LSM Series D12 SMT's (surface-mount packages)
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. LSM D12
DC/DC's accept a 12V input (10.8V to 13.2V 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 10 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 (96% 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 over-
current detection, continuous short-circuit protec-
tion, 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 10 Amps at ambient temperatures to
+65°C with 100 lfm air fl ow.
If your new system boards call for three or
more 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 SMT's
will save you money.
Typical Unit
+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
FEATURES
Step-down, wide buck regulators for new
distributed 12V power architectures
12V input (10.8-13.2V range)
0.75 to 5VOUT @10A
Voltage-selectable "T" version
Non-isolated, fi xed-frequency,
synchronous-rectifi er topology
Tape and reel SMT package
±1.25% setpoint accuracy
Effi ciencies to 96% @ 10 Amps
Stable no-load operation
Remote on/off control
Sense pin and output voltage trim
No derating to +65°C with 100 lfm
UL/IEC/EN60950-1 certifi cation pending
EMC compliant
PRODUCT OVERVIEW
Typ
ica
l U
nit
NOT RECOMMENDED
FOR NEW DESIGNS
MDC_LSM 10A D12 Models.D02 Page 1 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com
www.murata-ps.com/support
For full details go to
www.murata-ps.com/rohs
➀ Typical at TA = +25°C under nominal line voltage and full-load conditions, unless 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 LSM-T/10-D12 specifi cations are given at VOUT = 5V, full load.
Maximum Rated Output
Current in Amps
Non-Isolated SMT
Output
Confi guration:
L = Unipolar
Low Voltage
Nominal Output Voltage:
0.8, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3, 5
Volts or "T" voltage selectable
Input Voltage:
D12 = 12V nominal
L SM 10-/D12-1.8 C
-
RoHS-6 compliant*
* Contact Murata Power Solutions
for availability.
PERFORMANCE SPECIFICATIONS SUMMARY AND ORDERING GUIDE ➀
Models
Output Input Effi ciency
Package
(Case,
Pinout)
VOUT
(Volts)
IOUT
(Amps)
R/N (mVp-p) ➁Regulation (Max.) ➂VIN Nom.
(Volts)
Range
(Volts)
IIN ➃
(mA/A)
Full Load ½ Load
Typ. Max. Line Load Min. Typ. Typ.
LSM-0.8/10-D12 0.8 10 45 60 ±0.1% ±0.375% 12 10.8-13.2 30/0.84 80.5% 82.5% 85% C45, P63
LSM-1/10-D12 1 10 50 75 ±0.1% ±0.25% 12 10.8-13.2 35/1.02 83% 85% 86% C45, P63
LSM-1.2/10-D12 1.2 10 50 85 ±0.2% ±0.65% 12 10.8-13.2 40/1.19 85% 87% 88% C45, P63
LSM-1.5/10-D12 1.5 10 50 75 ±0.1% ±0.25% 12 10.8-13.2 50/1.47 86.5% 88.5% 89.5% C45, P63
LSM-1.8/10-D12 1.8 10 50 75 ±0.1% ±0.25% 12 10.8-13.2 55/1.75 88% 90% 90.5% C45, P63
LSM-2/10-D12 2 10 50 75 ±0.1% ±0.25% 12 10.8-13.2 55/1.9 89% 91% 91.5% C45, P63
LSM-2.5/10-D12 2.5 10 50 75 ±0.1% ±0.25% 12 10.8-13.2 60/2.3 90% 92.5% 92% C45, P63
LSM-3.3/10-D12 3.3 10 50 75 ±0.1% ±0.7% 12 10.8-13.2 70/3 92% 94% 93.5% C45, P63
LSM-5/10-D12 5 10 75 100 ±0.3% ±0.95% 12 10.8-13.2 85/4.5 93.5% 96% 95.5% C45, P63
LSM-T/10-D12 0.75-5 10 50 75 ±0.1% ±0.25% 12 10-14 100/6.5 92% 93% -- C45, P63
PART NUMBER STRUCTURE
MDC_LSM 10A D12 Models.D02 Page 2 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
Pin Function P63
1 On/Off Control
2 +Input
3 Common
4 +Output
5 VOUT Trim
6 +Sense
I/O Connections
Case C45
3-4#/00%2,%!$3
#/0,!.!2
"/44/-6)%7
2%#/--%.$%$0!$,!9/54
490
490
%130
2ECOMMENDED0AD3IZEXX
%130
BOTTOMVIEW
1.36
(34.54)
0.375
(9.53)
0.112 TYP.
(2.84)
0.052
(1.32)
LSMWITH REMOVEABLE HEAT SHIELD
FOR HIGHTEMPERATURE SOLDER
CAUTION
PRESS TO REMOVE
THE HEAT SHIELD
AFTER THE SOLDER
PROCESS
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
Refer to the last page for
Tape and Reel information.
