FEATURES
Step-down buck regulators for new
distributed 12V power architectures
12V input (10-14V range)
0.75/1/1.2/1.5/1.8/2/2.5/3.3/5VOUT @16A
Non-isolated, fi xed-frequency,
synchronous-rectifi er topology
Tape and reel SMT package
±1.25% setpoint accuracy
Effi ciencies to 96% @ 16 Amps
Noise as low as 50mVp-p
Stable no-load operation
Remote on/off control
Sense pin and output voltage trim
No derating to +65°C with 200 lfm
Designed to meet UL/IEC/EN60950-1
safety
EMC compliant
+INPUT
(2)
COMMON
(3)
PWM
CONTROLLER
CURRENT
SENSE
REFERENCE &
ERROR AMP
V
CC
ON/OFF
CONTROL
(1)
V
OUT
TRIM
(5)
+OUTPUT
(4)
+SENSE
(6)
COMMON
(3)
Figure 1. Simplifi ed Schematic
Typical topology is shown
Typical Unit
LSM Series D12 SMTs (surface-mount pack-
ages) are ideal building blocks for emerging,
on-board power-distribution schemes in which
isolated 12V buses deliver power to any num-
ber of non-isolated, step-down buck regulators.
LSM D12 DC/DC’s accept a 12V input (10V to
14V input range) and convert it, with the highest
effi ciency in the smallest space, to a 0.75, 1,
1.2, 1.5, 1.8, 2, 2.5, 3.3 or 5 Volt output fully
rated at 16 Amps.
LSM D12’s are ideal point-of-use/load power
processors. They typically require no external
components. Their surface-mount packages
occupy a mere 1.3" x 0.53" (33.0 x 13.5mm),
and are only 0.34 inches (8.6mm) high.
The LSM’s best-in-class power density
is achieved with a fully synchronous, fi xed-
frequency, buck topology that also delivers:
high effi ciency (95% for 5VOUT models), low
noise (50mVp-p typ.), tight line/load regulation
(±0.1%/±0.25% max.), quick step response
(100μsec), stable no-load operation, and no
output reverse conduction.
The fully functional LSM’s feature output
overcurrent detection, continuous short-circuit
protection, over-temperature protection, a
remote on/off control pin (pull low to disable),
an output-voltage trim function, and a sense
pin. High effi ciency enables the LSM D12’s to
deliver rated output currents of 16 Amps at
ambient temperatures to +65°C with 100 lfm
air fl ow.
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,
Murata Power Solutions’ non-isolated LSM D12
SMTs will save you money.
PRODUCT OVERVIEW
NOT RECOMMENDED
FOR NEW DESIGNS
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 1 of 12
www.murata-ps.com
www.murata-ps.com/support
For full details go to
www.murata-ps.com/rohs
ORDERING GUIDE
Models
Output Input Effi ciency (Full Load)
Package
(Case,
Pinout)
VOUT
(Volts)
IOUT
(Amps)
R/N (mVp-p) ➁Regulation (Max.) ➂VIN Nom.
(Volts)
Range
(Volts)
IIN ➃
(mA/A)
VIN = nom. VIN = min
Typ. Max. Line Load Min. Typ. Typ.
