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For full details go to
www.murata-ps.com/rohs
　
Figure 1. Connection Diagram
Typical topology is shown. Murata Power Solutions
recommends an external fuse at F1.
RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 1 of 15
FEATURES
391 Watts total output power, 11.85 VDC @ 33 A
Regulated Intermediated Bus Architecture (RIBA)
with PoL converters
96% ultra-high effi ciency at full load (typical)
36 to 75 Volt DC input range (48 VDC nominal)
Standard quarter-brick footprint
Synchronous rectifi er topology with 100 mV
ripple & noise
Up to +85° Celsius thermal performance (with
derating)
Stable no-load operation
Multiple-unit parallel operation for increased
current
Fully isolated to 2250 VDC (BASIC)
Remote On/Off enable control
Extensive protection features – SC, OC, UVLO, OT
Certifi ed to full safety, emissions and environ-
mental standards
Meets UL 60950-1, CAN/CSAC22.2 No. 60950-
1, IEC60950-1, EN60950-1 safety approvals
(2nd Edition)
PRODUCT OVERVIEW
The fully isolated (2250 Vdc) RBQ-12/33-D48
module accepts a 36 to 75 Volt DC input voltage
range (48 VDC nominal) and converts it to a low Vdc
output. Applications include 48V-powered datacom
and telecom installations, base stations, cellular
dataphone repeaters, instruments and embedded
systems. Wideband output ripple and noise is a low
100 mV, peak-to-peak.
The RBQ’s synchronous-rectifi er topology with
line regulation and fi xed frequency operation
means excellent effi ciencies up to 96%, enabling
“no heatsink” operation for most applications up
to +85° Celsius (with derating airfl ow). “No fan” or
zero airfl ow higher temperature applications may
use the optional base plate for cold surface mount-
ing or natural-convection heatsinks.
A wealth of electronic protection features include
input undervoltage lockout (UVLO) , output current
limit, short circuit hiccup, and overtemperature
shutdown. Available options include positive or
negative logic remote On/Off control, conformal
coating, various pin lengths, and the baseplate.
Assembled using ISO-certifi ed automated surface-
mount techniques, the RBQ series is certifi ed to
all UL and IEC emissions, safety and fl ammability
standards.
Typical unit
F1
External
DC
Power
Source
Reference and
Error Amplifier
t4XJUDIJOH
t'JMUFST
t$VSSFOU4FOTF
-Vout (4)
+Vout (8)
On/Off
Control
(2)
-Vin (3)
Open = On
$MPTFE0GG
+Vin (1)
1PTJUJWF
MPHJD
Controller
and Power
5SBOTGFS
Duty Cycle
3FHVMBUJPO
*TPMBUJPO
Barrier
Output (Vout, max) Current (A) Nominal Input (V)
11.85 33 48
FE
AT
UR
ES
Typical uni
t
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PART NUMBER STRUCTURE
RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 2 of 15
Maximum Rated Output
Current in Amps
Maximum Output Voltage (11.85V)
-/D48-
Output Confi guration
RB = Regulated Converter
RB N B
Quarter-Brick Package
Isolated converter
Q
Input Voltage Range
D48 = 36-75V,
48V nominal
PERFORMANCE SPECIFICATIONS SUMMARY AND ORDERING GUIDE
Root Model ➀
Output Input
Effi-
ciency Dimensions (baseplate)
VOUT (V,
max)
IOUT
(A, max)
Total
Power
(W, max)
Ripple & Noise
(mVp-p) Regulation (max.) ➁VIN Nom.
(V)
Range
(V)
IIN, min.
load
(mA)
IIN, full
load
(A)Typ. Max. Line (%) Load (%) Typ. (inches) (mm)
RBQ-12/33-D48 11.85 33 391 100 200 +1/-2 ±3 48 36-75 140 8.59 96% 2.3 x 1.45 x 0.5 58.4 x 36.8 x 12.7
➀ Please refer to the part number structure for additional options and complete ordering part
numbers.
➁ Regulation specifi cations describe the output voltage deviations as the line voltage or load
current is varied from its nominal/midpoint value to either extreme. (Load step = ±25 %). Line
Regulation tested from 40V to 75V, output @nominal load.
➂ All specifi cations are at nominal line voltage and full load, +25 deg.C. unless otherwise noted.
See detailed specifi cations. Output capacitors are 1F, 10uF and 470F in parallel, with a 220F
input capacitor. I/O caps are necessary for our test equipment and may not be needed for your
application.
HS
Conformal coating (optional)
Blank = no coating, standard
H = Coating added, optional*
Load Share Option
Blank = no share
S = Load share
C
-
RoHS Hazardous Materials compliance
C = RoHS 6 (does not claim EU RoHS exemption 7b–lead in solder), standard
Note: Some model number combinations may
not be available. Please contact Murata Power
Solutions for ordering assistance.
On/Off Control Logic Option
N = Negative logic
P = Positive logic
Baseplate
B = Baseplate installed, standard
Lx
(Through-hole packages only)
Blank = Standard pin length 0.180 inches (4.6mm)
L1 = Pin length 0.110 inches (2.79mm)*
L2 = Pin length 0.145 inches (3.68mm)*
Pin Length Option
*Special quantity order is required;
no sample quantities available.
