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UHP-28.2/12-D48
Isolated, 12 Amp Half Brick, 48VIN/28.2VOUT DC/DC Converters
OBSOLETE PRODUCT
ORDERING GUIDE SUMMARY
Model
VOUT Range
IOUT Range
VIN Range
Ripple/Noise
Efficiency
28.2V
0-12A
36-75V
100mVp-p
91.5%
UHP-28.2/12-D48
Typical unit
FEATURES
INPUT CHARACTERISTICS
Parameter
Typ. @ 25°C, full load
Notes
Voltage Range
36-75 Volts
48V nominal
Current, full power
5.77 Amps
VIN = 48V
Undervoltage Shutdown
32 Volts
Short Circuit Current
200mA
VIN = 48V
Remote On/Off Control
0 to +VIN
Positive or negative logic
OUTPUT CHARACTERISTICS
Wide 36-75V input range
Parameter
■
28.2V output @ 12 Amps. max.
Voltage
28.2 Volts ±10%
Trim range shown
Very high efficiency of 91.5%
Current
0 to 12 Amps
No minimum load
■
342 Watts max.
Max. baseplate @ 342W = 80°C
■
Operates to +110°C baseplate w/derating
Power Output
Accuracy
±1.25%
■
Conduction-cooled baseplate, no fans
Ripple & Noise
100mVp-p
■
Industry-standard mounting and pinout
Line and Load Regulation
±0.05%/±0.1%
Overcurrent Protection
30 Amps
Overtemperature Protection
+125°C
■
Typ. @ 25°C, full load
■
Remote sense, trim and On/Off control
■
Isolated to 2250Vdc (Basic insulation)
Efficiency (minimum)
89.5%
■
Multiple I/O protection features
Efficiency (typical)
91.5%
■
UL/EN60950-1 safety approvals, CE mark
■
ETSI 300-019-2-4 surge, shock/vibration
DESCRIPTION
The UHP-28.2/12-D48 is especially designed for
unattended cellular and PCS base stations, remote
wide band RF amplifiers and wireless communication facilities. To avoid unreliable system fans,
the UHP-28.2/12-D48 can be operated using conduction cooling while attached to a housing wall
or system heat sink. No forced airflow is needed
up to +110°C baseplate temperature.
The UHP-28.2/12-D48's MTBF is 3 million hours
(+40°C GF) and ruggedization conforms to
ETSI 300-019-2-4. Multiple protection features
avoid damage to outside equipment and to the
converter itself. The converter will shut down on
sustained input undervoltage, output overcurrent,
output short circuit and overvoltage and thermal
shutdown. Overload currents less than a short
circuit limit the output current so that operation
Notes
20MHz bandwidth
With hiccup auto-restart
GENERAL SPECIFICATIONS
Parameter
Typ. @ 25°C, full load
Notes
Dynamic Load Response
100μsec
50-75-50% step to ±1 of final value
Operating Temperature Range
–40 to +110°C
With baseplate, see derating curve
Operating Temperature Range
–40 to +32°C
Without baseplate
Safety
UL/IEC/EN 60950-1
And CSA C22.2-No.234
MECHANICAL CHARACTERISTICS
With baseplate
2.30 x 2.40 x 0.502 inches (58.4 x 61.0 x 12.8 mm)
Without baseplate
2.30 x 2.40 x 0.452 inches (58.4 x 61.0 x 11.5 mm)
is not interrupted. Upon short circuit shutdown,
the converter will automatically attempt to restart
(“hiccup” mode) when the overload is removed.
The input will tolerate up to 100V overvoltage
spikes (100msec).
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The UHP-28.2/12-D48 uses industry-standard
half-brick external outline dimensions, pinout and
mechanical mounting. The overall unit is designed
to be as “lead-free” as practical in construction
and method of attachment (no lead added in
assembly).
