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HEN D12 Models
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
Typical Unit
Eighth brick, through hole or SMT
with fast transient response
2-phase buck regulators for new
distributed 12V power architectures
12V input (10.2-13.8V range)
The HEN D12 Series of non-isolated eighth bricks with high di/dt are ideal
building blocks for emerging, on-board power-distribution schemes in which isolated
12V buses deliver power to any number of non-isolated, step-down buck regulators.
HEN D12 DC/DC's accept a 12V input (10.2V to 13.8V input range) and convert it,
with the highest efficiency in the smallest space, to a 0.8, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3 or 5 Volt
output fully rated at 25 Amps.
HEN D12's are ideal POLPP's (point-of-use/load power processors) and they typically require
no external components. They occupy the standard eighth-brick board space (0.9" x 2.3") and
come in either through-hole packages or surface-mount packages with a profile of only 0.39
inches (0.5" including optional heat sink).
The HEN's best-in-class power density is achieved with a fully synchronous,
fixed-frequency, 2-phase buck topology that delivers extremely high efficiency (92.5%
for 5VOUT models), low noise (10mVp-p typ.), extremely tight line/load regulation
(±0.05%/0.1%max.), fast transient response (50A/μsec with full-load step), stable
no-load operation, and no output reverse conduction.
The fully functional HEN's feature input over/undervoltage lockout, output overvoltage and
overcurrent detection, continuous short-circuit protection, overtemperature protection, an
output-voltage trim function, a remote on/off control pin, and a sense pin. High efficiency
enables the HEN D12's to deliver rated output currents of
25 Amps at ambient temperatures to +65°C with 200 lfm air flow without heat sink.
If your new system boards call for multiple supply voltages, check out the
economics of on-board 12V distributed power. If you don't need to pay for multiple
isolation barriers, DATEL's non-isolated 1/4- and 1/8-bricks will save you money. Selected
models are RoHS-6 (Restriction of Hazardous Substances) compliant.
0.8/1/1.2/1.5/1.8/2/2.5/3.3/5VOUT @ 25A
Non-isolated, fixed-frequency,
synchronous-rectifier topology
Efficiencies to 87% @ 25 Amps
Noise as low as 10mVp-p
Stable no-load operation
On/Off control, trim & sense functions
Output Overvoltage Protection
Input Over/Undervoltage lockout
Thermal shutdown
Designed to meet UL/EN/IEC 60950-1 and CAN/
CSA C22.2 60950-1
EMC compliant
(6, 8)
Only one phase of two shown.
Figure 1. Simplified Schematic
Typical topology is shown
For full details go to
MDC_HEN-D12.C02 Page 1 of 11
HEN D12 Models
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
Performance Specifications and Ordering Guide ➀
Root Model ➄
R/N (mVp-p) ➁
Regulation (Max.) ➂
VIN Nom.
Range ➅
(Case, Pinout)
C47,C48, P62
C47,C48, P62
Full Load
C47,C48, P62
Please contact Murata Power Solutions for further information.
C47,C48, P62
C47,C48, P62
C47,C48, P62
C47,C48, P62
C47,C48, P62
C47,C48, P62
Please contact Murata Power Solutions for further information.
➀ Typical at TA = +25°C under nominal line voltage and full-load conditions, unless otherwise
noted. All models are tested and specified with an external 33μF input and output capacitors.
These capacitors are necessary to accomodate our test equipment and may not be required to
achieve performance in your application. All models are stable and regulate within spec under
no-load conditions.
➁ Ripple/Noise (R/N) is tested/specified over a 20MHz bandwidth and may be reduced with
external filtering. See I/O Filtering and Noise Reduction for details.
➂ These devices have no minimum-load requirements and will regulate under no-load conditions.
Regulation specifications describe the output-voltage deviation as the line voltage or load is
varied from its nominal/midpoint value to either extreme.
➃ Nominal line voltage, no-load/full-load conditions.
➄ Please refer to the Part Number Structure for additional options when ordering.
➅ The operating input voltage is 10.2V to 13.8V. However, 10.8VIN is required for the DC/DC to
properly start up under all line, load and temperature conditions. The 10.8V potential must be
maintained across the inputs until the output is up and regulating. After the output is regulating, the operating input range is 10.2V to 13.8V.