12 33
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RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 3 of 15
FUNCTIONAL SPECIFICATIONS
ABSOLUTE MAXIMUM RATINGS Conditions ➀Minimum Typical/Nominal Maximum Units
Input Voltage, Continuous Full power operation 0 80 Vdc
Input Voltage, Transient Operating or non-operating, 100 mS max.
duration 0 100 Vdc
Isolation Voltage Input to output, 100 mS to IEC/EN/UL 60950-1 2250 Vdc
On/Off Remote Control Power on or off, referred to -Vin 0 15 Vdc
Output Power 0 391 W
Output Current Current-limited, no damage, short-circuit
protected 033A
Storage Temperature Range Vin = Zero (no power) -55 125 °C
Absolute maximums are stress ratings. Exposure of devices to greater than any of these conditions may adversely affect long-term reliability. Proper operation under conditions other than those
listed in the Performance/Functional Specifi cations Table is not implied or recommended.
INPUT
Operating voltage range 36 48 75 Vdc
Recommended External Fuse Fast blow 20 A
Start-up threshold Rising input voltage 32 33.5 35 Vdc
Undervoltage shutdown Falling input voltage 30 31.5 33 Vdc
Internal Filter Type Pi
Input current
Full Load Conditions 8.59 8.68 A
Low Line Vin = minimum 10.8 12 A
Inrush Transient 0.3 A2-Sec.
Output in Short Circuit 0.5 A
No Load Input Current (Iout @ min) Iout = minimum, unit=ON 140 200 mA
Shut-Down Mode Input Current 510mA
Refl ected (back) ripple current ➁Measured at input with specifi ed fi lter 70 200 mA, RMS
GENERAL and SAFETY
Effi ciency Vin=48V, full load 95 96 %
Vin=75V, full load 93 94 %
Isolation
Isolation Voltage, input to output No baseplate 2250 Vdc
Isolation Voltage, input to output With baseplate 2250 Vdc
Isolation Voltage, input to baseplate With baseplate 1500 Vdc
Isolation Voltage, output to baseplate With baseplate 1500 Vdc
Insulation Safety Rating basic
Isolation Resistance 10 Mohm
Isolation Capacitance 1500 pF
Safety Certifi ed to UL-60950-1, CSA-C22.2 No.60950-
1, IEC/EN60950-1, 2nd edition Yes
Calculated MTBF Per Telcordia SR332, issue 1, class 3, ground
fi xed, Tambient=+25°C 1.8 Hours x 106
DYNAMIC CHARACTERISTICS
Fixed Switching Frequency 360 KHz
Startup Delay Power On to Vout regulated, 10-90% Vout,
resistive load 20 mS
Startup Delay Remote ON to 10% of Vout 10 mS
Dynamic Load Response 50-75-50% load step, settling time to within
±2% of Vout 350 µSec
Dynamic Load Peak Deviation Same as above ±400 mV
FEATURES and OPTIONS
Remote On/Off Control ➃
“N” suffi x:
Negative Logic, ON state ON = Pin grounded or external voltage -0.1 0.8 V
Negative Logic, OFF state OFF = Pin open or external voltage 3.5 15 V
Control Current Open collector/drain 1 2 mA
“P” suffi x:
Positive Logic, ON state ON = Pin open or external voltage 2.5 15 V
Positive Logic, OFF state OFF = Ground pin or external voltage 0 1 V
Control Current Open collector/drain 1 2 mA
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RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 4 of 15
OUTPUT Conditions ➀Minimum Typical/Nominal Maximum Units
Total Output Power See Derating 0 386 391 W
Voltage
Nominal Output Voltage Measured @ 48Vin, Half Load. 11.5 11.7 11.85 Vdc
Total Output Range
Over sample load (0-33A), input line (40-75V)
and temperature (see derating curves) , for
regular model and S option
11 12.5 V
Vout Overshoot 12.9 13.1 V
Voltage
Output Voltage
(initial output set point @48V, no load) For S option only 11.7 12.5 Vdc
Output Voltage
(initial output set point @48V, 50% load) For S option only 11.69 11.71 Vdc
Output Voltage
(initial output set point @48V, 100% load) For S option only 11.5 11.7 Vdc
Output Voltage For S option only 11.5 11.7 12.5 Vdc
Overvoltage Protection Output Voltage clamped (see technical note) N/A V
Current
Output Current Range 03333A
Minimum Load No minimum load
Current Limit Inception 98% of Vnom., after warmup 40 46 50 A
Short Circuit
Short Circuit Current Hiccup technique, autorecovery within 1.25%
of Vout 6A
Short Circuit Duration
(remove short for recovery) Output shorted to ground, no damage Continuous
Short circuit protection method Current limiting
Regulation ➄
Line Regulation Vin=40 to 75V +1/-2 %
Load Regulation Iout=min. to max., Vin=48V ±3 %
Ripple and Noise 5 Hz- 20 MHz BW 100 200 mV pk-pk
Temperature Coeffi cient At all outputs 0.003 0.02 % of Vnom./°C
Maximum Capacitive Loading
(10% ceramic, 90% Oscon) Cap. ESR=<0.02, Full resistive load 470 6000 F
MECHANICAL (Through Hole Models)
Outline Dimensions (with baseplate) 2.3 x 1.45 x 0.5 Inches
58.4 x 36.8 x 12.7 mm
Weight (with baseplate) 2.4 Ounces
69 Grams
Through Hole Pin Diameter Input pins 0.04 ±0.001 Inches
1.016±0.025 mm
Through Hole Pin Diameter Output pins 0.060 ±0.001 Inches
1.524±0.025 mm
Through Hole Pin Material Copper alloy
TH Pin Plating Metal and Thickness Nickel subplate 100-299 µ-inches
Gold overplate 3.9-20 µ-inches
ENVIRONMENTAL
Operating Ambient Temperature Range With derating, full power, no condensation,
components +125˚C. max. -40 85 °C
Storage Temperature Vin = Zero (no power) -55 125 °C
Thermal Protection/Shutdown Measured at hotspot 115 125 130 °C
Operating baseplate temperature -40 110 120 °C
Electromagnetic Interference
Conducted, EN55022/CISPR22 External fi lter is required B Class
Relative humidity, non-condensing To +85°C 10 90 %RH
Altitude must derate -1%/1000 feet -500 10,000 feet
-152 3048 meters
RoHS rating RoHS-6
Notes
➀ Unless otherwise noted, all specifi cations are at nominal input voltage, nominal output voltage
and full load. General conditions are +25˚ Celsius ambient temperature, near sea level altitude,
natural convection airfl ow. All models are tested and specifi ed with external parallel 1F, 10F
and 470 F output capacitors and 220 µF external input capacitor. All capacitors are low-ESR
types wired close to the converter. These capacitors are necessary for our test equipment and
may not be needed in the user’s application.
