MURATA ULS-12/5-D48N-C

ULS Series
www.murata-ps.com
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
FEATURES
„
Small footprint DC/DC converter, ideal for
high current applications
„
Tiny 0.9" x 1.3" x 0.40" open frame package
Typical unit
„
Industry standard DOSA "brick" format
and pinout
„
36-75 Volts DC input range
PRODUCT OVERVIEW
„
2250 Volt Basic input/output isolation
(48V models)
The world of “brick” DC/DC converters has seen
a steady size reduction. The ULS series makes
another dramatic size shrink down to a “sixteenthbrick” width (0.9 inches) while still retaining a
66 Watt output and full 2250 Volt DC isolation.
The PC-board mount converter family accepts
36 to 75 Volts DC inputs and delivers fixed outputs
regulated to within ±0.2%. The ULS converters
are ideal for datacom and telecom applications,
cell phone towers, data centers, server farms and
network repeaters.
ULS outputs may be trimmed within ±10% of
nominal output while delivering fast settling to
current step loads and no adverse effects from
higher capacitive loads. Excellent ripple and noise
specifications assure compatibility to circuits using
CPU’s, ASIC’s, programmable logic and FPGA’s. No
„
Up to 66 Watts total output power with
overtemperature shutdown
„
High efficiency synchronous rectifier forward
topology
„
Stable no-load operation with no required
external components
„
Operating temperature range -40 to +85°C
with derating
„
UL 60950-1, CSA-C22.2 No. 234,
EN60950-1 safety approvals, 2nd Edition
(pending)
„
Extensive self-protection shut down features
minimum load is required. For systems requiring
controlled startup/shutdown, an external remote
On/Off control may use a switch, transistor or digital
logic. Remote Sense inputs compensate for resistive line drops at high currents.
Many self-protection features on the ULS series
avoid both converter and external circuit hazards.
These include input undervoltage lockout and
overtemperature shutdown. The outputs current
limit using the “hiccup” autorestart technique and
the outputs may be short-circuited indefinitely.
Additional features include output overvoltage and
reverse conduction elimination.
The synchronous rectifier forward topology yields
high efficiency for minimal heat buildup and “no
fan” operation.
SIMPLIFIED BLOCK DIAGRAM
+SENSE
(7)
+Vin
(1)
+Vout
(8)
SWITCH
CONTROL
-Vout
(4)
-Vin
(3)
INPUT
UNDER VOLTAGE,
OVER TEMPERATURE,
AND OUTPUT
OVER VOLTAGE
COMPARATORS
PULSE
TRANSFORMER
PWM
CONTROLLER
OPTO
ISOLATION
-SENSE
(5)
REFERENCE
ERROR AMP
Vout
TRIM
(6)
REMOTE
ON/OFF
CONTROL
(2)
Typical topology is shown
Figure 1. Simplified Block Diagram
For full details go to
www.murata-ps.com/rohs
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19 Jul 2010
MDC_ULS Series.B16 Page 1 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
PERFORMANCE SPECIFICATIONS AND ORDERING GUIDE M
Output
Input
Root Model M
VOUT
(V)
Typ.
Max.
ULS-3.3/20-D48N-C
3.3
20
66
70
120
±0.1%
±0.2%
48
ULS-5/12-D48N-C
5
12
60
50
80
±0.125%
±0.25%
ULS-12/5-D48N-C
12
5
60
80
120
±0.125%
±0.25%
ULS-15/2-D48N-C
15
2
ULS-12/2.5-D48N-C
12
2.5
Power
IOUT
(A, max.) (W)
R/N (mV pk-pk) N
Regulation (max.) P VIN Nom. Range
(V)
(V)
Line
Load
C76
Package
Efficiency
IIN, no load
(mA)
IIN, full
load (A)
Min.
Typ.
Case (inches)
36-75
20
1.53
89%
90%
0.9x1.3x0.40
48
36-75
40
1.39
88%
90%
0.9x1.3x0.40
48
36-75
50
1.37
88%
91%
0.9x1.3x0.40
0.9x1.3x0.40
PRELIMINARY – Please contact Murata Power Solutions for further information.