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
UHP_28.2/12_D48.B02 Page 1 of 9
UHP-28.2/12-D48
Isolated, 12 Amp Half Brick, 48VIN/28.2VOUT DC/DC Converters
PERFORMANCE SPECIFICATIONS AND ORDERING GUIDE ➀
Output
Model
UHP-28.2/12-D48
➀
➁
➂
➃
Input
Load ➂
VIN Nom.
(Volts)
Range
(Volts)
IIN ➃
(mA/A)
Min.
Typ.
Package
(Case/
Pinout)
±0.1%
48
36-75
75/7.06
89.5%
91.5%
C66, P17
Regulation
R/N (mVp-p) ➁
VOUT
(Volts)
IOUT
(Amps)
Typ.
Max.
Line
28.2
12
100
160
±0.05%
Efficiency
Typical at TA = +25°C under nominal line voltage and full-load conditions, unless noted.
Ripple/Noise (R/N) is measured over a 20MHz bandwidth and input filter.
Regulation is tested no load to 100% load.
Nominal line voltage, no-load/full-load conditions.
PART NUMBER STRUCTURE
UHP - 28.2 / 12 - D48 N B
Unipolar High-Power
Nominal Output Voltage:
28.2 Volts
On/Off control Polarity
Baseplate:
Blank = not installed, standard
B = Installed, optional
P = Positive, optional
N = Negative, standard
Maximum Output Current:
12 Amps
Note: Some model number combinations
may not be available. Please contact
Murata Power Solutions.
Input Voltage Range:
D48 = 36-75 Volts (48V nominal)
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Typical topology is shown.
Figure 1. Simplified Schematic
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Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
UHP_28.2/12_D48.B02 Page 2 of 9
UHP-28.2/12-D48
Isolated, 12 Amp Half Brick, 48VIN/28.2VOUT DC/DC Converters
Performance/Functional Specifications
Dynamic Characteristics
Typical @ TA = +25°C under nominal line voltage, full-load conditions, unless noted.
(1)
Dynamic Load Response (50-75-50%step) 100µsec to ±1% of final value
Input
Load Step Peak Deviation
±600mV
360msec for VOUT = nominal
34 Volts
Start-Up Time
(VIN on to VOUT regulated or On/Off to VOUT)
32 Volts
Switching Frequency
320kHz
Input Voltage Range
See Ordering Guide
Start-Up Threshold
Undervoltage Shutdown
Voltage Transients (100msec, no damage) +100 Volts max.
Environmental
Overvoltage Shutdown
None (7)
Calculated MTBF (4)
>3,000,000 Hours
Reflected (Back) Ripple Current (2)
50mAp-p
–40 to +110°C max.
Input Current:
Full Load Conditions
Inrush Transient
Output Short Circuit
No Load
Low Line (VIN = VMIN)
Standby Mode
(Off, UV, OT, OC shutdown)
Baseplate Temperature Range
(See derating curve) (3) (13)
See Ordering Guide
1A2sec
200mA
75mA
9.37 Amps
10mA max.
Storage Temperature Range
–55 to +125°C
Thermal Protection/Shutdown (13)
+115°C
Internal Input Filter
Pi-type
Outline Dimensions
See Mechanical Specifications
Recommended External Fuse
18 Amps slow blow
Baseplate Material
Aluminum
Reverse Polarity Protection
See fuse information
Pin Material
Copper alloy
Weight
3.9 ounces (110 grams)
Electromagnetic Interference
Conducted and radiated
FCC part 15, class B, EN55022 (external filter required)
Safety
IEC/EN 60950 UL1012
UL/cUL 60950-1 CSA-C22.2 No.234
Surge, Shock, Vibration
ETSI 300-019-2-4
Flammability
ULV94-0
Remote On/Off Control: (5)
Positive Logic ("P" model suffix)
Negative Logic ("N" model suffix)
Current
To 85% / +85°C, non-condensing
Acoustic Output 20Hz to 20kHz
No audible output in normal
office environments (15)
Physical
ON = open pin or +2.8V to +12V max.