LSM-0.75/16-D12 0.75 16 50 75 ±0.1% ±0.375% 12 10-14 35/1.26 83% 85% 86% C45, P63
LSM-1/16-D12 1 16 50 75 ±0.1% ±0.25% 12 10-14 35/1.57 83% 85% 86% C45, P63
LSM-1.2/16-D12 1.2 16 50 75 ±0.1% ±0.25% 12 10-14 40/1.84 85% 87% 88% C45, P63
LSM-1.5/16-D12 1.5 16 50 75 ±0.1% ±0.25% 12 10-14 50/2.26 86.5% 88.5% 89.5% C45, P63
LSM-1.8/16-D12 1.8 16 50 75 ±0.1% ±0.25% 12 10-14 55/2.67 88% 90% 91% C45, P63
LSM-2/16-D12 2 16 50 75 ±0.1% ±0.25% 12 10-14 55/2.93 89% 91% 91.5% C45, P63
LSM-2.5/16-D12 2.5 16 50 75 ±0.1% ±0.25% 12 10-14 75/368 88.5% 90.5% 91.5% C45, P63
LSM-3.3/16-D12 3.3 16 50 75 ±0.1% ±0.25% 12 10-14 70/4.68 92% 94% 94.5% C45, P63
LSM-5/16-D12 5 16 75 100 ±0.1% ±0.25% 12 10-14 85/7.06 92.5% 94.5% 95.5% C45, P63
LSM-T/16-D12 0.75-5 16 50 75 ±0.1% ±0.25% 12 10-14 85/7.02 93% 95% 95.5% C45, P63
Pin Function P63
1 On/Off Control
2 +Input
3 Common
4 +Output
5 VOUT Tr im
6 +Sense
I/O Connections
➀ Typical at TA = +25°C under nominal line voltage and full-load conditions, 200 lfm air fl ow for
extended operation, unless otherwise noted. All models are tested and specifi ed with external
22µF tantalum input and output capacitors. These capacitors are necessary to accommodate our
test equipment and may not be required to achieve specifi ed performance in your applications.
See I/O Filtering and Noise Reduction.
➁ Ripple/Noise (R/N) is tested/specifi ed over a 20MHz bandwidth and may be reduced with external
fi ltering. 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 specifi cations 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 RoHS6 compliance does not claim EU RoHS exemption 7b–lead in solder.
Performance Specifi cations and Ordering Guide ➀
Case C45
0.34
(8.64)
0.53
(13.46)
0.48
(12.19)
0.430
(10.92)
0.405
(10.29)
0.085
(2.16)
1.30
(33.02)
SMT COPPER LEADS
COPLANAR 0.004
1.177
(29.90)
0.310
(7.87)
0.048
(1.22)
0.075
(1.91)
BOTTOM VIEW
RECOMMENDED PAD LAYOUT
0.05
(1.27)
0.062
(1.57)
TYP.
0.112
(2.84)
TYP.
0.570 (14.48)
3 EQ. SP. @
0.190 (4.83)
0.310
(7.87)
Recommended Pad Size: 0.15 x 0.10 (3.81 x 2.54)
0.297
(7.54)
0.570 (14.48)
3 EQ. SP. @
0.190 (4.83)
2
2
3 4 5 6
6 5 4 3
1
1
Maximum Rated Output
Current in Amps
Non-Isolated SMT
Output
Confi guration:
L = Unipolar
Low Voltage
Nominal Output Voltage:
0.75, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3 or 5 Volts
Input Voltage Range:
D12 = 10 to 14 Volts
(12V nominal)
L SM 16-/D12-1.8
1.36
(34.54)
0.375
(9.53)
0.112 T Y P.
(2.84)
0.052
(1.32)
0.60
(15.24)
0.049
(1.24)
0.310
(7.87)
0.010
(0.254)
0.55
(13.97)
0.052
(1.32)
0.062
(1.57)
0.047
(1.19)
0.570 (14.48)
3EQ.SP.@
0.190 (4.83)
2
3456
1
NOTCH IN SHELL
INDICATES PIN ONE
CAUTION
PRESS TO REMOVE
THE HEAT SHIELD
AFTER THE SOLDER
PROCESS
NOTCH IN SHELL
INDICATES PIN ONE
LSM WITH REMOVABLE HEAT SHIELD
FOR HIGH TEMPERATURE SOLDER
BOTTOM VIEW
Note: Not all model number combinations
are available. Contact MPS.
-
RoHS6 hazardous substance
compliant*➄
C
* Contact Murata Power Solutions for
availability.
Part Number Structure Mechanical Specifications
Third Angle Projection
Dimensions are in inches (mm) shown for ref. only.
Components are shown for reference only.
Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 2˚
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 2 of 12
www.murata-ps.com/support
Input
Input Voltage Range 10-14 Volts (12V nominal)
Startup Voltage 8.5-9.2 Volts (model dependent)
Input Current:
Normal Operating Conditions See Ordering Guide
Inrush Transient 0.08A2 sec
Standby/Off Mode 1.5mA
Output Short-Circuit Condition ➁ 12-40mA average (model dependent)
Input Refl ected Ripple Current ➁ ➅ 20-50mAp-p, model dependent
Input Filter Type Capacitive
Overvoltage Protection None
Reverse-Polarity Protection None
Undervoltage Shutdown 7.5-8 Volts (model dependent)
On/Off Control ➁ ➂ On = open lead
Off = -0.3V to +0.2V (3µA max.)
Output
VOUT Accuracy (50% load) ±1.25%
Minimum Loading ➀ No load
Maximum Capacitive Load 1000µF (low ESR, OSCON)
VOUT Trim Range ±10%
Ripple/Noise (20MHz BW) ➀ ➁ ➃
See Ordering Guide
Total Accuracy 3% over line/load/temperature
Effi ciency See Ordering Guide
Overcurrent Detection and Short-Circuit Protection: ➁
Current-Limiting Detection Point 21-37 Amps (model dependent)
Short-Circuit Detection Point 98% of VOUT set
SC Protection Technique Hiccup with auto recovery
Short-Circuit Current 125-420mA average (model dependent)
Dynamic Characteristics
Transient Response (50% load step) 30-135µsec to ±2% of fi nal value
(model dependent)
Start-Up Time: ➁
VIN to VOUT and On/Off to VOUT 60msec for VOUT = 1V and 0.75V
40msec for VOUT = 1.2V to 5V
Switching Frequency 260kHz ±10%
Environmental
Calculated MTBF ➄
LSM-1.2/16-D12 9,160,138 hours
LSM-1.5/16-D12 8,674,318 hours
LSM-1.8/16-D12 8,334,117 hours
LSM-2.5/16-D12 8,534,580 hours
LSM-3.3/16-D12 7,817,255 hours
LSM-5/16-D12 7,756,061 hours
Operating Temperature: (Ambient) ➁ –40 to +85°C (with Derating)
See Derating Curves
Thermal Shutdown +115°C (110 to 125°C)
Physical
Dimensions 1.3" x 0.53" x 0.34" (33.03 x 13.46 x 8.64)
Lead Dimensions/Material 0.112" x 0.062" (2.84 x 1.57mm) rectangular
copper alloy with gold plate over nickel
underplate
Weight 0.28 ounces (7.8g)
Flamability Rating UL94V-0
Safety Designed to meetUL/cUL/IEC/EN 60950-1,
CSA-C22.2 No. 234
Performance/Functional Specifi cations
Typical @ TA = +25°C under nominal line voltage and full-load conditions unless noted. ➀
➀ All models are tested and specifi ed with external 22µF tantalum input and output capacitors.These
capacitors are necessary to accommodate our test equipment and may not be required to achieve
specifi ed performance in your applications. All models are stable and regulate within spec under
no-load conditions.
➁ See Technical Notes and Performance Curves for details.
➂ The On/Off Control (pin 1) is designed to be driven with open-collector logic (referenced to Common,
pin 3) or a switch to ground.
➃ Output noise may be further reduced with the installation of additional external output fi ltering. See
I/O Filtering and Noise Reduction.
➄ MTBF’s are calculated using Telcordia SR-332(Bellcore), ground fi xed, Ta = +25°C, full power,
natural convection, +67°C pcb temperature.
➅ Input Ripple Current is tested/specifi ed over a 5Hz-20MHz bandwidth with an external 2 x 100µF
input capacitor and a simulated source impedance of 1000µF and 1µH. See I/O Filtering, Input
Ripple Current and Output Noise for details.
Input Voltage:
Continuous or transient 15 Volts
On/Off Control (Pin 1) +6V
Input Reverse-Polarity Protection None
Output Overvoltage Protection None
Output Current Current limited. Devices can
withstand sustained output short
circuits without damage.