0.9x1.3x0.40
M Please refer to the Part Number Structure when ordering.
➃ Regulation specifications describe output voltage deviations from a nominal/midpoint value to either
N These specifications are preliminary. Contact Murata Power Solutions for availability.
extreme (50% load step).
O All specifications are at nominal line voltage and full load, +25°C unless otherwise noted. See detailed ➄ Models ULS-12/2.5-D48N-C and ULS-15/2-D48N-C do not include sense pins.
specifications. Output capacitors are 1 μF ceramic multilayer in parallel with 10 μF electrolytic.
I/O caps are necessary for our test equipment and may not be needed for your application.
PART NUMBER STRUCTURE
ULS - 3.3 / 20 - D48 N H Lx - C
RoHS Hazardous Substance Compliance
(does not claim EU RoHS exemption 7b–lead in solder)
C = RoHS-6
Y = RoHS-5
Sixteenth Brick Series
Pin Length Option (Thru-hole only)
Blank = Standard pin length 0.180˝ (4.6mm)
L1 = 0.110˝ (2.79mm)
L2 = 0.145˝ (3.68mm)
Nominal Output Voltage:
Conformal Coating:
Blank = No coating, standard
H = Coating added, optional special order
Maximum Rated Output Current
Current in Amps
Input Voltage Range:
D48 = 36-75 Volts (48V nominal)
On/Off Control Polarity:
N = Negative, standard
P = Positive, optional special order
Note:
Some model number combinations
may not be available. Contact Murata
Power Solutions.
DC/DC Converter
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.
+ Vin
Preferred location
of On/Off control
adjacent to -Vin
terminal
On/Off Enable
On/Off
Control
Transistor
-Vin return
Ground plane or power return bus
Do not connect
control transistor
through remote
power bus
Install separate
return wire for
On/Off control
with remote
transistor
Figure 2. On/Off Enable Control Ground Bounce Protection
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19 Jul 2010
MDC_ULS Series.B16 Page 2 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
MECHANICAL SPECIFICATIONS
BOTTOM PIN SIDE VIEW
1.30
3
2
6
0.300
0.600
0.90
5
0.600
END VIEW
4
7
Important! Always connect the sense pins. If they
are not connected to a remote load, wire each
sense pin to its respective voltage output at the
converter pins.
* Models ULS-12/2.5-D48N-C and ULS-15/2-D48N-C do
0.136 ±0.005
0.030 Min
INPUT/OUTPUT CONNECTIONS P75
Pin
Function
Pin
Function
3 Negative Input 4
Negative Output
5
–Sense In*
2 On/Off Control 6
Trim
7
+Sense In*
1 Positive Input 8
Positive Output
0.145 0.400 Max
8
1
SIDE VIEW
PINS 1-3,5-7:
φ0.040±0.001(1.016±0.025)
PINS 4,8:
φ0.062±0.001(1.575±0.025)
1.100
not include sense pins.
The 0.145-inch pin length is shown. Please refer to the
part number structure for alternate pin lengths.
Pin material: Copper alloy. Plating: Gold over nickel
Dimensions are in inches (mm) shown for ref. only.
TOP VIEW
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
and may vary between units.
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19 Jul 2010
MDC_ULS Series.B16 Page 3 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
Absolute Maximum Ratings
Input Voltage
Continuous
+75 Volts
Transient (100 mS)
+100 Volts
On/Off Control
0 V. min to +15 V. max.
Input Reverse Polarity Protection
None, install external fuse
Current-limited. Devices can withstand
Output Current
sustained short circuit without damage.
Storage Temperature
–55 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 Specifications
Table is not implied or recommended.
Performance/Functional Specifications
Typical at TA = +25°C under nominal line voltage, nominal output voltage, natural air
convection, 1 μF || 10 μF output external caps, 22μF low ESR input external cap and
full-load conditions unless otherwise noted.(1)
Input Voltage Range
Start-up Threshold
Undervoltage Shutdown (12)
Overvoltage Shutdown
Reflected (Back) Ripple Current (2)
Input Current
Full Load Conditions
Inrush Transient
Output Short Circuit Current
Low Line (VIN = Vmin.)