➁ Input (back) ripple current is tested and specifi ed over 5 Hz to 20 MHz bandwidth. Input fi ltering
is Cbus = 220 µF, Cin = 220 µF and Lbus = 4.7 H.
➂ All models are stable and regulate to specifi cation under no load.
➃ The Remote On/Off Control is referred to -Vin.
➄ Regulation specifi cations describe the output voltage changes as the line voltage or load current
is varied from its nominal or midpoint value to either extreme.
FUNCTIONAL SPECIFICATIONS (CONT.)
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PERFORMANCE DATA
RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 5 of 15
Effi ciency and Power Dissipation Current Sharing*
Ta=25°C, Vin=48V
0
5
10
15
25
30
35
40
0
6
12
18
24
30
36
42
48
54
60
66
N
o. 1
L
oa
d
No
. 2 L
oad
T
otal Output Load
(
Amps
)
Current Share Load
(
Amps
)
7
2
7
4
7
6
7
8
80
82
84
86
88
90
92
94
96
98
3
6
9
12
15
18
21
24
2
7
30
33
0
2
4
6
8
10
12
1
4
16
18
2
0
2
2
24
2
6
L
oad
C
u
r
r
e
n
t
(
A
m
p
s
)
E
f
E
E
fi
c
i
e
n
c
y
(
%
)
L
oss
V
I
N
=
36V
V
IN
= 4
8V
V
IN
= 7
5V
Di
ss
i
pat
i
on at 48
V
i
npu
t
*
S
ee Technical note sectio
n
Startup Delay (Vin = 48V, Iout = 33A, Vout = nom, Cload = 470µF, Ta = +25°C)
Ch1 = Vin, Ch2 = Vout
Output ripple and Noise (Vin = 48V, Iout = 0A, Vout = nom,
Cload = 1µF || 10µF || 470µF, Ta = +25°C)
Enable Startup Delay (Vin = 48V, Iout = 33A, Vout = nom, Cload = 470µF, Ta = +25°C)
Ch2 = Vout, Ch4 = Enable
Output ripple and Noise (Vin = 48V, Iout = 33A, Vout = nom,
Cload = 1µF || 10µF || 470µF, Ta = +25°C)
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RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 6 of 15
PERFORMANCE DATA
Step Load Transient Response (Vin = 48V, Iout = 50-75% of Imax, Cload = 470µF,
Slew rate: 1A/uS, Ta = +25 °C.) (-Delta = 278mV, Recovery Time = 164uS)
Step Load Transient Response (Vin = 48V, Iout = 75-50% of Imax, Cload = 470µF,
Slew rate: 1A/uS, Ta = +25 °C.) (-Delta = 266mV, Recovery Time = 156uS)
Step Load Transient Response (Vin = 48V, Iout = 50-75-50% of Imax,
Cload = 470µF, Slew rate: 1A/uS, Ta = +25 °C.)