DIMENSIONS ARE IN INCHES (MM)
MECHANICAL SPECIFICATIONS
()
CAUTION
PRESS TO REMOVE
THE HEAT SHIELD
AFTER THE SOLDER
PROCESS
NOTCH IN SHELL
INDICATES PIN ONE
MDC_LSM 10A D12 Models.D02 Page 3 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
MDC
_
LSM
10
AD
12_
A
01
P
age 4 o
f
14
Input
Input Voltage Range See Ordering Guide
Input Current:
Normal Operating Conditions See Ordering Guide
Inrush Transient 0.08A2 sec
Standby/Off Mode 1.5mA
Output Short-Circuit Condition 12-40mA average (model dependent)
Input Refl ected Ripple Current ➁ ➅ 40mAp-p
Input Filter Type Capacitive
Overvoltage Protection None
Reverse-Polarity Protection None
Undervoltage Shutdown None (except 8V LSM-T/10-D12)
On/Off Control ➁ ➂ ➆ On = open (internal pull-up to +VIN)
Off = 0 to +0.4V (1mA max.)
Output
VOUT Accuracy (50% load) ±1.25% max. (±2% "T" version, 50% load)
Minimum Loading ➀ No load
Maximum Capacitive Load 1000µF (low ESR, OSCON)
VOUT Trim Range ➇ ±10% (0.8V not trimmable)
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: ➈
Current-Limiting Detection Point 17 Amps
Short-Circuit Detection Point 98% of VOUT set
SC Protection Technique Hiccup with auto recovery
Short-Circuit Current 120-400mA average (model dependent)
Dynamic Characteristics
Transient Response (50% load step) 115µsec to ±2% of fi nal value
Start-Up Time: ➁
VIN to VOUT and On/Off to VOUT 75msec for VOUT = 1V and 0.8V
50msec for VOUT = 1.2V to 5V
Switching Frequency:
0.8V, 1V/1.2V Models 105/120kHz ±10%
1.5V/1.8V, 2V Models 160/177kHz ±10%
2.5V, 3.3V, 5V Models 195kHz ±10%
LSM-T/10-D12 230kHz ±30kHz
Environmental
Calculated MTBF ➄ 2.3-1.8 million hours (1VOUT to 5VOUT)
Operating Temperature: (Ambient) ➁
Without Derating (100 lfm) –40 to +48/64°C (model dependent)
With Derating See Derating Curves
Thermal Shutdown +115°C (110 to 125°C)
Physical
Dimensions 1.3" x 0.53" x 0.34" (33.02 x 13.46 x 8.64 mm)
Pin Dimensions/Material 0.112" x 0.062" (2.84 x 1.57mm) rectangular
copper with gold plate over nickel underplate
Weight 0.28 ounces (7.8g)
Flamability Rating UL94V-0
EMI Conducted and radiated FCC part 15,
EN55022 (may require external fi lter)
Safety UL/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 or the application
of appropriate voltages (referenced to Common, pin 3). Applying a voltage to On/Off Control when
no input voltage is applied to the converter may cause permanent damage.
Input Voltage:
Continuous or transient 15 Volts
On/Off Control (Pin 1) +VIN (+4V for "T" version)
Input Reverse-Polarity Protection None
Output Overvoltage Protection None
Output Current Current limited. Devices can
withstand sustained output short
circuits without damage.
Storage Temperature –40 to +125°C
Lead Temperature See Refl ow Solder Profi le
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 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-qual-
ity, high-performance internal I/O caps, and will operate within spec in most
applications with no additional external components.
In particular, the LSM D12's 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/DC's 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.