OFF = ground pin to +0.8V max.
ON = ground pin to +0.8V max.
OFF = open pin or +2.8V to +12V max.
1mA
Output
Total Output Power
Relative Humidity
342 Watts max.
Voltage Output Range
See Ordering Guide
Voltage Output Accuracy
±1 % of Vnominal
Absolute Maximum Ratings
Overvoltage Protection (14)
Method
+125% of VOUT nominal
Magnetic feedback
Input Voltage
Continuous
Transient (100 msec max.)
to +75V
to +100V
On/Off Control
–0.3 V min to +12V max.
Input Reverse Polarity Protection
See Fuse section (11)
Output Overvoltage
VOUT +25% max.
Output Current (7)
Current-limited. Devices can
withstand sustained short circuit
without damage.
–55 to +125°C
Voltage Adjustment Range
(12)
+25.4V min. to +31V max.
Temperature Coefficient
±0.02% of VOUT range per °C
Minimum Loading
No minimum load
Remote Sense Compensation
+1% max.
Ripple/Noise (20 MHz bandwidth)
See Ordering Guide
Line/Load Regulation
See Ordering Guide and note
Efficiency
See Ordering Guide
Storage Temperature
Maximum Capacitive Loading (Resistive)
3300µF (Low ESR <0.02W max.)
Lead Temperature (soldering 10 sec. max.)
Isolation Voltage:
Input to Output
Input to Baseplate
Baseplate to Output
(8)
(10)
2250Vdc min.
1500Vdc min.
750Vdc min.
Isolation Resistance
100MW
Isolation Capacitance
2000 pF
Isolation Safety Rating
Basic insulation
Current Limit Inception (98% of VOUT)
16 Amps at cold start
15 Amps after warmup
Short Circuit (6)
Protection Method
Short Circuit Current
Short Circuit Duration
Current limiting with hiccup autorestart
TBD
Continuous, output shorted to ground
(no damage)
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+280°C
These are stress ratings. Exposure of devices to 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, nor recommended.
Performance/Functional Specification Notes:
The UHP-28.2/12-D48 is tested and specified with external 1 || 10 µF ceramic/tantalum
output capacitors and a 22µF 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 specified performance in your applications. All models are stable and regulate within
spec under no-load conditions.
General conditions for Specifications are +25°C, VIN = nominal, VOUT = nominal, full load.
(2) Input Ripple Current is tested and specified over a 5Hz to 20MHz bandwidth. Input filtering is
CIN = 33µF tantalum, CBUS = 220µF electrolytic, LBUS = 12µH.
(1)
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
UHP_28.2/12_D48.B02 Page 3 of 9
UHP-28.2/12-D48
Isolated, 12 Amp Half Brick, 48VIN/28.2VOUT DC/DC Converters
Performance/Functional Specification Notes:
Note that Maximum Power Derating curves indicate an average current at nominal input voltage.
At higher temperatures and/or lower airflow, the DC/DC converter will tolerate brief full current
outputs if the total RMS current over time does not exceed the Derating curve.
(4) Mean Time Before Failure is calculated using the Telcordia (Belcore) SR-332 Method 1,
Case 3, ground fixed conditions, TCASE = +40°C, full output load, natural air convection.
(5) The On/Off Control may 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/open drain transistor or logic gate which does not exceed +12V.
(6) Short circuit shutdown begins when the output voltage degrades approximately 2% from the
selected setting. Remove overload for recovery.
(7) Input overvoltage shutdown is explicitly not included to improve system reliability in datacom and
telecom applications. These requirements attempt continued operation despite significant input
overvoltage.
(8) Output noise may be further reduced by adding an external filter. See I/O Filtering and Noise
Reduction. Use only as much external output filtering as needed and no more. Larger caps
(especially low-ESR ceramic types) may degrade dynamic performance or cause possible failed
starts. Thoroughly test your application with all components installed.