Storage Temperature –55 to +125°C
Lead Temperature See Refl ow Solder Profi le
These are stress ratings. Exposure of devices to greater than any of these conditions may
adversely affect long-term reliability. Proper operation under conditions other than those
listed in the Performance/Functional Specifi cations Table is not implied.
Absolute Maximum Ratings
I/O Filtering and Noise Reduction
All models in the LSM D12 Series are tested and specifi ed with external 22μF
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 LSM 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 LSM D12s input capacitors are specifi ed for low ESR and
are fully rated to handle the units’ input ripple currents. Similarly, the internal
output capacitors are specifi ed for low ESR and full-range frequency response.
As shown in the Performance Curves, removal of the external 22μF tantalum
output caps has minimal effect on output noise.
In critical applications, input/output ripple/noise may be further reduced using
fi ltering techniques, the simplest being the installation of external I/O caps.
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 appropri-
ate frequencies), low ESR, and high rms-ripple-current ratings. The switching
nature of modern DC/DCs requires that the dc input voltage source have low
ac impedance at the frequencies of interest. Highly inductive source imped-
ances can greatly affect system stability. Your specifi c system confi guration
may necessitate additional considerations.
Technical Notes
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 3 of 12
www.murata-ps.com/support
C1
C1 = NA
C2 = 22µF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE
C2 R
LOAD
6
4
COPPER STRIP
3
COPPER STRIP
SCOPE
+OUTPUT
COMMON
+SENSE
#
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6
).
#
"53
,
"53
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,
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Figure 2. Measuring Input Ripple Current
Output ripple/noise (also referred to as periodic and random deviations or
PARD) may be reduced below specifi ed limits with the installation of additional
external output capacitors. Output capacitors function as true fi lter elements
and should be selected for bulk capacitance, low ESR, and appropriate fre-
quency 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.
Figure 3. Measuring Input Ripple Current
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 func-
tion 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
fi ltering to meet your specifi c requirements. Contact our Applications Engineer-
ing Group for additional details.
Input Fusing
Most applications and or safety agencies require the installation of fuses at
the inputs of power conversion components. The LSM D12 Series are not
internally fused. Therefore, if input fusing is mandatory, either a normal-blow or
a fast-blow fuse with a value no greater than twice the maximum input current
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
slow-blow fuse with a typical value of about twice the maximum input current,
calculated at low line with the converters minimum effi ciency.
Safety Considerations
LSM D12 SMT's are non-isolated DC/DC converters. In general, all DC/DC's
must be installed, including considerations for I/O voltages and spacing/sepa-
ration requirements, in compliance with relevant safety-agency specifi cations
(usually UL/IEC/EN60950-1).
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.
Input Overvoltage and Reverse-Polarity Protection
LSM D12 SMT Series DC/DC's do not incorporate either input overvoltage or
input reverse-polarity protection. Input voltages in excess of the specifi ed
absolute maximum ratings and input polarity reversals of longer than "instan-
taneous" duration can cause permanent damage to these devices.
Start-Up Time
The VIN to VOUT Start-Up Time is the interval between the time at which a ramp-
ing input voltage crosses the lower limit of the specifi ed input voltage range
(10 Volts) and the fully loaded output voltage enters and remains within its
specifi ed accuracy band. Actual measured times will vary with input source
impedance, external input capacitance, and the slew rate and fi nal value of the
input voltage as it appears to the converter.
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 specifi cation defi nes the interval between the time at which the converter
is turned on and the fully loaded output voltage enters and remains within its
specifi ed accuracy band. See Typical Performance Curves.
Remote Sense
LSM D12 SMT Series DC/DC converters offer an output sense function on pin 6.