Standby Mode(Off, UV, OT shutdown)
Internal Input Filter Type
Recommended External
Fast Blow Fuse
Reverse Polarity Protection
Remote On/Off Control (6)
Positive Logic ("P" model suffix)
Negative Logic ("N" model suffix)
Current, mA
Out
Voltage Output Range (3)(15)
Voltage Output Accuracy
Adjustment Range (8)
Temperature Coefficient
Minimum Loading
Remote Sense Compensation
Ripple/Noise (20 MHz bandwidth)
Line/Load Regulation (7)
Input
See Ordering Guide
34.5 Volts (ULS-3.3 & -5)
33.5 Volts (ULS-12/2.5)
32.5 Volts
None
20 mA pk-pk
See Ordering Guide
0.05 A2Sec.
100 mA
2.08 Amps (ULS-3.3/20-D48)
1.85 Amps (ULS-5/12-D48)
1.83 Amps (ULS-12/5-D48)
0.95 Amps (ULS-12/2.5)
Output, continued
Efficiency
See Ordering Guide
Maximum Capacitive Loading (Low 1000μF max. (ULS-3.3 &-5)
ESR > 0.02 Ω min., resistive load)
2000μF (ULS-12/2.5)
Isolation Voltage
2250 Vdc min.
Input to Output
Isolation Resistance
10 Megohms min.
Isolation Capacitance
1000 pF
Isolation Safety Rating
Basic insulation
Current Limit Inception (13)
26 Amps (ULS-3.3/20-D48, ULS-5/12-D48)
(97% of VOUT setting, after warmup) 6.8 Amps (ULS-12/5-D48)
3.5 Amps (ULS-12/2.5)
Short Circuit (5)
Current limiting with hiccup autorestart.
Protection Method
Remove overload for recovery.
Short Circuit Current
6.6 Amps (ULS-3.3/20-D48)
0.5 Amps (ULS-5/12-D48)
0.6 Amps (ULS-12/5-D48)
0.04 Amps (ULS-12/2.5)
Continuous, output shorted to ground (no
Short Circuit Duration
damage)
Overvoltage Protection
4.29 Volts (ULS-3.3/20-D48)
via Magnetic feedback
6.5 Volts (ULS-5/12-D48)
14.5 Volts (ULS-12/5-D48)
15 Volts (ULS-12/2.5)
150 μSec to ±1% of final value
Dynamic Load Response
(ULS-3.3/20-D48)
25-50-25 μSec to ±1% of final value
(ULS-5/12-D48, ULS-12/5-D48)
Start-Up Time
5 mSec (ULS-3.3/20-D48)
10 mSec (ULS-5/12-D48)
VIN on to VOUT regulated
30 mSec (ULS-12/5-D48)
Remote On/Off to VOUT regulated
30 mSec (ULS-12/5-D48)
Switching Frequency
400-520 kHz (ULS-3.3 & -5)
260-310 kHz (ULS-12/2.5)
The converter will start if the external load
Pre-Bias Load Startup
pre-bias does not exceed Vnominal
Environmental
Calculated MTBF(4)
3.2M Hours
Operating Temperature Range
–40 to +85°C(11)
With derating
See Derating Curves
Storage Temperature Range
–55 to +125°C
Thermal Protection/Shutdown
+110-130°C (hot spot)
Relative Humidity (non-condensing) to +85%RH/+85°C
Physical
Outline Dimensions
See Mechanical Specifications
Gold-plated copper alloy with nickel
Pin Material
underplate
Pin Diameter
(Pins 1-3, 5-7)
0.04" (1.02mm)
(Pins 4 & 8)
0.062" (1.58mm)
Weight
0.58 ounce (16.4 grams)
Electromagnetic Interference
EN55022/CISPR22 (requires external filter)
(50-75% load step)
5 mA
Capacitive
10 Amps (ULS-3.5 & -5)
2 Amps (ULS-12/2.5)
None, install external fuse
Off = ground pin to +1.0 V Max
On = open pin or + 10 V min. to +15 V Max
Off = open pin or +2.5 V min. to +15 V Max
On = -0.1 V to +0.8 V Max
1-5
Output
See Ordering Guide
±1% of Vnominal
-10% to +10% of Vnominal (ULS-3.3 &-5)
-20% to +10% (ULS-12/2.5)
±0.02% of Vout range per °C
No minimum load
10% max. of Vset (18)
See Ordering Guide (9)(14)
See Ordering Guide
Safety (designed to meet)
UL/cUL 60950-1, CSA-C22.2 No.234,
IEC/EN 60950-1, 2nd Edition
Flammability Rating
UL94V-0 (designed to meet)
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19 Jul 2010
MDC_ULS Series.B16 Page 4 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
Performance Specification Notes
1. All specifications are typical unless noted. Ambient temperature =
+25°Celsius, VIN is nominal, output current is maximum rated nominal.