(9) Models are fully operational and meet published specifications, including “cold start” at –40°C.
(10) Regulation specifications describe the deviation as the line input voltage or output load current is
varied from a nominal midpoint value to either extreme.
(11) If the input voltage is reversed, a normally back-biased bulk substrate diode will become forward
biased and draw current. An external fuse is recommended to avoid damage from reverse input
current.
(12) Do not exceed maximum power specifications when adjusting the output trim.
(13) Note that the converter may operate derated up to +110°C with the baseplate installed. However,
thermal self-protection occurs near +115°C and there is a thermal gradient from the hotspot to
the baseplate. Therefore, +110°C is recommended to avoid thermal shutdown.
(14) If the output exceeds the Overvoltage specification, the output will shut down in latching mode.
To restore normal operation, either power down the unit or cycle the On/Off control.
(15) Acoustic output is measured by subjecting the converter to both 0-100-0% and 50-100-50%
step loads at load pulse frequencies of 100Hz, 300Hz and 1kHz.
TECHNICAL NOTES
(3)
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 UHP Series DC/DC Converters, we recommend the
use of slow-blow type fuses, installed in the ungrounded input supply line,
with values no greater than the following.
Output
Fuse Value
28 VOUT 18 Amp
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.
Input Undervoltage 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 Undervoltage 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 interval of time between the point at which
the ramping input voltage crosses the Start-Up Threshold and the fully loaded
output voltage enters and remains within 90% of VOUT . 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 UHP Series implements a soft start circuit that limits 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 Overvoltage Shutdown
The UHP Series does not feature input overvoltage shutdown. The converters
do withstand and fully operate during input transients to 100V for 100msec
without interruption; consequently, this function has been disabled.
Input Source Impedance
The input of UHP 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 2 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 as
close as possible to the DC/DC converter.
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UHP_28.2/12_D48.B02 Page 4 of 9
UHP-28.2/12-D48
Isolated, 12 Amp Half Brick, 48VIN/28.2VOUT DC/DC Converters
I/O Filtering, Input Ripple Current, and Output Noise
All models in the UHP 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 2) 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-ripplecurrent 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 2, CBUS and L♥ simulate a typical dc
voltage bus. Your specific system configuration may necessitate additional
considerations.
TO
OSCILLOSCOPE
CURRENT
PROBE
VIN
CBUS
+OUTPUT
6
COPPER STRIP
5
C1
–OUTPUT
–SENSE
C2
SCOPE
RLOAD
9
8
COPPER STRIP
C1 = 0.1µF CERAMIC
C2 = 10µF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE
Figure 3. Measuring Output Ripple/Noise (PARD)
4
+INPUT
LBUS
+
+SENSE
CIN
–
1
–INPUT
CIN = 33µF, ESR < 700mΩ @ 100kHz
CBUS = 220µF, ESR < 100mΩ @ 100kHz
LBUS = 12µH
Minimum Output Loading Requirements
UHP 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.
Thermal Shutdown
Figure 2. 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. Our Applications Engineers can recommend potential solutions and
discuss the possibility of our modifying a given device's internal filtering to
meet your specific requirements. Contact our Applications Engineering Group
for additional details.
In Figure 3, 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 as short as possible (i.e. 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 (pin 9) as the
ground/return of the load circuit. You can however, use the +Output (pin 5) as
ground/return to effectively reverse the output polarity.
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The UHP 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 Overvoltage Protection
The UHP output voltage is monitored for an overvoltage 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 overvoltage circuitry will
initiate another shutdown cycle. This on/off cycling is referred to as "hiccup"
mode.
Current Limiting
As soon as the output current increases to approximately 125% 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.
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UHP_28.2/12_D48.B02 Page 5 of 9
UHP-28.2/12-D48
Isolated, 12 Amp Half Brick, 48VIN/28.2VOUT DC/DC Converters
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 UHP Series is capable of
enduring an indefinite short circuit output condition.