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 conse-
quently 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 cur-
rent 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 LSM's specifi ed rating. Therefore:
(VOUT at pins) x (IOUT) ≤ rated output power
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 4 of 12
www.murata-ps.com/support
The internal 10.5Ω resistor between +Sense and +Output (see Figure 1)
serves to protect the sense function by limiting the output current fl owing
through the sense line if the main output is disconnected. It also prevents
output voltage runaway if the sense connection is disconnected.
Note: If the sense function is not used for remote regulation, +Sense (pin 6)
must be tied to +Output (pin 4) at the DC/DC converter pins.
On/Off Control
The On/Off Control pin may be used for remote on/off operation. LSM D12
Series DC/DC converters are designed so that they are enabled when the con-
trol pin is left open (open collector) and disabled when the control pin is pulled
low (to less than +0.4V relative to Common). As shown in Figure 4, all models
have an internal pull-up current source to VIN (+Input).
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Figure 4. On/Off Control Using An External Open Collector Driver
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.
Applying an external voltage to the On/Off Control pin when no input power
is applied to the converter can cause permanent damage to the converter. The
on/off control function, however, is designed such that the converter can be
disabled (control pin pulled low) while input voltage is ramping up and then
"released" once the input has stabilized (see also power-up sequencing).
Power-up sequencing
If a controlled start-up of one or more LSM 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 driven with an external open collector
device as per Figure 5.
Figure 5. Driving The External Power-Up Open Collector
Leaving the input of the on/off circuit closed during power-up will have the
output of the DC/DC converter disabled. When the input to the external open
collector is pulled high, the DC/DC converter's output will be enabled.
Output Overvoltage Protection
LSM D12 SMT Series DC/DC converters do not incorporate output overvoltage
protection. In the extremely rare situation in which the device’s feedback loop
is broken, the output voltage may run to excessively high levels (VOUT = VIN). If it
is absolutely imperative that you protect your load against any and all possible
overvoltage situations, voltage limiting circuitry must be provided external to
the power converter.
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. LSM D12 SMT 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 70% (27 Amps)
or if the output voltage drops to less than 98% of it original value, the LSM
D12's internal overcurrent-detection circuitry immediately turns off the con-
verter, 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, the average output current will be approximately
400mA, and the average input current will be approximately 40mA. Once the
output short is removed, the converter will automatically restart itself.
Output Voltage Trimming
Allowable trim ranges for each model in the LSM D12 SMT Series are ±10%.
Trimming is accomplished with either a trimpot or a single fi xed resistor. The
trimpot should be connected between +Output and Common with its wiper
connected to the Trim pin as shown in Figure 6 below.
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Figure 6. Trim Connections Using a Trimpot
A trimpot can be used to determine the value of a single fi xed resistor
which can then be connected, as shown in Figure 7, 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.
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 5 of 12
www.murata-ps.com/support
Where VO is the desired output voltage.
The LSM-T/16-D12 fi xed resistance values to set the output values are:
VO0.7525V 1.0V 1.2V 1.5V 1.8V 2.5V 3.3V 5.0V
RT (kΩ)Open 41.424 22.46 13.05 9.024 5.009 3.122 1.472
CAUTION: To retain proper regulation, do not exceed the 5 Volt output.
Voltage Trim
The LSM-T/16-D12 may also be trimmed using an external voltage applied
between the Trim Input and Output Common. Be aware that the internal “load”
impedance looking into trim pin is approximately 5kΩ. Therefore, you may
have to compensate for this in the source resistance of your external voltage
reference.