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PERFORMANCE DATA
RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 7 of 15
Maximum Current Temperature Derating in Transverse Direction
Vin= 40V (air fl ow is from -Vin to +Vin), with baseplate
Maximum Current Temperature Derating in Longitudinal Direction
Vin= 40V (air fl ow is from Vin to Vout), with baseplate
0
5
1
0
1
5
2
0
2
5
3
0
3
5
4
0
3
0
3
5
4
0
4
5
5
0
5
5
6
0
6
5
7
0
7
5
8
0
8
5
Output Current (Amps
)
Ambient Temperature
(
ºC
)
0
.5 m
/
s (100LFM
)
1
.0 m/s
(
200LFM
)
1
.5 m
/
s (300LFM
)
2
.0 m/s (400LFM
)
2
.5 m
/
s (500LFM
)
3.0 m/s (600LFM
)
0
5
1
0
1
5
2
0
2
5
3
0
3
5
3
0
3
5
4
0
4
5
5
0
5
5
6
0
6
5
7
0
7
5
8
0
8
5
O
utput
C
urrent
(
Amps
)
Ambient Temperature
(
º
C)
0
.5 m/s
(
100LFM
)
1
.0 m
/
s
(
200LFM
)
1
.5 m
/
s
(
300LFM
)
2.0 m/s
(
400LFM
)
2.5 m
/
s
(
500LFM
)
3
.0 m
/
s
(
600LFM
)
Maximum Current Temperature Derating in Transverse Direction
Vin= 48V (air fl ow is from -Vin to +Vin), with baseplate
0
5
1
0
1
5
2
0
2
5
3
0
3
5
4
0
3
0
3
5
4
0
4
5
5
0
5
5
6
0
6
5
7
0
7
5
8
0
8
5
O
utput
C
urrent (Amps)
Ambient Temperature (º
C
)
0
.5 m
/
s
(
100LFM
)
1.0 m
/
s (200LFM
)
1.5 m
/
s (300LFM
)
2.0 m
/
s (400LFM
)
2.5 m
/
s (500LFM
)
3
.0 m
/
s (600LFM
)
Maximum Current Temperature Derating in Longitudinal Direction
Vin= 48V (air fl ow is from Vin to Vout), with baseplate
0
5
1
0
1
5
2
0
2
5
3
0
3
5
3
0
3
5
4
0
4
5
5
0
5
5
6
0
6
5
7
0
7
5
8
0
8
5
Output Current (Amps)
Ambient Temperature (ºC)
0
.5 m/s
(
100LFM
)
1.0 m/s (200LFM)
1.5 m/s (300LFM)
2
.0 m/s (400LFM)
2
.5 m/s (500LFM)
3
.0 m
/
s (600LFM)
Maximum Current Temperature Derating in Longitudinal Direction
Vin= 75V (air fl ow is from Vin to Vout), with baseplate
0
5
1
0
1
5
2
0
2
5
3
0
3
5
3
0
3
5
4
0
4
5
5
0
5
5
6
0
6
5
7
0
7
5
8
0
8
5
Output Current (Amps)
Ambient Temperature (ºC)
0.5 m/s (100LFM)
1.0 m/s (200LFM)
1.5 m/s (300LFM)
2.0 m/s
(
400LFM
)
2.5 m/s (500LFM)
3.0 m/s (600LFM)
Maximum Current Temperature Derating in Transverse Direction
Vin= 75V (air fl ow is from -Vin to +Vin), with baseplate
0
5
1
0
1
5
2
0
2
5
3
0
3
5
4
0
3
0
3
5
4
0
4
5
5
0
5
5
6
0
6
5
7
0
7
5
8
0
8
5
O
utput
C
urrent
(
Amps
)
Ambient Temperature (ºC)
0
.5 m/s (100LFM)
1
.0 m/s (200LFM)
1
.5 m/s (300LFM)
2
.0 m/s (400LFM)
2
.5 m/s (500LFM)
3
.0 m/s
(
600LFM
)
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RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 8 of 15
MECHANICAL SPECIFICATIONS (THROUGH-HOLE MOUNT)
Third Angle Projection
Dimensions are in inches (mm shown for ref. only).
Components are shown for reference only
and may vary between units.
Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 2˚
INPUT/OUTPUT CONNECTIONS
Pin Function
1 +Vin
2 Remote On/Off
3 −Vin
4 −Vout
8 +Vout
The 0.145" (L2) pin length is shown.
Please refer to the part number structure
for alternate pin lengths.
2.000 (50.8)
1.45 (36.8)
2.30 (58.42)
0.600 (15.24)
0.600 (15.24)
0.50
(12.7)
BASEPLATE OPTION
BOTTOM VIEW
SIDE VIEW
BASEPLATE OPTION
TOP VIEW
1.860 (47.24)
0.210
(5.33)
0.220
(5.59)
1.030 (26.16)
L
ij0.062±0.002(1.575±0.05)
highest component
between standoffs and
0.010 minimum clearance PINS 1-3:
ij0.040±0.002(1.016±0.05)
PINS 4,5:
SEE NOTE 6
NOTES:
UNLESS OTHERWISE SPECIFIED:
1:M3 SCREW USED TO BOLT UNIT'S BASEPLATE TO OTHER SURFACES(SUCH AS
HEATSINK)
MUST NOT EXCEED 0.098''(2.5mm) DEPTH BELOW THE SURFACE OF BASEPLATE
2:APPLIED TORQUE PER SCREW SHOULD NOT EXCEED 5.3In-lb(0.6Nm);
3:ALL DIMENSION ARE IN INCHES[MILIMETER];
4:ALL TOLERANCES: ×.××in, ±0.02in(×.×mm,±0.5mm)
×.×××in ,±0.01in(×.××mm,±0.25mm)
5:COMPONENT WILL VARY BETWEEN MODELS
6:STANDARD PIN LENGTH: 0.180 Inch
FOR L2 PIN LENGTH OPTION IN MODEL NAME, SEE PART NUMBER STRUCTURE.