Features and Options
Remote Sense
Note: The Sense and VOUT lines are internally connected through resistors
(=<10Ω). 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.
UHP 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. In cables and discrete wiring
applications, twisted pair or other techniques should be implemented.
overvoltage protection circuitry to activate (see Performance Specifications for
overvoltage 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 conveter's specified rating, or cause output voltages to climb into the
output overvoltage region. Therefore, the designer must ensure:
(VOUT at pins) x (IOUT ) =< rated output power
On/Off Control
The primary-side, Remote On/Off Control function (pin 3) can be specified to
operate with either positive or negative polarity. Positive-polarity devices ("P"
suffix) are enabled when pin 3 is left open or is pulled high. Positive-polarity
devices are disabled when pin 3 is pulled low (0-0.8V with respect to –Input).
Negative-polarity devices are off when pin 3 is high/open and on when pin 3
is pulled low or grounded. See Figure 5.
4
+INPUT
EQUIVALENT CIRCUIT FOR
POSITIVE AND NEGATIVE
LOGIC MODELS
+
3
CONTROL
ON/OFF
CONTROL
1
REF
–INPUT
Figure 5. Driving the On/Off Control Pin
1
–INPUT
+OUTPUT
+SENSE
3
6
IOUT
Sense Current
ON/OFF
CONTROL
TRIM
–SENSE
4
Contact and PCB resistance
losses due to IR drops
5
7
8
LOAD
Sense Return
IOUT Return
+INPUT
–OUTPUT
9
Contact and PCB resistance
losses due to IR drops
Figure 4. Remote Sense Circuit Configuration
UHP Series converters will compensate for drops between the output voltage
at the DC/DC and the sense voltage at the DC/DC provided that:
[VOUT (+) –VOUT (–)] –[Sense(+) –Sense (–)] =< 10% VOUT
Output overvoltage 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
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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.
Trimming Output Voltage
UHP converters have a trim capability (pin 7) that allows users to adjust the
output voltage within the specified range. Adjustments to the output voltages
can be accomplished via a trim pot (Figure 6) or a single fixed resistor, shown
in Figures 7 and 8. A single fixed resistor can increase or decrease the output
voltage depending on its connection. The resistor should be located close to
the converter and have a TCR less than 100ppm/°C to minimize sensitivity to
temperature changes. If the trim function is not used, leave the trim pin floating.
A single resistor connected from the Trim (pin 7) to the +Sense (pin 6), will
increase the output voltage (Figure 8). A resistor connected from the Trim (pin
9) to the –Sense (pin 8), will decrease the output voltage (Figure 9).
Trim adjustments greater than the specified range can have an adverse affect
on the converter's performance and are not recommended. Excessive voltage
differences between VOUT and Sense, in conjunction with trim adjustment of
the output voltage, can cause the overvoltage protection circuitry to activate
(see Performance Specifications for overvoltage limits). Power derating is
based on maximum output current and voltage at the converter's output
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
UHP_28.2/12_D48.B02 Page 6 of 9
UHP-28.2/12-D48
Isolated, 12 Amp Half Brick, 48VIN/28.2VOUT DC/DC Converters
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 overvoltage region. Therefore:
TYPICAL PERFORMANCE CURVES
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(VOUT at pins) x (IOUT ) =< rated output power
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Figure 6. Trim Connections Using A Trim Pot
1
+OUTPUT
–INPUT
+SENSE
TRIM
3
4
–SENSE
–OUTPUT
5
–INPUT
+OUTPUT
+SENSE
TRIM
3
7
LOAD
4
+INPUT
–SENSE
–OUTPUT
9
5
6
7
LOAD
8
9
Figure 8. Trim Connections To Decrease Output Voltages Using Fixed Resistors
Trim Equations
RTUP (kW) = 10 (
1036
) + 936
D%
RTDOWN (kW) = 10 (
100
)–2
D%
where D% is the desired change of the output voltage in percent relative to VNOMINAL. Or,
±D% =
UHP Converter Series Mounting
The UHP series include a multilayer planar-magnetic Printed Circuit Board
(PCB), high-current Input/Output pins, four removable brass mounting standoffs
and an optional machined aluminum baseplate. See Mechanical Specifications.