H EN - 1.8 / 25 - D12 M H - C
H = Unipolar
High di/dt
RoHS hazardous
substance compliant
Heat Sink Option
Surface-Mount Package
Non-Isolated Eighth Brick
Input Voltage Range:
D12 = 10.2 to 13.8 Volts
(12V nominal)
Nominal Output Voltage:
0.8, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3
or 5 Volts
Not all model number combinations are available.
Contact Murata Power Solutions.
Case C47
I/O Connections
Function P62
Function P62
On/Off Control
Maximum Rated Output
Current in Amps
Special customer configuration part number: HEN-1.2/25-D12M-C-CIS
C47,C48, P62
%130 "/44/-6)%7
Case C48
See Heatsink Installation and Automated Assembly and Production Notes for details
Component locations are typical and may vary with different models.
MDC_HEN-D12.C02 Page 2 of 11
HEN D12 Models
Performance/Functional Specifications
Typical @ TA = +25°C under nominal line voltage and full-load conditions unless noted. ➀
Input Voltage Range
10.2-13.8 Volts (12V nominal) ➉
Input Current:
Normal Operating Conditions
Inrush Transient ➆
Standby/Off Mode
Output Short-Circuit Condition
See Ordering Guide
0.04A2sec maximum
Input Reflected Ripple Current ➁
Input Filter Type
Overvoltage Protection
14.3 Volts
Reverse-Polarity Protection
Undervoltage Shutdown
9.5 Volts
No-Load Input Current
Remote On/Off Control: ➄
On = open (internal pull down), 0 to +0.8V
Off = +2.5V to +VIN or pulled high
Remote Control On/Off Current
0.75mA maximum
Remote Sense Input Range
±10% of VOUT
VOUT Accuracy (50% load)
Minimum Loading ➀
No minimum load
Maximum Output Power ➇
30.45W (1.2V), 38.06W (1.5V models)
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
➀ All models are tested and specified with an external 33μF tantalum input capacitor and
3000μF POSCAP and 300μF ceramic external output capacitors except where noted.
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.
➁ Input Ripple Current is specified with no external filter.
➂ Current Limit Inception is given at either cold startup or after warmup.
➃ MTBF is calculated using Telcordia (Bellcore) SR-332, Method 1, Case 3, ground-fixed
conditions, TCASE = +25°C, full load, natural convection, +67°C maximum pcb temperature.
➄ The On/Off Control (pin 4) may be driven with open-collector logic or the application of
appropriate voltages (referenced to Common, pin 1).
➅ The short circuit current is an average which includes brief, full-current hiccup pulses.
➆ Startup inrush current should be used to compute proper external fusing, if installed. The
fuse rating will depend on the fuse thermal time constant ("slow blow"), and other factors.
➇ VOUT times IOUT must not exceed maximum power.
➈ See Technical Notes.
➉ See note 6, page 2.
Absolute Maximum Ratings
Input Voltage:
Transient (100msec maximum)
14 Volts
15 Volts
On/Off Control (Pin 4)
Input Reverse-Polarity Protection
Output Overvoltage Protection
VOUT +20%
Output Current
Current limited. Devices can
withstand sustained output short
circuit without damage.
Maximum Capacitive Loading
40,000µF (electrolytic, ESR <10m)
VOUT Trim Range ➇
Storage Temperature
–55 to +125°C
Ripple/Noise (20MHz BW)
See Ordering Guide
Lead Temperature (soldering, 10 sec.)
+280°C (Refer to Solder Profile)
Total Accuracy
±3% over line, load and temperature
Temperature Coefficient at All Outputs ±0.02%/°C
See Ordering Guide
Overcurrent Detection and Short-Circuit Protection:
Current-Limiting Detection
42 Amps, cold startup (35A after warmup)
Hiccup with auto recovery
Short-Circuit Protection Method ➈
2.5A, 4A maximum average
Short-Circuit Current ➅
Short-Circuit Duration
Continuous, output shorted to ground
Dynamic Characteristics
Transient Response:
(50-100% load step to±1.5%VOUT)
30µsec typical, 60µsec maximum
Start-Up Time:
VIN to VOUT or On/Off to VOUT
10msec maximum for VOUT = nominal
Switching Frequency
660kHz ±10%
Calculated MTBF ➃
TBD million hours
Operating Temperature:
–40 to +85°C with derating
Storage Temperature Range
–55 to +125°C
Thermal Protection Shutdown
Relative Humidity
To 85% / +85°C non-condensing
See Mechanical Specifications
Pin Material
Gold-plated copper alloy with nickel
0.6 ounces (17g)
Flamability Rating
Electromagnetic Interference
(may need external filter)
Conducted and radiated to FCC part
EN55022 Class A
Designed to meet UL/cUL/IEC/EN 60950-1,
CSA-C22.2 No. 60950-1
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 or recommended.
