Datasheet UCE Datasheet (MURATA)

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FEATURES

■

RoHS-6 or RoHS-5 compliant

■

Industry standard eighth-brick pinout

and package

■

Outputs from 1.5V to 12V up to 100W

■

Low profi le 0.4" height with 0.9" x 2.3"

outline dimensions

■

36 to 75 Vdc input range (48V nominal)

■

Fully isolated, 2250 Vdc (BASIC)

insulation

■

Outstanding thermal performance

and derating

■

Extensive self-protection and short

circuit features with no output reverse
conduction

■

On/Off control, trim and sense functions

■

Interleaved synchronous rectifi cation

yields high effi ciency over 90%

■

Fully protected against temperature and

voltage limits

■

Certifi ed to UL/EN/IEC 60950-1 and

CAN/CSA C22.2 No. 60950-1 safety
approvals

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

Typical unit

For effi cient, fully isolated DC power in the smallest space, the UCE
open frame DC/DC converter series fi t in industry-standard “eighth
brick” outline dimensions and mounting pins (on quarter-brick pinout).

PRODUCT OVERVIEW

Units are offered with fi xed output voltages from

1.5 to 12 Volts and currents up to 30 Amps. UCEs
operate over a wide temperature range (up to +85
degrees Celsius at moderate airfl ow) with full rated
power. Interleaved synchronous rectifi er topology
yields excellent effi ciency over 90% and no reverse
output conduction.

UCEs achieve these impressive mechanical and
environmental specs while delivering excellent
electrical performance in a through-hole package.
Overall noise is typically 50 mV pk-pk (low voltage
models) with fast step response. These converters
offer tight output regulation and high stability even
with no load. The unit is fully protected against
input undervoltage, output overcurrent and short
circuit. An on-board temperature sensor shuts

down the converter if thermal limits are reached.
“Hiccup” output protection automatically restarts
the converter when the fault is removed.

A convenient remote On/Off control input enables
phased startup and shutdown in multi-voltage ap­plications. To compensate for longer wiring and to
retain output voltage accuracy at the load, UCEs em­ploy a Sense input to dynamically correct for ohmic
losses. A trim input may be connected to a user’s
adjustment potentiometer or trim resistors for output
voltage calibration. The UCE will tolerate substantial
capacitive loading for bypass-cap applications.

UCEs include industry-standard safety certifi ca­tions and BASIC I/O insulation provides input/output
isolation to 2250V. Radiation emission testing is
performed to widely-accepted EMC standards.

SIMPLIFIED BLOCK DIAGRAM

+V

IN

(3)

–V

IN

(1)

REMOTE

ON/OFF

CONTROL

(2)

For full details go to

www.murata-ps.com/rohs

TRANSFORMER

PWM

CONTROLLER

Figure 1. Simplifi ed Block Diagram

OPTO

ISOLATION

SWITCH

CONTROL

PULSE

INPUT UNDERVOLTAGE, INPUT
OVERVOLTAGE, AND OUTPUT
OVERVOLTAGE COMPARATORS

REFERENCE &

ERROR AMP

Typical topology is shown.

+SENSE

(7)

+V

OUT

(8)

−V

OUT

(4)

−SENSE
(5)

V

OUT

TRIM

(6)

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13 Nov 2009 MDC_UCE.A24_long Page 1 of 16

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

PERFORMANCE SPECIFICATIONS AND ORDERING GUIDE

Output Input

Ripple & Noise

OUT

(V)

I
(A)

OUT

Power

(W)

Model Family

V

UCE-1.2/25-D48N-C 1.2 25 30 Please contact Murata Power Solutions for further information.
UCE-1.5/20-D48N-C 1.5 20 30 50 100 ±0.15% ±0.3% 48 36-75 50 0.72 85% 87% C56 P32
UCE-1.5/40-D48N-C 1.5 40 60 Please contact Murata Power Solutions for further information.
UCE-1.8/30-D48N-C 1.8 30 54 30
UCE-2.5/20-D48N-C 2.5 20 50
UCE-3.3/15-D48N-C 3.3 15 49.5
UCE-3.3/30-D48N-C 3.3 30 99 ±0.1% ±0.2% 2.27 89% 91%
UCE-5/10-D48N-C 51050
UCE-5/20-D48N-C 5 20 100 30 60
UCE-12/4.2-D48N-C 12 4.2 50.4 150
UCE-12/8.3-D48N-C 12 8.3 99.6 200 2.31 90%

M Please refer to the model number structure for additional ordering part numbers and options .

PART NUMBER STRUCTURE

(mVp-p) Regulation (max.)

80

±0.125% ±0.25%

50

100

±0.125% ±0.25%

300

IN Nom.