3
2
81
4
M3 TYP 3PL
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SHIPPING TRAYS AND BOXES, THROUGH-HOLE MOUNT
SHIPPING TRAY DIMENSIONS
RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 9 of 15
30 CONVERTERS PER CARTON
CARTON ACCOMMODATES
TWO (2) TRAYS YIELDING
MPQ=30
±.2511.00 ±.2510.50
2.75±0.25
CLOSED HEIGHT
EACH STATIC DISSIPATIVE
POLYETHYLENE FOAM TRAY
ACCOMMODATES 15 CONVERTERS
IN A 3 X 5 ARRAY
9.92
REF REF
9.92
0.88
REF
RBQ modules are supplied in a 15-piece (5 x 3) shipping tray. The tray is an anti-static closed-cell polyethylene foam. Dimensions are shown below.
Notes:
Material: Dow 220 antistat ethafoam1.
(Density: 34-35 kg/m3)
Dimensions: 252 x 252 x 19.1 mm2.
5 x 3 array (15 per tray)
3. All dimensions in millimeters [inches]
4. Tolerances unless otherwise specified: +1/-0
[9.92]
252.0
L
36.83
[1.450]
TYP
TYP
18.67 [0.735]
60.96 [2.400]
TYP
15.875 [0.625]
18.42
[0.725] TYP
C
6.35 [.25] CHAMFER
TYP (4-PL)
6.35 [.25] R TYP
-.062
+.000
[9.92]
252.0
-.062
+.000
46.36
[1.825] TYP
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Thermal Shutdown
Extended operation at excessive temperature will initiate overtemperature
shutdown triggered by a temperature sensor inside the PWM controller. This
operates similarly to overcurrent and short circuit mode. The inception point
of the overtemperature condition depends on the average power delivered,
the ambient temperature and the extent of forced cooling airfl ow. Thermal
shutdown uses only the hiccup mode (autorestart).
Parallel Load Sharing (S Option, Load Sharing)
Two or more converters may be connected in parallel at both the input and
output terminals to support higher output current (total power, see fi gure 2) or to
improve reliability due to the reduced stress that results when the modules are
operating below their rated limits. For applications requiring current share, follow
the guidelines below. See specifi cation table for Output Voltage set points. The
stated output voltage set point is trimmed to a very narrow range (11.7V ±10mV
@48Vin, 50% load). The output voltage will decrease when the load current is
increased. Our goal is to have each converter contribute nearly identical current
into the output load under all input, environmental and load conditions.
Using Parallel Connections – Load Sharing (Power Boost)
All converters must be powered up and powered down simultaneously. Use
a common input power source.
It is required to use a common Remote On/Off logic control signal to turn on
modules (see fi gure 2).
When Vin has reached steady state, apply control signal to the all modules.
Figure 3 illustrates the turn on process for positive logic modules.
First power up the parallel system (all converters) with a load not exceed-
ing the rated load of each converter and allow converters to settle (typically
20-100mS) before applying full load. As a practical matter, if the loads are
downstream PoL converters, power these up shortly after the converter has
reached steady state output. Also be aware of the delay caused by charging
up external bypass capacitors.
It is critical that the PCB layout incorporates identical connections from each
module to the load; use the same trace rating and airfl ow/thermal environ-
ments. If you add input fi lter components, use identical components and layout.
When converters are connected in parallel, allow for a safety factor of at
least 10%. Up to 90% of max output current can be used from each module.
TECHNICAL NOTES
CAUTION: This converter is not internally fused. To avoid danger to persons
or equipment and to retain safety certifi cation, the user must connect an
external fast-blow input fuse as listed in the specifi cations. Be sure that the PC
board pad area and etch size are adequate to provide enough current so that
the fuse will blow with an overload.
Using Parallel Connections – Redundancy (N+1)
The redundancy connections in fi gure 4 requires external user supplied
“OR”ing diodes or “OR”ing MOSFETs for reliability purposes. The diodes allow
for an uninterruptable power system operation in case of a catastrophic failure
(shorted output) by one of the converters.
The diodes should be identical part numbers to enhance balance between
the converters. The default factory nominal voltage should be suffi ciently
matched between converters. The OR’ing diode system is the responsibility of
the user. Be aware of the power levels applied to the diodes and possible heat
sink requirements.
Schottky power diodes with approximately 0.3V drops or “OR”ing MOSFETs
may be suitable in the loop whereas 0.7 V silicon power diodes may not be
advisable. In the event of an internal device fault or failure of the mains power
RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 10 of 15
Figure 2. Load Sharing Block Diagram
On/Off
On/Off
On/Off
F1
F2
F3
+
+
–
–
+
–
+Vin +Vout
–Vin –Vout
–Vin –Vout
–Vin –Vout
+Vin +Vout
+Vin +Vout
LOAD
Input
Source
On/Off Signal
Input
Filter
On/Off
Vout
Vin
CH2
CH2 = On/Off
CH3
CH3 = Vout
CH1
CH1 = Vin
Figure 3. Typical Turn On for Positive Logic Modules
Figure 4. Redundant Parallel Connections
On/Off
On/Off
On/Off
F1
F2
F3
+
+
–
–
+
–
+Vin +Vout
–Vin –Vout
–Vin –Vout
–Vin –Vout
+Vin +Vout
+Vin +Vout
LOAD
Input
Source
On/Off Signal
Input
Filter
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RBQ-12/33-D48
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MDC_RBQ-12/33-D48.A01Δ Page 11 of 15
modules on the primary side, the other devices automatically take over the
entire supply of the loads. In the basic N+1 power system, the “N” equals the
number of modules required to fully power the system and “+1” equals one
back-up module that will take over for a failed module. If the system consists
of two power modules, each providing 50% of the total load power under
normal operation and one module fails, another one delivers full power to the
load. This means you can use smaller and less expensive power converters as
the redundant elements, while achieving the goal of increased availability.