External output capacitance is 1 μF multilayer ceramic paralleled with
10 μF electrolytic. All caps are low ESR. These capacitors are necessary for
our test equipment and may not be needed in your application.
Testing must be kept short enough that the converter does not appreciably
heat up during testing. For extended testing, use plenty of airflow. See
Derating Curves for temperature performance. All models are stable and
regulate within spec without external cacacitance.
2. Input Ripple Current is tested and specified over a 5-20 MHz bandwidth
and uses a special set of external filters only for the Ripple Current specifications. Input filtering is CIN = 33 μF, CBUS = 220 μF, LBUS = 12 μH. Use
capacitor rated voltages which are twice the maximum expected voltage.
Capacitors must accept high speed AC switching currents.
3. Note that Maximum Current Derating Curves indicate an average current
at nominal input voltage. At higher temperatures and/or lower airflow, the
converter will tolerate brief full current outputs if the average 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.
8. Do not exceed maximum power ratings, Sense limits or output overvoltage
when adjusting output trim values.
9. At zero output current, Vout may contain components which slightly
exceed the ripple and noise specifications.
10. Output overload protection is non-latching. When the output overload
is removed, the output will automatically recover.
11. All models are fully operational and meet published specifications,
including “cold start” at –40°C.
12. The converter will shut off if the input falls below the undervoltage threshold. It will not restart until the input exceeds the Input Start Up Voltage.
13. Short circuit shutdown begins when the output voltage degrades approximately 2% from the selected setting.
14. Output noise may be further reduced by installing an external filter. See
the Application Notes. Use only as much output filtering as needed and no
more. Larger caps (especially low-ESR ceramic types) may slow transient
response or degrade dynamic performance. Thoroughly test your application with all components installed.
15. To avoid damage or unplanned shutdown, do not sink appreciable reverse
output current.
4. Mean Time Before Failure (MTBF) is calculated using the Telcordia
(Belcore) SR-332 Method 1, Case 3, Issue 1, ground fixed conditions. Operating temperature = +30°C, full output load, natural air convection.
16. If reverse polarity is accidentally applied to the input, to ensure reverse
input protection with full output load, always connect an external fast blow
input fuse in series with the +VIN input.
5. The output may be shorted to ground indefinitely with no damage. The
Output Short Circuit Current shown in the specifications is an average consisting of very short bursts of full rated current to test whether the output
circuit can be repowered.
17. Although extremely unlikely, failure of the internal components of this
product may expose external application circuits to dangerous voltages,
currents, temperatures or power levels. Please thoroughly verify all applications before committing them to service. Be sure to include appropriately-rated FUSES (see specifications and Application Notes) to reduce the
risk of failure.
6. The On/Off Control is normally driven from a switch or relay. An open
collector/open drain transistor may be used in saturation and cut-off
(pinch-off) modes. External logic may also be used if voltage levels are
fully compliant to the specifications.
18. Models ULS-12/2.5-D48 and ULS-15/2-D48 do not include sense pins.
7. Regulation specifications describe the deviation as the input line voltage
or output load current is varied from a nominal midpoint value to either
extreme (50% load).