V

(V)

48 36-75

Range

(V)

IIN, no

IIN, full

load

(mA)

load

(A)Typ. Max. Line Load Min. Typ. Case Pinout

45 1.28 87% 88%
50 1.14 88% 91%

1.15 86% 90%

60

30 1.15 88% 90.5%

2.25 90% 92.5%

50

1.14

Effi ciency Package

86%

C56 P32

92%

/

U CE -

Output Confi guration:

U = Unipolar/Single

Eighth-Brick Package

Nominal Output Voltage

Maximum Rated Output

Current in Amps

Input Voltage Range:

D48 = 36-75V,
48V nominal

30 N B

D48-3.3

On/Off Control Polarity

N = Negative polarity, standard
P = Positive polarity, optional

Baseplate (optional, not available on some models)

Blank = No baseplate, standard
B = Baseplate installed, optional, special quantity order

Product Adaptations

Murata Power Solutions offers several variations of our core product family.
These products are available under scheduled quantity orders and may also
include separate manufacturing documentation from a mutually agreeable
Product Specifi cation. Since these product adaptations largely share a common
parts list and similar specifi cations and test methods with their root products,
they are provided at excellent costs and delivery. Please contact Murata Power
Solutions for details.

H

LX

-

C

RoHS Hazardous Materials compliance

C = RoHS6 (does not claim EU RoHS exemption 7b–lead in solder), standard
Y = RoHS5 (with lead), optional, special quantity order

(Through-hole packages only)

Pin Length Option

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)*
* Special quantity order is required.

Conformal coating (optional)

Blank = no coating, standard
H = Coating added, optional, special quantity order

Note: Some model combinations may not be
available. Contact Murata Power Solutions for
availability.

As of this date, the following products are available:

UCE-3.3/30-D48NHL2-Y

UCE-12/4.2-D48NHL2-Y
These models are all negative On/Off polarity, no baseplate, conformal coating
added, 3.68mm pin length, and RoHS-5 hazardous substance compliance (with
lead).

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13 Nov 2009 MDC_UCE.A24_long Page 2 of 16

SPECIFICATIONS

INPUT CHARACTERISTICS

Start-up

Model Family

UCE-1.5/20-D48
UCE-1.8/30-D48
UCE-2.5/20-D48
UCE-3.3/15-D48
UCE-3.3/30-D48
UCE-5/10-D48
UCE-5/20-D48
UCE-12/4.2-D48
UCE-12/8.3-D48

OUTPUT CHARACTERISTICS

threshold

Under-

Reflected

voltage

Min.

34.5 32 1.53 Pi

Shut­down

(A)

34

34 31.5 3.00 Pi

34

(back)
Ripple

Current

(V)

(mA)②

32

32.5 1.72
32 1.53
32 1.54

10-30,

model

32 3.06

dependent

32 1.52
32 3.07

Inrush

Transient

A

A

2

sec

0.05

2

sec

Output

Short

Circuit

(mA)

50-150,

model

dependent

Low Line

(VIN=min.)

(A)

0.97

Standby

Mode

(mA)

1-10,

model

dependent

Internal

Input Filter

Type

L-C

L-C

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

Reverse
Polarity

Protection

None, install

external fuse

Remote On/Off Control

Positive Logic

Current

(mA)

1.0

“P” Model

OFF=Ground

pin to +1V max.

ON=open or

+3.5 to +15V

Suffix

max.

Negative Logic

“N” Model

OFF=open or

+15V max.

ON=Ground pin to

+0.8V max.

Suffix

+2.5V to

VOUT

Accuracy

Model Family

50% Load
% of VNOM

UCE-1.5/20-D48
UCE-1.8/30-D48
UCE-2.5/20-D48
UCE-3.3/15-D48
UCE-3.3/30-D48

±1%

UCE-5/10-D48
UCE-5/20-D48
UCE-12/4.2-D48
UCE-12/8.3-D48

ISOLATION CHARACTERISTICS

Input to Output

Model Family

UCE-1.5/20-D48
UCE-1.8/30-D48 10

Capacitive

Loading Max. Low

ESR <0.02Ω Max.μFAdjustment

10,000
10,000 36
10,000 32
10,000 24
10,000 35

1000 15.

10,000 23 min.

1000 5.5
1000 12

Min.

V

Range

–10 to

+10% of

Vnom.

Input to

baseplate

Min.

V

Temperature

Coeffi cient

±0.02% of
Vout range

per °C

Baseplate to output

Min.

Minimum

Loading

No minimum

load

V

Remote

Sense

Compen-

sation

+10% See ordering guide

Isolation

Resistance

MΩ

100

UCE-2.5/20-D48

UCE-3.3/15-D48
UCE-3.3/30-D48

UCE-5/10-D48

2250 1500 1500

100

UCE-5/20-D48

UCE-12/4.2-D48
UCE-12/8.3-D48

Ripple/

Noise

(20 MHz

bandwidth)

Current Limit

Inception

Line/Load

Regulation Effi ciency

Isolation

Capacitance

pF Isolation Safety Rating

1000

98% of Vout,

after warmup

Basic Insulation

A

24.5

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13 Nov 2009 MDC_UCE.A24_long Page 3 of 16

SPECIFICATIONS, CONTINUED

MISCELLANEOUS CHARACTERISTICS

Calculated

Model Family

UCE-1.5/20-D48
UCE-1.8/30-D48
UCE-2.5/20-D48
UCE-3.3/15-D48
UCE-3.3/30-D48
UCE-5/10-D48
UCE-5/20-D48
UCE-12/4.2-D48
UCE-12/8.3-D48

4

MTBF

TBC

1.8 M HRS 3

TBC 4.25

2.6 M HRS

2.7 M HRS
TBC

2.4 M HRS

Operating

Temperature Range

with derating

(°C)

−40 to +85

Operating

PCB
Temperature
(no derating)

−40 to +110
(model

dependent)

Storage

Temperature

Range

(°C)

−55 to
+125

Thermal

Protection/

Shutdown

(ºC)

120 5

110 0.5 7 max.