8
RTRIM DOWN
ON/OFF
CONTROL
6
Figure 7. Trim Connections To Increase Output Voltages Using Fixed Resistors
1
,OAD#URRENT!MPS
RTRIM UP
ON/OFF
CONTROL
+INPUT
VOUT – VNOM
x 100
VNOM
A user’s installation will normally have a host PCB to solder to the converter’s
I/O pins. To avoid placing the full mechanical mounting load on the I/O pins,
we recommend that the user’s PCB also includes bolts through the PCB to
assemble to the standoffs. Note the #M3 metric threading of the standoffs.
Avoid excessive torque assembling the bolts to the standoffs. Use lock washers or locking compound to avoid loosening of the mounting bolts.
The standoffs include machined shoulders so that mechanical force is not
placed against the converter’s power components. To avoid long-term oxidation of the host PCB, be sure to accommodate the relatively high temperatures
of the power components adjacent to the user’s host PCB. Normally, a planar
grounded area of copper etch on the PCB surface will be sufficient to spread
the heat, reduce electrical noise and avoid hotspots. A relief dimension on the
standoffs floats the power components 0.02 inches minimum from the user’s
host PCB.
The baseplate is in thermal contact with the power components and practically all the converter’s internal heat dissipation is conducted away via the
baseplate. Users typically have two choices to remove this thermal load—
either an extruded aluminum finned heat sink or a thermal mounting surface
such as a chassis wall. The heatsink depends on ambient temperature, airflow
and total power extracted from the converter, depending on the input voltage
and converter efficiency. Do not attempt to conduct all baseplate heat solely
through the standoffs. Use either a thermal pad or thermal mounting compound (“thermal grease”) when attaching the baseplate to its mounting surface. Keep baseplate temperature below +110°C. Study the Derating Curve.
For chassis wall mounting, the user must consider the tolerance buildup—the
host PCB, mounting standoffs, thermal pad and placement of the chassis wall.
Measure carefully to avoid unwanted mechanical stresses.
www.murata-ps.com
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
UHP_28.2/12_D48.B02 Page 7 of 9
UHP-28.2/12-D48
Isolated, 12 Amp Half Brick, 48VIN/28.2VOUT DC/DC Converters
MECHANICAL SPECIFICATIONS
Case C66
2.30
(58.4)
A
B
B
1.900
(48.3)
A
I/O CONNECTIONS
BASEPLATE
2.40
(61.0)
2.000
(50.8)
#M3 x 0.50
THREAD THROUGH
Pin
Function P17
1
–Input
2
Case
3
On/Off Control
4
+Input
5
+Output
6
+Sense
7
Trim
8
–Sense
9
–Output
Connect each sense input to its respective Vout
if sense is not connected at a remote load.
0.53 MAX.
(13.5)
0.49 (12.5)
Without Baseplate
B
PINS 5 & 9:
0.080 ±0.001 (2.03 ±0.025)
B
0.15 MIN.
(3.8)
0.24Ø (6.1) Brass Standoff
TYP. 4 PL
PINS 1-4, 6-8:
0.040Ø ±0.001
(1.016 ±0.025)
9
1
Dimensions are in inches (mm shown for ref. only).
Third Angle Projection
8
2
1.40
(35.56)
7
6
3
Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 2˚
5
4
0.30
(7.62)
1.900
(48.3)
0.60
(15.24)
Components are shown for reference only.