Soldering Guidelines
Murata Power Solutions recommends the specifications below when installing these converters. These specifications vary depending on the solder type. Exceeding these specifications 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
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19 Jul 2010
MDC_ULS Series.B16 Page 5 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
Input Fusing
Certain applications and/or safety agencies may require the installation of
fuses at the inputs of power conversion components. Fuses should also be
used if the possibility of sustained, non-current-limited, input-voltage polarity
reversals exists. For DATEL ULS series DC/DC converters, we recommend the
use of a fast blow fuse, installed in the ungrounded input supply line with a
typical value about twice the maximum input current, calculated at low line
with the converter’s minimum efficiency.
All relevant national and international safety standards and regulations must
be observed by the installer. For system safety agency approvals, the converters must be installed in compliance with the requirements of the end- use
safety standard, i.e. IEC/EN/UL60950-1.
Input Reverse-Polarity Protection
If the input voltage polarity is accidentally reversed, an internal 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.
I/O Filtering, Input Ripple Current, and Output Noise
All models in the ULS Series are tested/specified for input reflected ripple
current and output noise using the specified external input/output components/
circuits and layout as shown in the following two figures. External input capacitors (CIN in Figure 3) serve primarily as energy-storage elements, minimizing line voltage variations caused by transient IR drops in conductors from
backplane to the DC/DC. Input caps should be selected for bulk capacitance
(at appropriate frequencies), low ESR, and high rms-ripple-current ratings. The
switching nature of DC/DC converters requires that dc voltage sources have
low ac impedance as highly inductive source impedance can affect system stability. In Figure 3, CBUS and LBUS simulate a typical dc voltage bus. Your specific
system configuration may necessitate additional considerations.
TO
OSCILLOSCOPE
CURRENT
PROBE
+INPUT
LBUS
+
VIN
CBUS
CIN
–
Input Under-Voltage Shutdown and Start-Up Threshold
Under normal start-up conditions, devices will not begin to regulate properly
until the ramping-up input voltage exceeds the Start-Up Threshold Voltage.
Once operating, devices will not turn off until the input voltage drops below the
Under-Voltage Shutdown limit. Subsequent re-start will not occur until the input
is brought back up to the Start-Up Threshold. This built in hysteresis prevents
any unstable on/off situations from occurring at a single input voltage.
Start-Up Time
The VIN to VOUT Start-Up Time is the time interval between the point at which
the ramping input voltage crosses the Start-Up Threshold and the fully loaded
output voltage enters and remains within its specified accuracy band. Actual
measured times will vary with input source impedance, external input capacitance, and the slew rate and final value of the input voltage as it appears at the
converter. The ULS Series implements a soft start circuit to limit the duty cycle
of its PWM controller at power up, thereby limiting the input inrush current.
The On/Off Control to VOUT start-up time assumes the converter has its
nominal input voltage applied but is turned off via the On/Off Control pin. The
specification defines the interval between the point at which the converter is
turned on (released) and the fully loaded output voltage enters and remains
within its specified accuracy band. Similar to the VIN to VOUT start-up, the On/Off
Control to VOUT start-up time is also governed by the internal soft start circuitry
and external load capacitance. The difference in start up time from VIN to VOUT
and from On/Off Control to VOUT is therefore insignificant.
Input Source Impedance
The input of ULS converters must be driven from a low ac-impedance source.
The DC/DC’s performance and stability can be compromised by the use of
highly inductive source impedances. The input circuit shown in Figure 3 is a
practical solution that can be used to minimize the effects of inductance in the
input traces. For optimum performance, components should be mounted close
to the DC/DC converter.
–INPUT
CIN = 33μF, ESR < 700m7 @ 100kHz
CBUS = 220μF, ESR < 100m7 @ 100kHz
LBUS = 12μH
Figure 3. Measuring Input Ripple Current
In critical applications, output ripple/noise (also referred to as periodic and
random deviations or PARD) may be reduced below specified limits using filtering techniques, the simplest of which is the installation of additional external
output capacitors. They function as true filter elements and should be selected
for bulk capacitance, low ESR and appropriate frequency response.