125 5 14.5

Short

Circuit

Current

(A)

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

Overvoltage
Protection

(V) Via
magnetic
feedback

(V)

1.95

2.8 V. max

12

Short Circuit

Protection

Method

Current

limiting,

hiccup

autorestart.

Remove

overload for

recovery.

Short Circuit

16

Duration

Continuous,

output
shorted to
ground. No

damage.

(non-condensing)

to +85°C/85%

Relative

Humidity

DYNAMIC CHARACTERISTICS

Dynamic Load

Response

(50-75-50%

load step) to 1%

of fi nal value,

Model Family

μSec

(See note 1)

UCE-1.5/20-D48
UCE-1.8/30-D48
UCE-2.5/20-D48
UCE-3.3/15-D48
UCE-3.3/30-D48
UCE-5/10-D48
UCE-5/20-D48

100 max. 10 10 330

UCE-12/4.2-D48
UCE-12/8.3-D48

Start-up Time

IN to VOUT

V
regulated

(Max.)

100 50 50 480
150 10 10 400
100 50 50 350
200 50 50 480

50 15 10 380

100 50 50 400

30 60 60
50 50 50

Remote On/

Off to VOUT
regulated

mSec

(Max.)

Switching
Frequency

KHz

200

ABSOLUTE MAXIMUM RATINGS

Input Voltage:

Continuous:
48 Volt input models 75 Volts
Transient (100 mSec. Max.)
48 Volt input models 100 Volts

On/Off Control +15 Volts
Input Reverse Polarity Protection 5 Amps, 10 sec. max.
Output Overvoltage Protection Magnetic feedback.

See specifi cations.
Output Current Current-limited. Devices can

withstand sustained short circuit
without damage.

Storage Temperature –40 to +125°C.
Lead Temperature See soldering guidelines.

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.

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13 Nov 2009 MDC_UCE.A24_long Page 4 of 16

SPECIFICATIONS, CONTINUED

PERFORMANCE SPECIFICATION NOTES

(1) All models are tested and specifi ed with external 1||10 μF ceramic/tantalum output capaci­tors and no external input capacitor. All capacitors are low ESR types. These capacitors are
necessary to accommodate our test equipment and may not be required to achieve specifi ed
performance in your applications. All models are stable and regulate within spec under no-load
conditions.

General conditions for Specifi cations are +25 deg.C, VIN = nominal, VOUT = nominal, full load.
Adequate airfl ow must be supplied for extended testing under power.

(2) Input Ripple Current is tested and specifi ed over a 5 Hz to 20 MHz bandwidth. Input fi ltering

IN = 33 μF, 100V tantalum, CBUS = 220 μF, 100V electrolytic, LBUS = 12 μH.

is C
(3) Note that Maximum Power Derating curves indicate an average current at nominal input

voltage. At higher temperatures and/or lower airfl ow, the DC/DC converter will tolerate brief
full current outputs if the total RMS current over time does not exceed the Derating curve. All
Derating curves are presented at sea level altitude. Be aware of reduced power dissipation
with increasing density altitude.

(4) Mean Time Before Failure is calculated using the Telcordia (Belcore) SR-332 Method 1, Case
3, ground fi xed conditions, Tpcboard=+25 deg.C, full output load, natural air convection.

(5) The On/Off Control is normally controlled by a switch. But it may also be driven with exter­nal logic or by applying appropriate external voltages which are referenced to Input Common.
The On/Off Control Input should use either an open collector or open drain transistor.

(6) Short circuit shutdown begins when the output voltage degrades approximately 2% from
the selected setting.

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

(7) The outputs are not intended to sink appreciable reverse current. This may damage the
outputs.

(8) Output noise may be further reduced by adding an external fi lter. See I/O Filtering and Noise
Reduction.

(9) All models are fully operational and meet published specifi cations, including “cold start” at
–40ºC.

(10) Regulation specifi cations describe the deviation as the line input voltage or output load
current is varied from a nominal midpoint value to either extreme.

(11) Alternate pin length and/or other output voltages are available under special quantity order.
(12) Output overvoltage is non-latching. When the overvoltage fault is removed, the converter

will immediately recover.
(13) Do not exceed maximum power specifi cations when adjusting the output trim.
(14) At zero output current, the output may contain low frequency components which exceed

the ripple specifi cation. The output may be operated indefi nitely with no load.
(15) If reverse polarity is accidentally applied to the input, a body diode will become forward bi-

ased and will conduct considerable current. To ensure reverse input protection with full output
load, always connect an external input fuse in series with the +V

IN input.