Return Current Paths
The HEN D12 are non-isolated DC/DC converters. Their Common pins (pins
1, 6 and 8) are connected to each other internally (see Figure 1). To the
extent possible (with the intent of minimizing ground loops), input return
current should be directed through pin 1 (also referred to as –Input or Input
Return), and output return current should be directed through pin 6 and 8
(also referred to as –Output or Output Return). Any on/off control signals
applied to pin 4 (On/Off Control) should be referenced to Common
(specifically pin 1).
I/O Filtering and Noise Reduction
All models in the HEN D12 Series are tested and specified with external
33μF tantalum input and output capacitors. These capacitors are necessary
to accommodate our test equipment and may not be required to achieve
desired performance in your application. The HEN D12's are designed with
high-quality, high-performance internal I/O caps, and will operate within
spec in most applications with no additional external components.
In particular, the HEN D12's input capacitors are specified for low ESR and
are fully rated to handle the units' input ripple currents. Similarly, the internal output capacitors are specified for low ESR and full-range frequency
response. As shown in the Performance Curves, removal of the external
33μF tantalum output caps has minimal effect on output noise.
In critical applications, input/output ripple/noise may be further reduced
using filtering techniques, the simplest being the installation of external I/O
MDC_HEN-D12.C02 Page 3 of 11
HEN D12 Models
External input capacitors serve primarily as energy-storage devices. They
minimize high-frequency variations in input voltage (usually caused by IR
drops in conductors leading to the DC/DC) as the switching converter draws
pulses of current. Input capacitors should be selected for bulk capacitance
(at appropriate frequencies), low ESR, and high rms-ripple-current ratings.
The switching nature of modern DC/DC's requires that the dc input voltage
source have low ac impedance and the frequencies of interest. Highly
inductive source impedances can greatly affect system stability. Your specific system configuration may necessitate additional considerations.
Output ripple/noise (also referred to as periodic and random deviations
or PARD) may be reduced below specified limits with the installation of
additional external output capacitors. Output capacitors function as true
filter elements and should be selected for bulk capacitance, low ESR, and
appropriate frequency response. Any scope measurements of PARD should
be made directly at the DC/DC output pins with scope probe ground less
than 0.5" in length.
All external capacitors should have appropriate voltage ratings and be
located as close to the converters as possible. Temperature variations for all
relevant parameters should be taken into consideration.
The most effective combination of external I/O capacitors will be a function
of your line voltage and source impedance, as well as your 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.
Input Fusing
Most applications and or safety agencies require the installation of fuses
at the inputs of power conversion components. HEN D12 Series DC/DC
converters are not internally fused. Therefore, input fusing is mandatory for
safety reasons, and safety agencies require a time delay fuse with a value
no greater than 40Amps, which should be installed within the ungrounded
input path to the converter.
As a rule of thumb however, we recommend to use a normal-blow or slowblow fuse with a typical value of about twice the maximum input current,
calculated at low line with the converters minimum efficiency.
Safety Considerations
HEN D12's are non-isolated DC/DC converters. In general, all DC/DC's
must be installed, including considerations for I/O voltages and spacing/
separation requirements, in compliance with relevant safety-agency specifications (usually UL/IEC/EN60950).
In particular, for a non-isolated converter's output voltage to meet SELV
(safety extra low voltage) requirements, its input must be SELV compliant.
If the output needs to be ELV (extra low voltage), the input must be ELV.
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
The On/Off to VOUT Start-Up Time assumes the converter is turned off via
the On/Off Control with the nominal input voltage already applied to the
converter. The specification defines the interval between the time at which
the converter is turned on and the fully loaded output voltage enters and
remains within its specified accuracy band. See Typical Performance
Remote Sense
HEN D12 Series DC/DC converters offer an output sense function on pin 10.