All external capacitors should have appropriate voltage ratings and be
located as close to the converter as possible. Temperature variations for all
relevant parameters should also be taken carefully into consideration. The most
effective combination of external I/O capacitors will be a function of line voltage
and source impedance, as well as particular load and layout conditions.
In Figure 4, the two copper strips simulate real-world PCB impedances
between the power supply and its load. In order to minimize measurement
errors, scope measurements should be made using BNC connectors, or the
probe ground should be less than ½ inch and soldered directly to the fixture.
Floating Outputs
Since these are isolated DC/DC converters, their outputs are “floating” with
respect to their input. Designers will normally use the –Output as the ground/
return of the load circuit. You can however, use the +Output as ground/return to
effectively reverse the output polarity.
Minimum Output Loading Requirements
ULS converters employ a synchronous-rectifier design topology and all models
regulate within spec and are stable under no-load to full load conditions.
Operation under no-load conditions however might slightly increase the output
ripple and noise.
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19 Jul 2010
MDC_ULS Series.B16 Page 6 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
+SENSE
COPPER STRIP
+OUTPUT
C1
C2
SCOPE
RLOAD
–OUTPUT
–SENSE
COPPER STRIP
C1 = 1μF CERAMIC
C2 = 10μF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE
Remote Sense
Note: The Sense and VOUT lines are internally connected through low-value
resistors. Nevertheless, if the sense function is not used for remote regulation
the user should connect the +Sense to +VOUT and –Sense to –VOUT at the DC/
DC converter pins. ULS series converters employ a sense feature to provide
point of use regulation, thereby overcoming moderate IR drops in PCB conductors or cabling. The remote sense lines carry very little current and therefore
require minimal cross-sectional-area conductors. The sense lines, which are
capacitively coupled to their respective output lines, are used by the feedback
control-loop to regulate the output. As such, they are not low impedance points
and must be treated with care in layouts and cabling. Sense lines on a PCB
should be run adjacent to dc signals, preferably ground.
[VOUT(+)-VOUT(–)] – [Sense(+)-Sense(–)] d 10%VOUT
Figure 4. Measuring Output Ripple/Noise (PARD)
Thermal Shutdown
The ULS converters are equipped with thermal-shutdown circuitry. If environmental conditions cause the temperature of the DC/DC converter to rise above
the designed operating temperature, a precision temperature sensor will power
down the unit. When the internal temperature decreases below the threshold
of the temperature sensor, the unit will self start. See Performance/Functional
Specifications.
Output Over-Voltage Protection
The ULS output voltage is monitored for an over-voltage condition using a comparator. The signal is optically coupled to the primary side and if the output voltage rises to a level which could be damaging to the load, the sensing circuitry
will power down the PWM controller causing the output voltage to decrease.
Following a time-out period the PWM will restart, causing the output voltage
to ramp to its appropriate value. If the fault condition persists, and the output
voltage again climbs to excessive levels, the over-voltage circuitry will initiate
another shutdown cycle. This on/off cycling is referred to as “hiccup” mode.
In cables and discrete wiring applications, twisted pair or other techniques
should be used. Output over-voltage protection is monitored at the output voltage pin, not the Sense pin. Therefore, excessive voltage differences between
VOUT and Sense in conjunction with trim adjustment of the output voltage can
cause the over-voltage protection circuitry to activate (see Performance Specifications for over-voltage limits). Power derating is based on maximum output
current and voltage at the converter’s output pins. Use of trim and sense functions can cause output voltages to increase, thereby increasing output power
beyond the converter’s specified rating, or cause output voltages to climb into
the output over-voltage region. Therefore, the designer must ensure:
(VOUT at pins) x (IOUT) d rated output power
Contact and PCB resistance
losses due to IR drops
–INPUT
+OUTPUT
IOUT
+SENSE
Current Limiting
As soon as the output current increases to approximately 130% of its rated
value, the DC/DC converter will go into a current-limiting mode. In this condition, the output voltage will decrease proportionately with increases in output
current, thereby maintaining somewhat constant power dissipation. This is
commonly referred to as power limiting. Current limit inception is defined
as the point at which the full-power output voltage falls below the specified
tolerance. See Performance/Functional Specifications. If the load current, being
drawn from the converter, is significant enough, the unit will go into a short
circuit condition as described below.