Start Up Considerations
When power is fi rst applied to the DC-DC converter, there is some risk of start
up diffi culties if you do not have both low AC and DC impedance and adequate
regulation of the input source. Make sure that your source supply does not allow
the instantaneous input voltage to go below the minimum voltage at all times.
Use a moderate size capacitor very close to the input terminals. You may
need two or more parallel capacitors. A larger electrolytic or ceramic cap sup-
plies the surge current and a smaller parallel low-ESR ceramic cap gives low
AC impedance.
Remember that the input current is carried both by the wiring and the
ground plane return. Make sure the ground plane uses adequate thickness
copper. Run additional bus wire if necessary.
Input Fusing
Certain applications and/or safety agencies may require fuses at the inputs of
power conversion components. Fuses should also be used when there is the
possibility of sustained input voltage reversal which is not current-limited. For
greatest safety, we recommend a fast blow fuse installed in the ungrounded
input supply line.
Input Under-Voltage Shutdown and Start-Up Threshold
Under normal start-up conditions, converters will not begin to regulate properly
until the rising input voltage exceeds and remains at the Start-Up Threshold
Voltage (see Specifi cations). Once operating, converters will not turn off until
the input voltage drops below the Under-Voltage Shutdown Limit. Subsequent
restart will not occur until the input voltage rises again above the Start-Up
Threshold. This built-in hysteresis prevents any unstable on/off operation at a
single input voltage.
Start-Up Time
Assuming that the output current is set at the rated maximum, the Vin to Vout
Start-Up Time (see Specifi cations) is the time interval between the point when
the rising input voltage crosses the Start-Up Threshold and the fully loaded
output voltage enters and remains within its specifi ed accuracy band. Actual
measured times will vary with input source impedance, external input capaci-
tance, input voltage slew rate and fi nal value of the input voltage as it appears
at the converter.
These converters include a soft start circuit to moderate the duty cycle of its
PWM controller at power up, thereby limiting the input inrush current.
The On/Off Remote Control interval from On command to Vout (fi nal ±5%)
assumes that the converter already has its input voltage stabilized above the
Start-Up Threshold before the On command. The interval is measured from the
On command until the output enters and remains within its specifi ed accuracy
band. The specifi cation assumes that the output is fully loaded at maximum
rated current. Similar conditions apply to the On to Vout regulated specifi cation
such as external load capacitance and soft start circuitry.
Recommended Input Filtering
The user must assure that the input source has low AC impedance to provide
dynamic stability and that the input supply has little or no inductive content,
including long distributed wiring to a remote power supply. The converter will
operate with no additional external capacitance if these conditions are met.
For best performance, we recommend installing a low-ESR capacitor
immediately adjacent to the converter’s input terminals. The capacitor should
be a ceramic type such as the Murata GRM32 series or a polymer type. Make
sure that the input terminals do not go below the undervoltage shutdown volt-
age at all times. More input bulk capacitance may be added in parallel (either
electrolytic or tantalum) if needed.
Recommended Output Filtering
The converter will achieve its rated output ripple and noise with no additional
external capacitor. However, the user may install more external output capaci-
tance to reduce the ripple even further or for improved dynamic response.
Again, use low-ESR ceramic (Murata GRM32 series) or polymer capacitors.
Mount these close to the converter. Measure the output ripple under your load
conditions.
Use only as much capacitance as required to achieve your ripple and noise
objectives. Excessive capacitance can make step load recovery sluggish or
possibly introduce instability. Do not exceed the maximum rated output capaci-
tance listed in the specifi cations.
Input Ripple Current and Output Noise
All models in this converter series are tested and specifi ed for input refl ected
ripple current and output noise using designated external input/output com-
ponents, circuits and layout as shown in the fi gures below. The Cbus and Lbus
components simulate a typical DC voltage bus.
Minimum Output Loading Requirements
All models regulate within specifi cation and are stable under no load to full
load conditions. Operation under no load might however slightly increase
output ripple and noise.
C
IN
V
IN
C
BUS
L
BUS
C
IN
= 220F (100V), ESR < 700mΩ @ 100kHz
C
BUS
= 220F (100V), ESR < 100mΩ @ 100kHz
L
BUS
= 4.7H
+Vin
-Vin
CURRENT
PROBE
TO
OSCILLOSCOPE
+
–
+
–
Figure 5. Measuring Input Ripple Current
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Thermal Shutdown
To prevent many over temperature problems and damage, these converters
include thermal shutdown circuitry. If environmental conditions cause the
temperature of the DC-DCs to rise above the Operating Temperature Range
up to the shutdown temperature, an on-board electronic temperature sensor
will power down the unit. When the temperature decreases below the turn-on
threshold, the converter will automatically restart. There is a small amount of
hysteresis to prevent rapid on/off cycling.
CAUTION: If you operate too close to the thermal limits, the converter may
shut down suddenly without warning. Be sure to thoroughly test your applica-
tion to avoid unplanned thermal shutdown.