The sense function enables point-of-use regulation for overcoming moderate IR drops in conductors and/or cabling. Since these are non-isolated
devices whose inputs and outputs usually share the same ground plane,
sense is provided only for the +Output.
The remote sense line is part of the feedback control loop regulating the
DC/DC converter’s output. The sense line carries very little current and
consequently requires a minimal cross-sectional-area conductor. As such,
it is not a low-impedance point and must be treated with care in layout and
cabling. Sense lines should be run adjacent to signals (preferably ground),
and in cable and/or discrete-wiring applications, twisted-pair or similar
techniques should be used. To prevent high frequency voltage differences
between VOUT and Sense, we recommend installation of a 1000pF capacitor
close to the converter.
The sense function is capable of compensating for voltage drops between
the +Output and +Sense pins that do not exceed 10% of VOUT.
[VOUT(+) – Common] – [Sense(+) – Common]  10%VOUT
Power derating (output current limiting) is based upon maximum output
current and voltage at the converter's output pins. Use of trim and sense
functions can cause the output voltage to increase, thereby increasing
output power beyond the converter's specified rating. Therefore:
(VOUT at pins) x (IOUT)  rated output power
The internal 10 resistor between +Sense and +Output (see Figure 1)
serves to protect the sense function by limiting the output current flowing
through the sense line if the main output is disconnected. It also prevents
output voltage runaway if the sense connection is disconnected.
Note: If devices have the +Sense pin (pin 10) installed (no part-number
suffix) and the sense function is not used for remote regulation, +Sense
(pin 10) must be tied to +Output (pin 7, 9) at the DC/DC converter pins.
On/Off Control
The On/Off Control pin may be used for remote on/off operation. HEN D12
Start-Up Time
The VIN to VOUT Start-Up Time is the interval between the time at which a
ramping input voltage crosses the lower limit of the specified input voltage
range (10.2 Volts) 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 to the converter.
ON/OFF pin open:
ON/OFF pin >2.8V:
Logic Low = DC/DC converter On
Logic High = DC/DC converter Off
Figure 2. Driving the On/Off Control Pin
MDC_HEN-D12.C02 Page 4 of 11
HEN D12 Models
Series DC/DC converters are designed so that they are enabled when the
control pin is left open (or pulled low to 0 to +0.4V) and disabled when the
control pin is pulled high (+2.8V to +VIN). As shown in Figure 2, all models
have an internal 20k pull-down resistor to Common (ground).
Dynamic control of the on/off function is best accomplished with a mechanical relay or open-collector/open-drain drive circuit (optically isolated if
appropriate). The drive circuit should be able to sink appropriate current
when activated and withstand appropriate voltage when deactivated.
The on/off control can be driven using a circuit comparable to that shown in
Figure 2. Leaving the On/Off control pin open or applying a voltage between
0V and +0.4V will turn on the converter. Applied voltages between +2.8V
and +VIN will disable the converter.
Power-up sequencing
If a controlled start-up of one or more HEN D12 Series DC/DC converters
is required, or if several output voltages need to be powered-up in a given
sequence, the On/Off control pin can be pulled high to +VIN with an external
5.6k resistor. While input voltage and/or other converters are ramping up,
the control pin is pulled high and the converter remains disabled. To enable
the output voltage, the control pin needs to be pulled low in the configuration shown in Figure 3.
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
D12's internal overcurrent-detection circuitry immediately turns off the
converter, which then goes into a "hiccup" mode. While hiccupping, the
converter will continuously attempt to restart itself, go into overcurrent, and
then shut down. Under these conditions, both the average output current
and the average input current will be kept extremely low. Once the output
short is removed, the converter will automatically restart itself.
Output Voltage Trimming
Allowable trim ranges are ±10%. Trimming is accomplished with either a
trimpot or a single fixed resistor. The trimpot should be connected between
+Output and Common with its wiper connected to the Trim pin as shown in
Figure 4 below.
A trimpot can be used to determine the value of a single fixed resistor
which can then be connected, as shown in Figure 5, between the Trim pin
and +Output to trim down the output voltage, or between the Trim pin and
Common to trim up the output voltage. Fixed resistors should have absolute
TCR’s less than 100ppm/°C to ensure stability.
The equations below can be starting points for selecting specific trim-resistor
values. Recall, untrimmed devices are guaranteed to be ±1.5% accurate.
Adjustment beyond the specified ±10% adjustment range is not recommended.