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, the magnetically 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 to their appropriate value. If the short-circuit condition persists, another shutdown cycle will be
initiated. This on/off cycling is referred to as “hiccup” mode. The hiccup cycling
reduces the average output current, thereby preventing internal temperatures
from rising to excessive levels. The ULS Series is capable of enduring an indefinite short circuit output condition.
Sense Current
ON/OFF
CONTROL
TRIM
LOAD
Sense Return
–SENSE
IOUT Return
+INPUT
–OUTPUT
Contact and PCB resistance
losses due to IR drops
Figure 5. Remote Sense Circuit Configuration
On/Off Control
The input-side, remote On/Off Control function can be ordered to operate with
either polarity:
Positive ("P" suffix) polarity models are enabled when the on/off pin is left
open (or is pulled high, applying +3.5V to +13.5V with respect to –Input) as per
Figure 6. Positive-polarity devices are disabled when the on/off pin is pulled
low (0 to 0.8V with respect to –Input).
Negative (“N” suffix) polarity devices are off when pin is left open (or pulled
high, applying +3.5V to +13.5V), and on when pin is pulled low (0 to 1V) with
respect to –Input as shown in Figure 10.
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MDC_ULS Series.B16 Page 7 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
Dynamic control of the remote on/off function is best accomplished with a
mechanical relay or an open-collector/open-drain drive circuit (optically isolated
if appropriate). The drive circuit should be able to sink appropriate current (see
Performance Specifications) when activated and withstand appropriate voltage
when deactivated. Applying an external voltage to pin 2 when no input power is
applied to the converter can cause permanent damage to the converter.
+INPUT
+Vcc
13V CIRCUIT
ON/OFF
CONTROL
5V CIRCUIT
–INPUT
Figure 6. Driving the Negative Polarity On/Off Control Pin
(simplified circuit)
OUTPUT VOLTAGE ADJUSTMENT
Trim Equations
–INPUT
Trim Down
RT DOWN (k:) =
5.11
Δ
– 10.22
+SENSE
VOUT – VNOM
Where Δ _ _
VNOM
ON/OFF
CONTROL
Trim Up
RT UP (k:) =
5.11 × VNOM x (1 + Δ)
1.225 × Δ
+OUTPUT
TRIM
LOAD
RTRIM UP
–SENSE
–
5.11
– 10.22
Δ
VOUT – VNOM
Where Δ _ _
VNOM
+INPUT
–OUTPUT
Figure 3. Trim Connections To Increase Output Voltages
Connect sense to its respective VOUT pin if sense is not used with a remote load.
Note: “Δ” is always a positive value.
“VNOM” is the nominal, rated output voltage.
“VOUT” is the desired, changed output voltage.