PHYSICAL CHARACTERISTICS

Outline dimensions See mechanical specs (below)

Pin material Copper alloy

Pin diameter 0.04/0.062" (1.016/1.524mm)

Pin fi nish Nickel underplate with gold overplate

UCE-1.5/20-D48 0.67 ounces (19 grams)

UCE-1.8/30-D48,

UCE-2.5/20-D48

Weight

Electromagnetic interference (external fi lter required)

Safety Certifi ed to UL/cUL 60950-1, CSA-C22.2 No. 60950-1, IEC/EN 60950-1

UCE-5/10-D48

UCE-5/20-D48

UCE-12/4.2-D48

UCE-3.3/15-D48 1 ounce (28 grams)

UCE-3.3/30-D48, UCE-12/8.3-D48 0.81 ounces (23 grams)

0.71 ounces (20 grams)

Designed to meet EN55022/CISPR22 (requires external fi lter)

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 cations 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:
Maximum Preheat Temperature 115ºC.
Maximum Pot Temperature 270ºC.
Maximum Solder Dwell Time 7 seconds

For Sn/Pb based solders:
Maximum Preheat Temperature 105ºC.
Maximum Pot Temperature 250ºC.
Maximum Solder Dwell Time 6 seconds

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13 Nov 2009 MDC_UCE.A24_long Page 5 of 16

MECHANICAL SPECIFICATIONS

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

Open Frame

Without Baseplate

2.30 (58.4)

0.37 max
(9.4)

0.18
(4.6)

PINS 1-3, 5-7:

2.00 (50.8)

0.015 minimum clearance
between standoffs and

highest component

0.040±0.001 (1.016±0.025) dia.
PINS 4, 8:

0.062±0.001 (1.575±0.025) dia.

0.300
(7.62)

0.300
(7.62)

1

2

3

4

0.15

0.900

(3.81)

(22.9)

Pin 8

Bottom view

Standard pin length is shown. Please refer to the Part Number Structure
for special order pin lengths.

Dimensions are in inches (mm shown for ref. only).

Third Angle Projection

Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 2˚

Components are shown for reference only.

Please note that some
competitive units may use
different pin numbering or
alternate outline views. However,
all units are plug-compatible.

INPUT/OUTPUT CONNECTIONS

Pin Function P32

1 −Input
2 On/Off Control
3 +Input
4 −Output
5 −Sense
6 Output Trim
7 +Sense
8 +Output

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13 Nov 2009 MDC_UCE.A24_long Page 6 of 16

MECHANICAL SPECIFICATIONS

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

Screw length must not

go through baseplate.

0.50

(12.7)

0.300
(7.62)

0.300
(7.62)

1

2

3

0.00

(22.9)

With Baseplate

0.015 minimum clearance
between standoffs and
highest component

2.00 (50.8)

Bottom view

2.00 (50.8)

M3 threaded insert 2
places, See notes 1&2

PINS 1-3, 5-7:

0.040±0.001 (1.016±0.025) dia.
PINS 4, 8:

0.062±0.001 (1.575±0.025) dia.

0.18
(4.6)

4

0.15

0.900

(3.81)

(22.9)

Pin 8

0.600

(15.24)

Dimensions are in inches (mm shown for ref. only).

Third Angle Projection

Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 2˚

Components are shown for reference only.

Please note that some
competitive units may use
different pin numbering or
alternate outline views. However,
all units are plug-compatible.

INPUT/OUTPUT CONNECTIONS

Pin Function P32

1 −Input
2 On/Off Control
3 +Input
4 −Output
5 −Sense
6 Output Trim
7 +Sense
8 +Output

2.30 (58.4)

1. M3 screw used to bolt unit's baseplate to other surfaces (such as heatsink)
must not exceed 0.118'' (3mm) depth below the surface of baseplate

2. Applied torque per screw should not exceed 5.3 In-lb (0.6 Nm)

Standard pin length is shown. Please refer to the Part Number Structure
for special order pin lengths.

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13 Nov 2009 MDC_UCE.A24_long Page 7 of 16

APPLICATION NOTES

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 with a value which is approximately twice the maximum line
current, calculated at the lowest input voltage.

The installer must observe all relevant safety standards and regulations. For
safety agency approvals, install the converter in compliance with the end-user
safety standard, i.e. IEC/EN/UL 60950-1.

Input Reverse-Polarity Protection

If the input voltage polarity is reversed, an internal body diode will become
forward biased and likely draw excessive current from the power source. If this
source is not current-limited or the circuit appropriately fused, it could cause
permanent damage to the converter. Please be sure to install a properly-

rated external input fuse.

Input Under-Voltage Shutdown and Start-Up Threshold

Under normal start-up conditions, converters will not begin to regulate properly
until the ramping-up 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.

Users should be aware however of input sources near the Under-Voltage
Shutdown whose voltage decays as input current is consumed (such as
capacitor inputs), the converter shuts off and then restarts as the external
capacitor recharges. Such situations could oscillate. To prevent this, make
sure the operating input voltage is well above the UV Shutdown voltage AT ALL
TIMES.

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 ramping input voltage crosses the Start-Up Threshold and the fully loaded
regulated output voltage enters and remains within its specifi ed accuracy band.
Actual measured times will vary with input source impedance, external input
capacitance, 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 regulated
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.