External Input Open:
External Input Low:
Figure 4. Trim Connections Using a Trimpot
On/Off pin High = DC/DC converter Off
On/Off pin Low = DC/DC converter On
Figure 3. Driving The Power-Up With An External Pull-up Resistor
Output Overvoltage Protection
The HEN D12 Series output voltage is monitored. If the output voltage
rises to a level, which could be damaging to the load, the internal 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.
Figure 5. Trim Connections Using Fixed Resistors
Trim Equations
$/7. K7
Output Overcurrent Detection
Overloading the power converter's output for an extended time will invariably cause internal component temperatures to exceed their maximum
ratings and eventually lead to component failure. High-current-carrying
components such as inductors, FET's and diodes are at the highest risk.
HEN D12 Series DC/DC converters incorporate an output overcurrent detection and shutdown function that serves to protect both the power converter
and its load.
If the output current exceeds it maximum rating by typically 40% (35 Amps)
or if the output voltage drops to less than 98% of it original value, the HEN
Install either a fixed
trim-up resistor
or a fixed trim-down
resistor depending upon
desired output voltage.
50 K7
Note: Resistor values are in k. Accuracy of adjustment is subject to
tolerances of resistors and factory-adjusted, initial output accuracy.
VO = desired output voltage. VONOM = nominal output voltage.
MDC_HEN-D12.C02 Page 5 of 11
HEN D12 Models
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
Typical Performance Curves for HEN 1.2V Models
MDC_HEN-D12.C02 Page 6 of 11
HEN D12 Models
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
Typical Performance Curves for HEN 1.5V Models
Output Reverse Conduction
Many DC/DC's using synchronous rectification suffer from Output Reverse
Conduction. If those devices have a voltage applied across their output
before a voltage is applied to their input (this typically occurs when another
power supply starts before them in a power-sequenced application), they
will either fail to start or self destruct. In both cases, the cause is the
"freewheeling" or "catch" FET biasing itself on and effectively becoming a
short circuit.
HEN D12 DC/DC converters do not suffer from Output Reverse Conduction.
They employ proprietary gate drive circuitry that makes them immune to
applied output voltages.
MDC_HEN-D12.C02 Page 7 of 11
HEN D12 Models
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
Heatsink Installation
Heatsinks, in combination with adequate airflow, significantly extend the
power-handling capability of DATEL power supplies and add a safety
margin. Please study the Derating Curves to understand the increased
thermal capacity available when a heatsink is installed.
DATEL will supply our custom-designed heatsinks already installed. If
preferred, users may also purchase the heatsink assembly separately. If so,
please carefully follow the installation instructions below to avoid damage
to the DC/DC converter. Contact DATEL if you need assistance. The following procedures require adequate mechanical skills.
Installation has several goals:
1. Insure positive thermal contact between heat-generating circuit
components and the heatsink.
2. Avoid mechanical stress to the printed circuit board and on-board
3. Fasten the heatsink securely so that vibration in the application will not
loosen the mounting screws. Note that some heat may be conducted
through the screws.
Correct assembly requires a precision low range torque wrench.
[1] Make sure all the thermal pads have been securely installed. Mount the
heatsink using the screws supplied. See the assembly diagram. Do not
tighten the screws yet.
[2] Tighten the first screw only to 50% of maximum final torque (see the
table below).
[3] Tighten the screw in the diagonally opposite corner to 50% torque.
[4] Tighten the screw adjacent to the first screw to 50% torque.
[5] Repeat steps [2] to [4], tightening all screws to their maximum torque.
[6] Thoroughly retest the power supply before committing it to application.
WARNING: Incorrect assembly sequence and/or excessive torque may
damage the converter.
For attachment screws, the following maximum final torques must be used:
4. Avoid stripping threads in the aluminum heatsink.
Thermal Pads
The heatsink is supplied with one or more thermal mounting pads which
provide a heat transfer path with low thermal resistance between power
components and the heatsink. DATEL does NOT recommend "thermal
grease" or thermal mounting compounds.
Mounting Screws
DATEL power supplies are precision miniature electronic assemblies
fabricated on multiple circuit board layers. Excessive pressure or incorrect mechanical stress may distort the board layers, apply too much force
on components or even break small connections. Such fractures may not
be visible with the naked eye. It is very important to use the assembly
sequence below. We want both a correct sequence and the right amount
of torque. This assembly sequence is similar to engine cylinder heads
(progressive torquing of diagonally alternating bolts).