Temperature Derating Curves
The graphs in this data sheet illustrate typical operation under a variety of
conditions. The Derating curves show the maximum continuous ambient air
temperature and decreasing maximum output current which is acceptable
under increasing forced airfl ow measured in Linear Feet per Minute (“LFM”).
Note that these are AVERAGE measurements. The converter will accept brief
increases in current or reduced airfl ow as long as the average is not exceeded.
Note that the temperatures are of the ambient airfl ow, not the converter
itself which is obviously running at higher temperature than the outside air.
Also note that “natural convection” is defi ned as very fl ow rates which are not
using fan-forced airfl ow. Depending on the application, “natural convection” is
usually about 30-65 LFM but is not equal to still air (0 LFM).
Murata Power Solutions makes Characterization measurements in a closed
cycle wind tunnel with calibrated airfl ow. We use both thermocouples and an
infrared camera system to observe thermal performance. As a practical matter,
it is quite diffi cult to insert an anemometer to precisely measure airfl ow in
most applications. Sometimes it is possible to estimate the effective airfl ow if
you thoroughly understand the enclosure geometry, entry/exit orifi ce areas and
the fan fl owrate specifi cations.
CAUTION: If you exceed these Derating guidelines, the converter may have
an unplanned Over Temperature shut down. Also, these graphs are all collected
near Sea Level altitude. Be sure to reduce the derating for higher altitude.
Output Fusing
The converter is extensively protected against current, voltage and tempera-
ture extremes. However your output application circuit may need additional
protection. In the extremely unlikely event of output circuit failure, excessive
voltage could be applied to your circuit. Consider using an appropriate fuse in
series with the output.
Output Current Limiting
Current limiting inception is defi ned as the point at which full power falls below
the rated tolerance. See the Performance/Functional Specifi cations. Note par-
ticularly that the output current may briefl y rise above its rated value in normal
operation as long as the average output power is not exceeded. This enhances
reliability and continued operation of your application. If the output current is
too high, the converter will enter the short circuit condition.
Output Short Circuit Condition
When a converter is in current-limit mode, the output voltage will drop as the
output current demand increases. If the output voltage drops too low (approxi-
mately 97% of nominal output voltage for most models), the PWM controller
will shut down. Following a time-out period, the PWM will restart, causing
the output voltage to begin rising to its appropriate value. If the short-circuit
condition persists, another shutdown cycle will initiate. This rapid on/off cycling
is called “hiccup mode.” The hiccup cycling reduces the average output cur-
rent, thereby preventing excessive internal temperatures and/or component
damage. A short circuit can be tolerated indefi nitely.
The “hiccup” system differs from older latching short circuit systems
because you do not have to power down the converter to make it restart. The
system will automatically restore operation as soon as the short circuit condi-
tion is removed.
Remote On/Off Control
On the input side, a remote On/Off Control can be specifi ed with either logic
type. Please refer to the Connection Diagram on page 1 for On/Off connections.
Positive-logic models are enabled when the On/Off pin is left open or is
pulled high to +15V with respect to –VIN. Positive-logic devices are disabled
when the On/Off is grounded or brought to within a low voltage (see Specifi ca-
tions) with respect to –VIN.
Negative-logic models are on (enabled) when the On/Off is grounded or
brought to within a low voltage (see Specifi cations) with respect to –VIN. The
device is off (disabled) when the On/Off is left open or is pulled high to +15VDC
Max. with respect to –VIN.
Dynamic control of the On/Off function should be able to sink specifi ed
signal current when brought low and withstand specifi ed voltage when brought
high. Be aware too that there is a fi nite time in milliseconds (see Specifi cations)
between the time of On/Off Control activation and stable output. This time will
vary slightly with output load type and current and input conditions.
Output Capacitive Load
These converters do not require external capacitance added to achieve
rated specifi cations. Users should only consider adding capacitance to reduce
switching noise and/or to handle spike current load steps. Install only enough
capacitance to achieve noise objectives. Excess external capacitance may
cause degraded transient response and possible oscillation or instability.
C1 = 1µF
C2 = 10µF
C3 = 470µF
R
LOAD
C2 C3
C1 SCOPE
+VOUT
-VOUT
Figure 6. Measuring Output Ripple and Noise (PARD)
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Output OVP (Output Clamped)
The RBQ-12/33-D48 module incorporates circuitry to protect the output/load
(Output OVP, Over Voltage Protection) by effectively clamping the output volt-
age to a maximum of 13.1V under certain fault conditions. The initial output
voltage is set at the factory for an accuracy of ±1.5%, and is regulated over
line load and temperature using a closed loop feedback system. In the event
of a failure that causes the module to operate open loop (failure in the control
loop), the output voltage will be determined by the input voltage/duty cycle of
the voltage conversion (Pulse Width Modulation) circuit. For example, when
the input voltage is at 36V, the duty cycle is D1; when the input voltage is at
75V, the maximum duty cycle is D1/2; this change in duty cycle compensates
Vout for Vin changes. As Vin continues to increase above 75V the voltage at
Vout is clamped because maximum duty cycle has been reached. The output
voltage is always proportional to Vin*Duty in a buck derived topology. Figure 4
is the test waveform for the RBQ-12/33-D48 module when its feedback loop is
open, simulating a loop failure. Channel 1 is the input voltage and Channel 2 it
the output voltage. When the input voltage climbs from 48Vdc to 100Vdc, the
output voltage remains stable. Figure 7. Test Waveform with Feedback Loop Open
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RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 14 of 15
Emissions Performance, Model RBQ-12-33-D48
Murata Power Solutions measures its products for radio frequency emissions
against the EN 55022 and CISPR 22 standards. Passive resistance loads are
employed and the output is set to the maximum voltage. If you set up your
own emissions testing, make sure the output load is rated at continuous power
while doing the tests.