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

Input Source Impedance

These converters will operate to specifi cations without external components,
assuming that the source voltage has very low impedance and reasonable
input voltage regulation. Since real-world voltage sources have fi nite imped­ance, performance is improved by adding external fi lter components. Some­times only a small ceramic capacitor is suffi cient. Since it is diffi cult to totally
characterize all applications, some experimentation may be needed. Note that
external input capacitors must accept high speed switching currents.

Because of the switching nature of DC/DC converters, the input of these
converters must be driven from a source with both low AC impedance and
adequate DC input regulation. Performance will degrade with increasing input
inductance. Excessive input inductance may inhibit operation. The DC input
regulation specifi es that the input voltage, once operating, must never degrade
below the Shut-Down Threshold under all load conditions. Be sure to use
adequate trace sizes and mount components close to the converter.

I/O Filtering, 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 compo­nents, circuits and layout as shown in the fi gures below. External input capaci­tors (Cin in the fi gure) serve primarily as energy storage elements, minimizing
line voltage variations caused by transient IR drops in the input conductors.
Users should select input capacitors for bulk capacitance (at appropriate
frequencies), low ESR and high RMS ripple current ratings. In the fi gure below,
the Cbus and Lbus components simulate a typical DC voltage bus. Your specifi c
system confi guration may require additional considerations. Please note that
the values of Cin, Lbus and Cbus will vary according to the specifi c converter
model.

TO

OSCILLOSCOPE

L

+

–

V

IN

+

–

CIN = 33μF, ESR < 700mΩ @ 100kHz

BUS

= 220μF, ESR < 100mΩ @ 100kHz

C

BUS

= 12μH

L

BUS

C

BUS

Figure 2. Measuring Input Ripple Current

In critical applications, output ripple and noise (also referred to as periodic
and random deviations or PARD) may be reduced by adding fi lter elements
such as multiple external capacitors. Be sure to calculate component tempera­ture rise from refl ected AC current dissipated inside capacitor ESR.

In the fi gure, the two copper strips simulate real-world printed circuit
impedances between the power supply and its load. In order to minimize circuit
errors and standardize tests between units, scope measurements should be
made using BNC connectors or the probe ground should not exceed one half
inch and soldered directly to the fi xture.

CURRENT

PROBE

C

IN

4

+INPUT

1

−INPUT

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13 Nov 2009 MDC_UCE.A24_long Page 8 of 16

6

+SENSE

+OUTPUT

−OUTPUT

−SENSE

C1 = 0.1μF CERAMIC
C2 = 10μF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE

Figure 3. Measuring Output Ripple and Noise (PARD)

5

9

8

COPPER STRIP

C1

COPPER STRIP

R

C2

SCOPE

LOAD

Floating Outputs

Since these are isolated DC/DC converters, their outputs are “fl oating” with
respect to their input. The essential feature of such isolation is ideal ZERO
CURRENT FLOW between input and output. Real-world converters however do
exhibit tiny leakage currents between input and output (see Specifi cations).
These leakages consist of both an AC stray capacitance coupling component
and a DC leakage resistance. When using the isolation feature, do not allow
the isolation voltage to exceed specifi cations. Otherwise the converter may
be damaged. Designers will normally use the negative output (-Output) as
the ground return of the load circuit. You can however use the positive output
(+Output) as the ground return to effectively reverse the output polarity.

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.

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/DC’s 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. The temperature sensor is typically
located adjacent to the switching controller, approximately in the center of the
unit. See the Performance and Functional Specifi cations.

CAUTION: If you operate too close to the thermal limits, the converter may
shut down suddenly without warning. Be sure to thoroughly test your applica­tion to avoid unplanned thermal shutdown.

Temperature Derating Curves

The graphs in the next section 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.

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

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 very low fl ow rates (below about 25 LFM) are similar to “natural
convection,” that is, not using fan-forced airfl ow.

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 routinely or accidentally exceed these Derating guidelines,
the converter may have an unplanned Over Temperature shut down. Also, these
graphs are all collected at slightly above Sea Level altitude. Be sure to reduce
the derating for higher density altitude.

Output Overvoltage Protection

This converter monitors its output voltage for an over-voltage condition. If
the output exceeds OVP limits, the sensing circuit will power down the unit,
and the output voltage will decrease. After a time-out period, the PWM will
automatically attempt to restart, causing the output voltage to ramp up to its
rated value. It is not necessary to power down and reset the converter for the
automatic OVP-recovery restart.

If the fault condition persists and the output voltage climbs to excessive
levels, the OVP circuitry will initiate another shutdown cycle. This on/off cycling
is referred to as “hiccup” mode. It safely tests full current rated output voltage
without damaging the converter.

Output Fusing

The converter is extensively protected against current, voltage and temperature
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

As soon as the output current increases to approximately 125% to 150% of
its maximum rated value, the DC/DC converter will enter a current-limiting
mode. The output voltage will decrease proportionally with increases in output
current, thereby maintaining a somewhat constant power output. This is also
commonly referred to as power 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 particularly 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 (approxi­mately 98% of nominal output voltage for most models), the magnetically

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coupled voltage used to develop primary side voltages will also drop, thereby
shutting down the PWM controller. Following a time-out period, the PWM will
restart, causing the output voltage to begin ramping up 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 current, 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 condi­tion is removed.