A tiny amount of medium-strength (blue) Loctite ® thread assembly adhesive or equivalent is acceptable in high vibration applications. The threads
must be degreased for Loctite to work. Do not soak the threads with
Loctite. Also, be aware that Loctite will soften at higher temperatures.
Screw Size
Maximum Assembled Torque
#2-56 thread
2.5 inch-pounds maximum
#4-40 thread
5.5 inch-pounds maximum
#M3 thread
6.0 inch-pounds maximum
#6-32 thread
9.6 inch-pounds maximum
*ˆ˜Ê£Ê œÌV…
MDC_HEN-D12.C02 Page 8 of 11
HEN D12 Models
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
Automated Assembly Production Notes
DATEL’s new high-efficiency DC/DC converters are designed for modern
surface-mount technology (SMT) automated assembly using screened
solder paste, "pick and place" component positioning and forced hot air
reflow oven soldering. If you are new to SMT techniques and have a volume
application, these features save time, cost and improve manufacturing
efficiency. DATEL’s DC/DC assembly operations themselves make extensive
use of such techniques.
Even if you have previous SMT experience, you should read the sections
below on solder reflow profiles and heat shields. This information is not
intended to replace the documentation for your SMT system. We assume
that you are already experienced with all the components of your SMT
This section will discuss several SMT issues, including:
I/O Mechanical Configuration
Part Handling and Supply
Printed Circuit Board (pcb) Mounting
Soldering using Reflow Technology
Temperature Profiling
them to the host pcb and accurately position them. The plastic heat shield
(see below) doubles as a vacuum pickup area.
If you are using the preinstalled heatsink from DATEL, proceed normally
with surface mounting per the information in this section (the heat shield
fits completely over the heatsink). However, if you wish to add the heatsink
after receiving the converters and heatsink separately, you must install the
heatsink before solder reflow. Essentially, install the heatsink then place
the assembled converters back in the tray for surface mount positioning.
Please observe the torquing and assembly procedure discussed earlier for
the heatsink.
Pick and Place pcb Mounting
The main issues here are pad area, orientation, positioning accuracy,
vacuum pickup and coplanarity. DATEL recommends that pcb pads to
interface with the DC/DC converter should be sized as shown in the diagram below. The pads footprint accommodates the positioning accuracy of
your SMT equipment and manufactured tolerances of the DC/DC mounting
Heat Shields and Removal
Mechanical Configuration of Input/Output Connections
These new converters are supplied either using traditional through-hole
pins or SMT leads. (Note that some models are offered only with lead
mounting). The pin options insert into plated-through holes in the host pcb.
Be aware that some heat dissipation is carried off by either the pins or
leads. The Derating Curves assume that some additional pad area is available on your host pcb to absorb the heat.
The lead option uses either short tabs in "gullwing" style or standoff leads
under the converter. The gullwing leads typically are copper alloy with 150
microinches of tin plating. Solder paste (typically 0.008" to 0.009" thick) is
applied to the host pcb using a solder mask pressure screening technique
and the board is heated and cooled long enough for the solder to reflow
and adhere to both the host pads and the converter’s mounting leads.
Figure 6. Recommended SMT Mounting Pad Dimensions
After such mounting, the entire mechanical mounting load is carried by the
solder. Obviously the converters must be accurately positioned all during
the solder reflow period. Where solder surface tension is sufficient to force
tiny components into position, these larger converters may not move and
must be accurately positioned by your SMT system.
Orientation: When loaded into JEDEC trays, these converters are all
oriented in the same direction. See the diagram below. For the LEN and
HEN series, a notch is placed on the top of the case (on the removal tabs) to
indicate the pin 1 position. You should visually inspect the tray to be sure of
this orientation.
Part Handling and Supply
On the bottom of the converter, the LEN and HEN series include optical
fiducial marks viewable by your SMT imaging system. See the attached
diagram. Observing from the bottom, your SMT imaging camera should find
these marks to identify the converter and verify pin 1. On most pick-andplace systems, during head transit, the imaging system will automatically
fine tune the end mounting position of the converter using image comparisons from these fiducials or other reference marks you have chosen.