The recommended external input and output capacitors (if required) are
included. Please refer to the fundamental switching frequency. All of this
information is listed in the Product Specifi cations. An external discrete fi lter is
installed and the circuit diagram is shown below.
[1] Conducted Emissions Parts List
[2] Conducted Emissions Test Equipment Used
Hewlett Packard HP8594L Spectrum Analyzer – S/N 3827A00153
2Line V-networks LS1-15V 50/50Uh Line Impedance Stabilization Network
[3] Conducted Emissions Test Results
[4] Layout Recommendations
Most applications can use the fi ltering which is already installed inside the
converter or with the addition of the recommended external capacitors. For
greater emissions suppression, consider additional fi lter components and/or
shielding. Emissions performance will depend on the user’s PC board layout,
the chassis shielding environment and choice of external components. Please
refer to Application Note GEAN-02 for further discussion.
Since many factors affect both the amplitude and spectra of emissions, we
recommend using an engineer who is experienced at emissions suppression.
Reference Part Number Description Vendor
C1, C2, C3, C4, C5 GRM32ER72A105KA01L SMD CERAMIC-100V-
1000nF-X7R-1210 Murata
C6 GRM319R72A104KA01D SMD CERAMIC100V-100nF-
±10%-X7R-1206 Murata
L1, L2 PG0060T COMMON MODE-473uH-
±25%-14A Pulse
C8, C9, C10, C11 GRM55DR72J224KW01L SMD CERAMIC630V-0.22uF-
±10%-X7R-2220 Murata
C7 UHE2A221MHD Aluminum100V-220Uf-
±10%-long lead Nichicon
C12 NA
LOAD
C2 L1
C6 C7 DC/DC C12
++
VCC
RTN
-48V
GND
GND
C3C1 L2
C5C4
C8 C9 C10 C11
Figure 8. Conducted Emissions Test Circuit
Graph 1. Conducted emissions performance, Positive Line,
CISPR 22, Class B, full load
Graph 2. Conducted emissions performance, Negative Line,
CISPR 22, Class B, full load
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Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifi cations are subject to change without
notice. © 2013 Murata Power Solutions, Inc.
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to: http://www.murata-ps.com/requirements/
RBQ-12/33-D48
Quarter-Brick 400-Watt Isolated DC-DC Converters
MDC_RBQ-12/33-D48.A01Δ Page 15 of 15
Soldering Guidelines
Murata Power Solutions recommends the specifi cations below when installing these converters. These specifi cations vary depending on the solder type. Exceeding these specifi ca-
tions may cause damage to the product. Your production environment may differ; therefore please thoroughly review these guidelines with your process engineers.
Wave Solder Operations for through-hole mounted products (THMT)
For Sn/Ag/Cu based solders: For Sn/Pb based solders:
Maximum Preheat Temperature 115° C. Maximum Preheat Temperature 105° C.
Maximum Pot Temperature 270° C. Maximum Pot Temperature 250° C.
Maximum Solder Dwell Time 7 seconds Maximum Solder Dwell Time 6 seconds
Figure 9. Vertical Wind Tunnel
IR Video
Camera
IR Transparent
optical window Variable
speed fan
Heating
element
Ambient
temperature
sensor
Airflow
collimator
Precision
low-rate
anemometer
3” below UUT
Unit under
test (UUT)
Vertical Wind Tunnel
Murata Power Solutions employs a computer controlled
custom-designed closed loop vertical wind tunnel, infrared
video camera system, and test instrumentation for accurate
airfl ow and heat dissipation analysis of power products.
The system includes a precision low fl ow-rate anemometer,
variable speed fan, power supply input and load controls,
temperature gauges, and adjustable heating element.
The IR camera monitors the thermal performance of the
Unit Under Test (UUT) under static steady-state conditions. A
special optical port is used which is transparent to infrared
wavelengths.
Both through-hole and surface mount converters are
soldered down to a 10"x 10" host carrier board for realistic
heat absorption and spreading. Both longitudinal and trans-
verse airfl ow studies are possible by rotation of this carrier
board since there are often signifi cant differences in the heat
dissipation in the two airfl ow directions. The combination of
adjustable airfl ow, adjustable ambient heat, and adjustable
Input/Output currents and voltages mean that a very wide
range of measurement conditions can be studied.
The collimator reduces the amount of turbulence adjacent
to the UUT by minimizing airfl ow turbulence. Such turbu-
lence infl uences the effective heat transfer characteristics
and gives false readings. Excess turbulence removes more
heat from some surfaces and less heat from others, possibly
causing uneven overheating.
Both sides of the UUT are studied since there are different
thermal gradients on each side. The adjustable heating element
and fan, built-in temperature gauges, and no-contact IR camera mean
that power supplies are tested in real-world conditions.
Mouser Electronics
Authorized Distributor
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