installed 27mm top only for PCB#42142. A fan blowing
across the evaluation board and heat sink assembly is required during operation at load. The fan
should be placed about 4 inches away from the evaluation board facing the output voltage side. A
typical bench-top fan is recommended providing about 1000LFM. Using the supplied rubber feet
is also required in order to elevate the board about 0.4 inches off a flat surface and enable air flow
underneath the PCB.
The PCB top layer used of the PCB#42142 is required to be of the same potential of the heat sink;
this is to allow heat transfer from the bottom of the ChiP™ and leads to the heat sink. Chromerics
GEL-8010 is used on both top and bottom surface of the ChiP. (Between the ChiP top and heat sink
as well as the ChiP bottom and the PCB). It is also required to apply to the heat sink extended surface
resting on the PCB.
Paralleling
The paralleling and sharing performance of multiple NBMs can be easily demonstrated by stacking
multiple evaluation boards and interconnecting the inputs and outputs with standoffs to create a
parallel array. Each NBM in an array operates in the same way as it does as a stand-alone unit. With
equal impedance, the load is effectively shared across multiple NBMs. Mismatches in this case are
modest, and are further canceled by an effective negative voltage vs. temperature coefficient.
The following connections and settings should be used for an array of NBM evaluation boards:
nn
All NBMs in a parallel array must be the same model.
nn
The boards should be physically stacked using metal standoffs at the +IN & PGND input lugs, the
+OUT & PGND lugs, and the CHASSIS_GND lug. This also connects these nodes electrically so that a
single source, single load and earth ground connection can be made to the system.
nn
The NBM is a three-terminal device; it is required to connect all PGND lugs to the same potential.
nn
Standoffs must be sufficient in length to avoid contact between boards and to permit airflow to all
NBMs in the system.
nn
If coordinated enable control then the paralleling connectors (J102) can be used to easily interconnect
the EN pin across boards.
nn
The paralleling connector receptacle (J102) is provided to daisy chain EN signal and SGND.
The receptacle will accept a wire size range 26 – 22AWG, 0.12 – 0.3mm2 wires.
The paralleling and current sharing capability of the devices can be demonstrated by stacking multiple
evaluation board and interconnecting the inputs, outputs and power grounds with standoffs of
sufficient current rating to create a parallel array. If synchronous start up is desired, connect EN pin 5
and SGND pin 6 in (J102) using a twisted pair to all respective pins in different paralleled units.
Figure 6
NBM evaluation boards
stacked to form a high‑power
parallel array, using common
PGND and both input and
output power terminals
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Limitation of Warranties
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
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02/19
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