The equation for this voltage adjustment is:
V
TRIM = 0.7 – (0.0667 × (VO – 0.7525))
The LSM-T/16-D12 fi xed trim voltages to set the output voltage are:
VO0.7525V 1.0V 1.2V 1.5V 1.8V 2.5V 3.3V 5.0V
VT (V) Open 0.6835 0.670 0.650 0.630 0.583 0.530 0.4166
Tr i m
Down
Tr i m
Up
LOAD
+INPUT
COMMON
+OUTPUT
TRIM
COMMON
Where: VO = Desired Output Voltage
VO NOM = Nominal Output Voltage
UP VO – VO NOM
RT (k7) = 5.509 – X
DOWN VO NOM – VO
RT (k7) = – X
7.87(VO – 0.7)
LSM-0.75/16-D12: X = 0.909
LSM-1/16-D12: X = 11.5
LSM-1.2/16-D12: X = 19.1
LSM-1.5/16-D12: X = 27.4
LSM-1.8/16-D12: X = 16.9
LSM-2/16-D12: X = 21.5
LSM-2.5/16-D12: X = 18.2
LSM-3.3/16-D12: X = 13.7
LSM-5/16-D12: X = 9.09
“T” Model LSM-T/16-D12
This version of the LSM 16A series offers a special output voltage trimming
feature which is fully compatible with competitive units. The output voltage
may be varied from 0.75 to 5 Volts using a single external trim-up resistor con-
nected from the Trim input to Output Common. If no trim resistor is attached
(Trim pin open), the output is 0.7525 Volts.
The trim may also be adjusted using an external reference voltage con-
nected to the Trim input.
As with other trim adjustments, use a 1% metal fi lm precision resistor with
low temperature coeffi cient (±100 ppm/°C or less) mounted close to the con-
verter with short leads. Also be aware that the output accuracy is ±2% (typical)
therefore you may need to vary this resistance slightly to achieve your desired
output setting.
The resistor trim up equation for the LSM-T/16-D12 is as follows:
Figure 7. Trim Connections Using Fixed Resistors
The equations below can be starting points for selecting specifi c trim-resistor
values. Recall, untrimmed devices are guaranteed to be ±1.25% accurate.
Adjustment beyond the specifi ed ±10% adjustment range is not recom-
mended. When using trim in combination with Remote Sense, the maximum
rated power must not be exceeded (see Remote Sense).
Trim Equations
Note: Resistor values are in kΩ. Accuracy of adjustment is subject
to tolerances of resistors and factory-adjusted, initial output accuracy.
VO = desired output voltage. VONOM = nominal output voltage.
UP VO – 0.7525
RT (7) = 10500 – 1000
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 6 of 12
www.murata-ps.com/support
Output Reverse Conduction
Many DC/DCs using synchronous rectifi cation 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.
LSM D12 SMT DC/DC converters do not suffer from Output Reverse Conduc-
tion. They employ proprietary gate drive circuitry that makes them immune to
applied output voltages.
Thermal Considerations and Thermal Protection
The typical output-current thermal-derating curves shown below enable
designers to determine how much current they can reliably derive from each
model of the LSM D12 SMTs under known ambient-temperature and air-fl ow
conditions. Similarly, the curves indicate how much air fl ow is required to reli-
ably deliver a specifi c output current at known temperatures.
The highest temperatures in LSM D12 SMTs occur at their output inductor,
whose heat is generated primarily by I2R losses. The derating curves were
developed using thermocouples to monitor the inductor temperature and vary-
ing the load to keep that temperature below +110°C under the assorted condi-
tions of air fl ow and air temperature. Once the temperature exceeds +115°C
(approx.), the thermal protection will disable the converter. Automatic restart
occurs after the temperature has dropped below +110°C.
As you may deduce from the derating curves and observe in the effi ciency
curves on the following pages, LSM D12 SMT's maintain virtually constant
effi ciency from half to full load, and consequently deliver very impressive
temperature performance even if operating at full load.
Lastly, when LSM D12 SMT's are installed in system boards, they are
obviously subject to numerous factors and tolerances not taken into account
here. If you are attempting to extract the most current out of these units under
demanding temperature conditions, we advise you to monitor the output-
inductor temperature to ensure it remains below +110°C at all times.
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 7 of 12
www.murata-ps.com/support
Typical Performance Curves for LSM D12 SMT Series
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT #
,OAD#URRENT!MPS
%FFICIENCY
6
).