Remote Sense Input

Use the Sense inputs with caution. Sense is normally connected at the load.
Sense inputs compensate for output voltage inaccuracy delivered at the load.
This is done by correcting IR voltage drops along the output wiring and the
current carrying capacity of PC board etch. This output drop (the difference
between Sense and Vout when measured at the converter) should not be
allowed to exceed 0.5V. Consider using heavier wire if this drop is excessive.
Sense inputs also improve the stability of the converter and load system by
optimizing the control loop phase margin.

Note: The Sense input and power Vout lines are internally connected through
low value resistors to their respective polarities so that the converter can
operate without external connection to the Sense. Nevertheless, if the Sense
function is not used for remote regulation, the user should connect +Sense to
+Vout and –Sense to –Vout at the converter pins.

The remote Sense lines carry very little current. They are also capacitively
coupled to the output lines and therefore are in the feedback control loop to
regulate and stabilize the output. As such, they are not low impedance inputs
and must be treated with care in PC board layouts. Sense lines on the PCB
should run adjacent to DC signals, preferably Ground. In cables and discrete
wiring, use twisted pair, shielded tubing or similar techniques.

Any long, distributed wiring and/or signifi cant inductance introduced into the
Sense control loop can adversely affect overall system stability. If in doubt, test
your applications by observing the converter’s output transient response during
step loads. There should not be any appreciable ringing or oscillation. You
may also adjust the output trim slightly to compensate for voltage loss in any
external fi lter elements. Do not exceed maximum power ratings.

Please observe Sense inputs tolerance to avoid improper operation:

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

Contact and PCB resistance

losses due to IR drops

1

3

4

−

INPUT

ON/OFF
CONTROL

+INPUT

Figure 4. Remote Sense Circuit Confi guration

+OUTPUT

+SENSE

TRIM

−

SENSE

-OUTPUT

Trimming the Output Voltage

The Trim input to the converter allows the user to adjust the output voltage
over the rated trim range (please refer to the Specifi cations). In the trim equa­tions and circuit diagrams that follow, trim adjustments use either a trimpot or
a single fi xed resistor connected between the Trim input and either the +Sense
or –Sense terminals. (On some converters, an external user-supplied precision
DC voltage may also be used for trimming). Trimming resistors should have a
low temperature coeffi cient (±100 ppm/deg.C or less) and be mounted close
to the converter. Keep leads short. If the trim function is not used, leave the
trim unconnected. With no trim, the converter will exhibit its specifi ed output
voltage accuracy.

There are two CAUTIONs to be aware of for the Trim input:

CAUTION: To avoid unplanned power down cycles, do not exceed EITHER
the maximum output voltage OR the maximum output power when setting the
trim. Be particularly careful with a trimpot. If the output voltage is excessive,
the OVP circuit may inadvertantly shut down the converter. If the maximum
power is exceeded, the converter may enter current limiting. If the power is
exceeded for an extended period, the converter may overheat and encounter
overtemperature shut down.

CAUTION: Be careful of external electrical noise. The Trim input is a senstive
input to the converter’s feedback control loop. Excessive electrical noise may
cause instability or oscillation. Keep external connections short to the Trim
input. Use shielding if needed.

5

I OUT

6

Sense Current

7

Sense Return

8

I OUT Return

9

Contact and PCB resistance

losses due to IR drops

LOAD

[Vout(+) −Vout(-)] − [Sense(+) −Sense(-)] ≤ 10% of Vout

Output overvoltage protection is monitored at the output voltage pin, not the
Sense pin. Therefore excessive voltage differences between Vout and Sense
together with trim adjustment of the output can cause the overvoltage protec­tion circuit to activate and shut down the output.

Power derating of the converter is based on the combination of maximum
output current and the highest output voltage. Therefore the designer must
insure:

(Vout at pins) x (Iout)

≤ (Max. rated output power)

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Trim Equations

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

Trim Down

Connect trim resistor between

trim pin and −Sense

R

TrimDn

(k Ω) =

5.11



− 10.22

R

TrimUp

Connect trim resistor between

(k Ω) =

5.11 × VNOM × (1+)

Trim Up

trim pin and +Sense

1.225 × 

Where,

 = | (VNOM − VOUT) / VNOM |
VNOM is the nominal, untrimmed output voltage.
V

OUT is the desired new output voltage.

Do not exceed the specified trim range or maximum power ratings when adjusting trim.
Use 1% precision resistors mounted close to the converter on short leads.

Trim Circuits

–INPUT

ON/OFF
CONTROL

+OUTPUT

+SENSE

TRIM

LOAD

− 5.11



− 10.22

+VCC

3

ON/OFF

CONTROL

–SENSE

+INPUT

Figure 5. Trim Connections Using A Trimpot

–INPUT

ON/OFF
CONTROL

+INPUT

Connect sense to its respective VOUT pin if sense is not used with a remote load.