A
BOTTOM VIEW
DIMENSIONS ARE IN INCHES (MM)
www.murata-ps.com
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
UHP_28.2/12_D48.B02 Page 8 of 9
UHP-28.2/12-D48
Isolated, 12 Amp Half Brick, 48VIN/28.2VOUT DC/DC Converters
Thermal Management
“Zero Airflow” Passive Cooling Enclosure Installations
The UHP-28.2/12-D48 converter will deliver its full rated power as long as
the user maintains the baseplate at +80°C or less. Usable power is available
derated up to +110°C baseplate temperature. Please see the “baseplate”
Derating curve below. This curve is different from standard Derating curves
because no airflow is indicated. This is a reflection of the requirement to
only limit the baseplate temperature since the majority of the heat flows out
through the baseplate. Some heat is removed via airflow convection over the
converter.
UHP-28.2/12-D48N Maximum Baseplate Temperature vs. Output Power (6).6
Output Power (Watts)
“No airflow” applications are normally those with the converter bolted to a
chassis wall or other large heat-conducting surface. For such wall installations, there is no explicit airflow specification and the converter may be used
with zero airflow as long as the baseplate does not exceed +110°C.
Consider using thermal pads or compound (“thermal grease”) to lower the
thermal resistance between the baseplate and the chassis wall. Do not rely
only on the baseplate mounting screws to transfer heat. Also, since a housing
wall is not an infinite heat sink, most real-world enclosure installations are
improved by moderate forced airflow. This airflow cools both the mounting
surface and the converter itself by convection. Larger area and/or a thicker
mounting surface material will conduct more heat away and allow higher
output power.
Because of the high efficiency of the converter, the mounting surface only
carries away the internal dissipation of the converter, not the entire power
output. For computation purposes, the enclosure surface may use the following dissipation equations:
P(diss) = PowerIn – PowerOut and,
PowerOut / PowerIn x 100 = Efficiency (in %) and,
P(diss) = PowerIn (1 – Efficiency/100)
where “P(diss)” is the internal power dissipation of the converter.
Efficiency is given in percent. For example, with 92% efficiency at VIN = 48V
and 300 Watts out, P(diss) is 24 Watts.
Heat Sink Usage
Baseplate Temperature (°C)
Figure 9. Maximum Baseplate Temperature vs. Output Power
The UHP-28.2/12-D48 converter is primarily intended for baseplate and
enclosure mount installations. However, if you prefer to attach the converter’s
baseplate to an extruded aluminum heatsink in a traditional fan-forced airflow
installation, the user must carefully compute the thermal resistance of the
heat sink versus the power dissipation versus the ambient temperature and
airflow over the heatsink. As with the passive mounting surface installations,
the baseplate temperature should never exceed +110°C.
USA:
Mansfield (MA), Tel: (508) 339-3000, email: sales@murata-ps.com
Canada: Toronto, Tel: (866) 740-1232, email: toronto@murata-ps.com
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356
UK:
Milton Keynes, Tel: +44 (0)1908 615232, email: mk@murata-ps.com
France:
Montigny Le Bretonneux, Tel: +33 (0)1 34 60 01 01, email: france@murata-ps.com
Germany: München, Tel: +49 (0)89-544334-0, email: munich@murata-ps.com
www.murata-ps.com email: sales@murata-ps.com ISO 9001 REGISTERED
Japan:
Tokyo, Tel: 3-3779-1031, email: sales_tokyo@murata-ps.com
Osaka, Tel: 6-6354-2025, email: sales_osaka@murata-ps.com
Website: www.murata-ps.jp
China:
Shanghai, Tel: +86 215 027 3678, email: shanghai@murata-ps.com
Guangzhou, Tel: +86 208 221 8066, email: guangzhou@murata-ps.com
07/10/08
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. © 2008 Murata Power Solutions, Inc.
www.murata-ps.com
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
UHP_28.2/12_D48.B02 Page 9 of 9