SMT eighth- and quarter-brick DC/DC converters (plus installed heat
shields if used) are supplied in JEDEC-standard 5.35" by 12.4" waffle trays
which are compatible with the feeders on industry-standard pick-and-place
Since the converters are larger and heavier than many other components,
make sure your system can reliably remove the units from their trays, move
The fiducial marks are placed fairly close together because most imaging
systems have a one inch or less observing area since most SMT parts are
considerably smaller than these converters. You may prefer to train your
imaging system to use a corner of the converter or an I/O lead.
MDC_HEN-D12.C02 Page 9 of 11
HEN D12 Models
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
In the drawing below, these dimensions are intended for initial search for
these marks by your camera. There will be tiny variations in absolute position from unit to unit.
Figure 7. Fiducial Mark Location
If you use a camera above the pcb after placement on the solder paste, do
not rely on the inkjet marking on the heat shield to verify proper orientation.
Use the pin 1 notch instead.
Coplanarity: DATEL manufactures these converters with very flat mounting
leads (see coplanarity specs) however your host pcb must also be flat for a
successful mounting. Be aware of possible warping of the pcb under heat
gradients and/or humidity conditions. The solder paste will tolerate a small
amount of mismatch and will tend to “wet” the entire pad area by capillary
action if the temperatures are correct.
Vacuum Pickup: Select the vacuum collet on your SMT placement system
for the weight and size of the DC/DC converter. Note that units with
heatsinks are slightly heavier. Tests at DATEL have shown that excellent
acceleration and transit head speed are available for these converters if
the collet size is proper and the vacuum is sufficient. When positioning the
vacuum collet, use the geometric center of the heat shield as the pickup
area since the center of gravity is very close.
Reflow technology works well for small parts. However, larger components
such as these DC/DC’s with higher thermal mass may require additional
reflow time (but not enough to disturb smaller parts also being reflowed
concurrently with the DC/DC). When this is combined with higher temperature lead-free solders (or solders with reduced heavy metals), there is
increased risk of reheating components inside the DC/DC enough so that
they either change positions (and possibly stop functioning) or the components are damaged by the heat.
For these reasons, DATEL developed disposable heat shields using high
temperature plastic. The DC/DC is installed and reflowed with the shield in
place. After successful reflow and cooling, and before washing, the heat
shield should be removed.
Temperature Profiling
We wish to ramp the temperature up and down to successfully reflow the
solder without heat damage. Each reflow oven, humidity conditions, solder
paste type, oven feed rate, and the number of heat zones all require a different profile. Therefore you may have to experiment.
Since these converters are constructed using high temperature solders,
there will be no heat problems on your host pcb using traditional solder
with 63% lead and 37% tin with a melting point of +183°C. Device lead
temperature must remain below 230°C for less than 75 seconds, assuming
that the heat shield is in place. DATEL uses a 216°C melt lead-free tin/
silver/copper alloy to assemble these converters.
There are several lead-free solders suitable for your host pcb depending
on your SMT system and whatever local certification and environmental
regulations you must observe. Contact DATEL if you need specific advice.
Heat Shield
Careful thermocouple testing has shown that the interior of the DC/DC
under the heat shield is tens of degrees cooler than the outside ambient
temperature for typical reflow profiles. This protects internal components
and limits the amount of reflow where it is not desired. The heat shield also
includes marking for product identification and a date/lot code.
On LEN and HEN models, the heat shield is attached to the converter using
molded plastic pins on the heat shield interior which insert into recessed
dimples in the pinframe. An extra molded pin on the heat shield at the pin
1 location (and corresponding notch on the pcb) can only be installed one
way properly on the pinframe. If the shield accidentally comes loose, it may
be reinstalled by aligning the pins and dimples.
To remove the shield from the converter, after successful mounting and
cooling, squeeze the heat shield ears inward toward the converter body and
pull the shield upwards. Discard or recycle the shield. If you are using a flux
wash cycle, remove the heat shield before washing to avoid coming loose
inside the washer.
MDC_HEN-D12.C02 Page 10 of 11
HEN D12 Models
Single Output, Non Isolated, 12VIN, 0.8-5VOUT
25 Amp, High di/dt DC/DC Converters
Figure 8. Shipping Tray
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11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
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This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to:
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
© 2014 Murata Power Solutions, Inc.
MDC_HEN-D12.C02 Page 11 of 11