–OUTPUT

+OUTPUT

+SENSE

TRIM

–SENSE

–OUTPUT

TRIM UP

R

LOAD

1

-INPUT

Figure 7. Driving the On/Off Control Pin (suggested circuit)

–INPUT

ON/OFF
CONTROL

+INPUT

Figure 8. Trim Connections To Decrease Output VoltagesFigure 6. Trim Connections To Increase Output Voltages

+OUTPUT

+SENSE

TRIM

–SENSE

–OUTPUT

TRIM DOWN

R

LOAD

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13 Nov 2009 MDC_UCE.A24_long Page 11 of 16

Remote On/Off Control

On the input side, a remote On/Off Control can be ordered with either polarity.

Positive: Standard models are enabled when the On/Off pin is left open or
is pulled high to +Vin with respect to –Vin. An internal bias current causes
the open pin to rise to approximately +15V. Some models will also turn on at
lower intermediate voltages (see Specifi cations). Positive-polarity devices are
disabled when the On/Off is grounded or brought to within a low voltage (see
Specifi cations) with respect to –Vin.

Negative: Optional negative-polarity devices 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 approximately +15V with respect to –Vin.

Dynamic control of the On/Off function should be able to sink appropriate
signal current when brought low and withstand appropriate 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,
regulated output. This time will vary slightly with output load type and current
and input conditions.

On/Off Enable Control Ground Bounce Protection

To improve reliability, if you use a small signal transistor or other external
circuit to select the Remote On/Off control, make sure to return the LO side
directly to the –Vin power input on the DC/DC converter. To avoid ground
bounce errors, do not connect the On/Off return to a distant ground plane or
current-carrying bus. If necessary, run a separate small return wire directly to
the –Vin terminal. There is very little current (typically 1-5 mA) on the On/Off
control however, large current changes on a return ground plane or ground bus
can accidentally trigger the converter on or off. If possible, mount the On/Off
transistor or other control circuit adjacent to the converter.

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

There are several CAUTIONs for the On/Off Control:

CAUTION: While it is possible to control the On/Off with external logic if
you carefully observe the voltage levels, the preferred circuit is either an open
drain/open collector transistor, a switch or a relay (which can thereupon be
controlled by logic) returned to negative Vin.

CAUTION: Do not apply voltages to the On/Off pin when there is no input
power voltage. Otherwise the converter may be permanently damaged.

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 step loads. Install only enough capaci­tance to achieve noise objectives. Excess external capacitance may cause
regulation problems, slower transient response and possible instability. Proper
wiring of the Sense inputs will improve these factors under capacitive load.

The maximum rated output capacitance and ESR specifi cation is given for a
capacitor installed immediately adjacent to the converter. Any extended output
wiring or smaller wire gauge or less ground plane may tolerate somewhat higher
capacitance. Also, capacitors with higher ESR may use a larger capacitance.

On/Off
Control
Transistor

Do not connect
control transistor
through remote
power bus

DC/DC Converter

Preferred location
of On/Off control
adjacent to -Vin
terminal

Ground plane or power return bus

Figure 9. On/Off Enable Control Ground Bounce Protection

Install separate
return wire for
On/Off control
with remote
transistor

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+ Vin

On/Off Enable

-Vin return

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13 Nov 2009 MDC_UCE.A24_long Page 12 of 16

Typical Performance Curves

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

UCE-1.5/20-D48 Efficiency vs Line Voltage & Load Current @ 25ºC

90

85

80

75

Efficiency (%)

70

65

60

3 6 9 12 15 18

UCE-1.8/30-D48 Efficiency vs Line Voltage & Load Current @ 25ºC
95
90
85
80
75
70
65

Efficiency (%)

60
55
50
45
40

3 5 7 9 11 13 15 17 19 21 23 25 27 29

Vin = 75V

Vin = 48V

Vin = 36V

Vin = 75V

Vin = 48V

Vin = 36V

Load Current (A)

Load Current (A)

UCE-1.5/20-D48 Maximum Current Temperature Derating
(Vin = 48V, no baseplate, longitudinal airflow at sea level)

20

16

12

8

Output Current (A)

4

0

30 35 40 45 50 55 60 65 70 75 80 85

Ambient Temperature (ºC)

UCE-1.8/30-D48 Maximum Current Temperature Derating

(Vin = 48V, no baseplate, longitudinal airflow at sea level)

35

30

25

20

15

Output Current (A)

10

5

0

30 35 40 45 50 55 60 65 70 75 80

400 LFM
300 LFM
200 LFM
100 LFM

Ambient Temperature (ºC)

400 LFM
300 LFM
200 LFM
100 LFM

UCE-2.5/20-D48 Efficiency vs Line Voltage & Load Current @ 25ºC

95

90

85

Efficiency (%)

80

75

70

3 4 5 6 7 8 9 1011121314151617181920

Vin = 75V
Vin = 48V
Vin = 36V

Load Current (A)

UCE-2.5/20-D48 Maximum Current Temperature Derating

(Vin = 48V, with baseplate, longitudinal airflow at sea level)

20

18

16

14

12

Output Current (A)

10

30 40 50 60 70 80

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300 LFM
200 LFM
100 LFM

Natural Convection

Ambient Temperature (ºC)