–INPUT
+OUTPUT
+SENSE
ON/OFF
CONTROL
RTRIM DOWN
TRIM
LOAD
–SENSE
+INPUT
–OUTPUT
Figure 4. Trim Connections To Decrease Output Voltages
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19 Jul 2010
MDC_ULS Series.B16 Page 8 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
TYPICAL PERFORMANCE CURVES, ULS-3.3/20-D48
Efficiency vs. Line Voltage and Load Current @ 25°C
Maximum Current Temperature Derating at Sea Level
(VIN = 48V, longitudinal airflow)
25
100
Output Current (Amps)
95
Efficiency (%)
90
85
VIN = 75V
VIN = 48V
VIN = 36V
80
75
20
Natural convection
100 LFM
200 LFM
300 LFM
400 LFM
15
10
5
70
0
65
30
35
40
45
60
3
4
6
8
10
12
14
16
18
50
55
60
65
70
75
80
85
80
85
Ambient Temperature (ºC)
20
Load Current (Amps)
TYPICAL PERFORMANCE CURVES, ULS-5/12-D48
Efficiency and Power Dissipation @ 25°C
Maximum Current Temperature Derating at Sea Level
(VIN = 48V, airflow is from Vin to Vout)
90
10
85
9
VIN = 75V
VIN = 48V
VIN = 36V
80
75
8
7
70
6
65
5
60
Power Dissipation
(Vin = 48V)
55
50
3.0
4
3
2
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
12.0
13
Output Current (Amps)
11
Power Dissipation (Watts)
12
95
Efficiency (%)
100
12
Natural convection
11
10
9
8
7
30
35
40
45
50
55
60
65
70
75
Ambient Temperature (ºC)
Load Current (Amps)
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MDC_ULS Series.B16 Page 9 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
TRANSIENT RESPONSE, ULS-3.3/20-D48
(Resistive loads 50% with +25% step Vin=48V)
Transient Response (Load from 75% to 50%)
Transient Response (Load from 50% to 75%)
Enable Start-up
Enable Start-up (Vin=48V Iout=20A)
Ripple and Noise (1uF Ceramic and 10uF Tantalum Capcitors)
Enable Start-up (Vin=48V Iout=0A)
R/N Waveform (Vin=48V Iout=20A)
R/N Waveform (Vin=48V Iout=0A)
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MDC_ULS Series.B16 Page 10 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
TYPICAL PERFORMANCE CURVES, ULS-12/2.5-D48
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
0.25
Power Dissipation vs. Load Current @ 25°C
4.5
4.0
Power Dissipation (Watts)
Efficiency (%)
Efficiency vs. Line Voltage and Load Current @ 25°C
VIN = 75V
VIN = 60V
VIN = 48V
VIN = 36V
3.5
3.0
2.5
VIN = 75V
VIN = 60V
VIN = 48V
VIN = 36V
2.0
1.5
1.0
0.5
0.48
0.70
0.93
1.15
1.38
1.60
1.83
2.05
2.28
0.3
0.5
0.7
0.9
1.2
1.4
1.6
1.8
2.1
2.3
2.5
2.50
Load Current (Amps)
Load Current (Amps)
Maximum Current Temperature Derating at Sea Level
(VIN = 36, 48, and 75V, airflow is from pin 3 to pin 1)
Maximum Current Temperature Derating at Sea Level
(VIN = 60V, airflow is from pin 3 to pin 1)
3.0
Output Current (Amps)
Output Current (Amps)
3.0
2.5
65 LFM
2.0
2.5
100 LFM
65 LFM
2.0
30
35
40
45
50
55
60
65
70
75
80
85
30
35
40
45
50
55
60
65
70
75
80
85
Ambient Temperature (ºC)
Ambient Temperature (ºC)
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MDC_ULS Series.B16 Page 11 of 12
ULS Series
Sixteenth-brick DOSA-Compatible,
Isolated DC/DC Converters
TYPICAL PERFORMANCE CURVES, ULS-12/5-D48
12
95
11
90
10
9
85
80
8
VIN = 75V
VIN = 48V
VIN = 36V
75
70
7
6
5
65
60
Power Dissipation
(Vin = 48V)
55
50
0.50
0.95
1.40
1.85
2.30
2.75
3.20
3.65
4.10
4.55
4
6
Output Current (Amps)
100
Maximum Current Temperature Derating at Sea Level
(VIN = 48V, airflow is from Vin to Vout)
Loss (Watts)
Efficiency (%)
Efficiency and Power Dissipation vs. Line Voltage and Load Current @ 25°C
5
4
Natural convection
100 LFM
200 LFM
300 LFM
400 LFM
3
2
1
3
2
5.00
0
30
35
40
45
50
55
60
65
70
75
80
85
Ambient Temperature (ºC)
Load Current (Amps)
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
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. Specifications are subject to change without
notice.
© 2010 Murata Power Solutions, Inc.
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19 Jul 2010
MDC_ULS Series.B16 Page 12 of 12