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72
74
76
78
80
82
84
86
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12345678910 11 12 13 14 15 16
LSM-1/16-D12
Efficiency vs. Line Voltage and Load Current @ 25°C
Load Current (Amps)
Efficiency (%)
V
IN
= 10V
V
IN
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V
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LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 8 of 12
www.murata-ps.com/support
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Typical Performance Curves for LSM D12 SMT Series
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 9 of 12
www.murata-ps.com/support
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Typical Performance Curves for LSM D12 SMT Series
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 10 of 12
www.murata-ps.com/support
Figure 6. Refl ow Solder Profi le
HEAT SHIELD OUTSIDE TEMPERATURE
Sn96.5/Ag3.5 Melting Point
Sn63/Pb37 Melting Point
250
200
150
100
50
0 50 100 150 200 250 300 350 400
221
183
PCB TEMPERATURE INSIDE THE HEAT SHIELD
Temperature (˚C)
Time
(
Seconds
)
Tape & Reel Surface Mount Package
Murata Power Solutions’ LSM series DC/DC converters are the only higher-
current (16A) SMT DC/DCs that can be automatically “pick-and-placed” using
standard vacuum-pickup equipment (nozzle size and style, vacuum pressure
and placement speed may need to be optimized for automated pick and place)
and subsequently refl owed using high-temperature, lead-free solder.
Virtually all SMT DC/DCs today are unprotected “open-frame” devices
assembled by their vendors with high-temperature solder (usually Sn96.5/
Ag3.5 with a melting point of +221°C) so that you may attach them to your
board using low-temperature solder (usually Sn63/Pb37 with a melting point
of +183°C). Conceptually straightforward, this “stepped” solder approach has
its limitations, and it is clearly out of step with an industry trending toward
the broad use of lead-free solders. Are you to experiment and develop refl ow
profi les from other vendors that ensure the components on those DC/DC never
exceed 215–216°C? If those components get too hot, “double-refl ow” could
compromise the reliability of their solder joints. Virtually all these devices
demand you “cool down” the Sn63 profi le you are likely using today.
MPS is not exempted from the Laws of Physics, and we do not have magic
solders no one else has. Nevertheless, we have a simple and practical, straight-
forward approach that works. We assemble our LSM SMT DC/DCs using a
high-temperature (+216°C), lead-free alloy (Sn96.2%, Ag2.5%, Cu0.8%,
Sb0.5%). The LSM design ensures co-planarity to within 0.004 inches (100μm)
of the unit’s copper leads. These leads are gold-plated with a nickel underplate.
See Mechanical Data for additional information.
The disposable heat shield (patent pending), which has a cutaway expos-
ing the package leads, provides thermal insulation to internal components
during refl ow and its smooth surface ideally doubles as the vacuum pick-up
location also. The insulation properties of the heat shield are so effective that
temperature differentials as high as 50°C develop inside-to-outside the shield.
Oven temperature profi les with peaks of 250–260°C and dwell times exceed-
ing 2 minutes above 221°C (the melting point of Sn96.5/Ag3.5) are easily
achieved.
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 11 of 12
www.murata-ps.com/support
0.51(13.0)
7.38 (187.5)
13.0 (330.2)
2.44
(62.0)
Figure 8. Reel Dimensions
DATEL’s new-generation LSM SMT DC/DC converters are shipped in quantities of 150 modules per tape and reel.
Figure 7. Tape Dimensions
CAUTION
PRESS TO REMOVE
THE HEAT SHIELD
AFTER THE SOLDER
PROCESS.
NOTCH IN SHELL
INDICATES
PIN ONE.
0.158
(4) CENTERED
PICK UP
LOCATION
2.205
(56)
2.063
(52.4)
FEED
DIRECTION
1.370
(34.8)
1.102
(28)
0.605
(15.36)
TA P E
0.590
(14.97)
DIMENSIONS
IN INCHES (mm)
111
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
MDC_LSM 16A D12 Models.A06 Page 12 of 12
www.murata-ps.com/support
Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifi cations are subject to change without
notice. © 2013 Murata Power Solutions, Inc.
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to: http://www.murata-ps.com/requirements/