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13 Nov 2009 MDC_UCE.A24_long Page 13 of 16

Typical Performance Curves

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

UCE-3.3/15-D48 Efficiency Vs. Line Voltage & Load Current @ +25ºC

95

90

85

80

Efficiency (%)

75

70

3 4 5 6 7 8 9 10 11 12 13 14 15

UCE-3.3/30-D48 Efficiency vs Line Voltage & Load Current @ 25ºC

95

90

85

80

75

70

65

Efficiency (%)

60

55

50

45

40

3 4 5 6 7 8 9 101112131415161718192021 222324252627282930

Vin = 75V
Vin = 48V
Vin = 36V

Load Current (A)

Vin = 75V
Vin = 48V
Vin = 36V

Load Current (A)

UCE-3.3/15-D48 Maximum Current Temperature Derating
(Vin = 48V, no baseplate, longitudinal airflow at sea level)

15

12

9

6

Output Current (A)

3

0

30 35 40 45 50 55 60 65 70 75 80 85

Ambient Temperature (ºC)

UCE-3.3/30-D48 Maximum Current Temperature Derating

(Vin = 48V, no baseplate, longitudinal airflow at sea level)

35

30

25

20

15

Output Current (A)

10

5

0

30 35 40 45 50 55 60 65 70 75 80

400 LFM
300 LFM
200 LFM

100 LFM

Ambient Temperature (ºC)

400 LFM
300 LFM
200 LFM
100 LFM

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13 Nov 2009 MDC_UCE.A24_long Page 14 of 16

Typical Performance Curves

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

UCE-5/10-D48 Efficiency Vs. Line Voltage & Load Current @ +25ºC

100

98
96
94
92
90
88
86
84
82

Efficiency (%)

80
78
76
74
72
70

12345678 910

Vin = 75V
Vin = 48V
Vin = 36V

Power Dissipation (Vin = 48V)

Load Current (A)

UCE-5/20-D48 Efficiency Vs. Line Voltage & Load Current @ +25ºC

96

94

92

90

88

86

Efficiency (%)

84

82

80

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Vin = 75V
Vin = 48V
Vin = 36V

Power Dissipation (Vin = 48V)

Load Current (A)

3.5

3

2.5

2

1.5

1

Power Dissipation (Watts)

0.5

0

16

14

12

10

8

6

4

Power Dissipation (Watts)

2

0

UCE-5/10-D48 Maximum Current Temperature Derating at Sea Level

(Vin = 48V, transverse airflow, no baseplate)

11

10

9

8

7

6

Output Current (A)

5

4

30 35 40 45 50 55 60 65 70 75 80 85

UCE-5/20-D48 Maximum Current Temperature Derating at Sea Level

(Vin = 48V, transverse airflow, no baseplate)

25

20

15

10

Output Current (A)

5

0

30 35 40 45 50 55 60 65 70 75 80 85

Natural Convection

100 LFM
200 LFM
300 LFM
400 LFM

Ambient Temperature (ºC)

Natural Convection

100 LFM
200 LFM
300 LFM
400 LFM

Ambient Temperature (ºC)

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13 Nov 2009 MDC_UCE.A24_long Page 15 of 16

Typical Performance Curves

Ambient Temperature (ºC)

Output Current (A)

60

65

70

75

80

85

90

95

0.6 1.2 1.8 2.4 3.0 3.6 4.2

UCE Series

Isolated, High-Density, Eighth-Brick

100W DC/DC Converters

UCE-12/4.2-D48 Efficiency Vs. Line Voltage & Load Current @ +25ºC

Vin = 75V

Vin = 48V

Efficiency (%)

UCE-12/8.3-D48 Efficiency vs Line Voltage & Load Current @ 25ºC

95

90

85

80

Efficiency (%)

75

70

345678

Vin = 36V

Load Current (A)

Vin = 75V
Vin = 48V
Vin = 36V

Load Current (A)

UCE-12/4.2-D48 Maximum Current Temperature Derating

(Vin = 48V, no baseplate, longitudinal airflow at sea level)

4.25

4

3.75

3.5

3.25

3

30 40 50 60 70 80

UCE-12/8.3-D48 Maximum Current Temperature Derating

(Vin = 48V, no baseplate, longitudinal airflow at sea level)

9

8

7

6

5

4

3

Output Current (A)

2

1

0

30 35 40 45 50 55 60 65 70 75 80 85

400 LFM
300 LFM
200 LFM
100 LFM

200 to 400 LFM

100 LFM

Ambient Temperature (ºC)

UCE-12/8.3-D48 Maximum Current Temperature Derating at sea level

(Vin = 48V, with baseplate, airflow is from -Vin to +Vin)

9

8

7

6

5

4

3

Output Current (A)

2

1

0

30 35 40 45 50 55 60 65 70 75 80 85

Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 U.S.A.

ISO 9001 and 14001 REGISTERED

400 LFM
300 LFM
200 LFM
100 LFM

Ambient Temperature (ºC)

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. © 2009 Murata Power Solutions, Inc.

www.murata-ps.com/locations email: [email protected]

13 Nov 2009 MDC_UCE.A24_long Page 16 of 16