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 5-20MHz bandwidth with an external 33µF input
capacitor and a simulated source impedance of 220µF and 12µH. See I/O Filtering, Input
Ripple Current and Output Noise for details.
➆ On/Off Control for LSM-T/10-D12 only: Positive Logic: On = pin open or to +4V max.,
Off = pin grounded or 0 to +0.4V max. Shutdown current is 3µA sink.
➇ The Output Voltage Range for the LSM-T/10-D12 is +0.75V to +5V, user selectable.
➈ LSM-T/10-D12 Overcurrent and Short-circuit specs:
Current limit 25 Amps
Short Circuit Current 600mA
TECHNICAL NOTES
MDC_LSM 10A D12 Models.D02 Page 4 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
Figure 3. Measuring Output Ripple/Noise (PARD)
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
#
).
6
).
#
"53
,
"53
#
).
§&%32M7 K(Z
#
"53
§&%32M7 K(Z
,
"53
§(
,3-4$&ILTERS
#
).
X§&#
"53
§&
,
"53
§(
).054
#/--/.
#522%.4
02/"%
4/
/3#),,/3#/0%
n
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.
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. LSM D12 Series DC/DC convert-
ers 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 20 Amps 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/DCs 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
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 volt-
age 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 pin6.
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
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.
MDC_LSM 10A D12 Models.D02 Page 5 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
).054
#/--/.
/./&&
#/.42/,
).054
#/--/.
%84%2.!,
/0%.
#/,,%#4/2
).054
K7
External Input Open: On/Off pin Low = DC/DC converter Off
External Input Low: On/Off pin High = DC/DC converter On
Figure 5. Driving the External Power-Up Open Collector
).054
§! 333$
07-
#/--/.
/./&&
#/.42/,
Figure 4A. LSM-T10-D12 Driving the On/Off Control Input
ON/OFF pin open: Logic High = DC/DC converter On
ON/OFF pin <0.4V: Logic Low = DC/DC converter Off
Figure 4. Driving the On/Off Control Pin with an Open-Collector Drive Circuit
(All models except LSM-T/10-D12)
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
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 resistor.
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.
Leaving the input of the external circuit open during power-up will have the
output of the DC/DC converter disabled. When the input to the external open
collector is pulled low, the DC/DC converters 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.
MDC_LSM 10A D12 Models.D02 Page 6 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
Figure 7. Trim Connections Using Fixed Resistors
Figure 6. Trim Connections Using a Trimpot
Trim Equations
UP VO – VO NOM
RT (kΩ) = 1.46
DOWN VO NOM – VO
RT (kΩ) = – X – X
1.82(VO – 0.8)
UP VO – VO NOM
RT (kΩ) = 3.72
DOWN VO NOM – VO
RT (kΩ) = – X – X
4.64(VO – 0.8)
UP VO – VO NOM
RT (kΩ) = 6
DOWN VO NOM – VO
RT (kΩ) = – X – X
7.5(VO – 0.8)
LSM-1/10-D12: X = 0.909
LSM-1.1/10-D12: X = 2.49
LSM-1.2/10-D12: X = 3.09
LSM-1.3/10-D12: X = 4.12
LSM-1.5/10-D12: X = 13.3
LSM-1.8/10-D12: X = 16.9
LSM-2/10-D12: X = 15.4
LSM-2.5/10-D12: X = 20
LSM-3.3/10-D12: X = 15
LSM-5/10-D12: X = 10
,/!$
K7
4U R N S
).054
#/--/.
#/--/.
/54054
42)-
Trim
Down
T
rim
Up
LOAD
+INPUT
COMMON
+OUTPUT
TRIM
COMMON
Note: Install either a fixed
trim-up resistor or a fixed
trim-down resistor depending
upon desired output voltage.
If the output current exceeds it maximum rating by typically 70% or if the
output voltage drops to less than 98% of it original value, the LSM D12's inter-
nal overcurrent-detection circuitry immediately turns off the converter, which
then goes into a "hiccup" mode. While hiccupping, the converter will continu-
ously attempt to restart itself, go into overcurrent, and then shut down. Once
the output short is removed, the converter will automatically restart itself.
Output Voltage Trimming (Except "T" models—See "T" Trimming)
Allowable trim ranges for each model in the LSM D12 SMT Series are ±10%.
The LSM-T/10-D12 has a user-selectable output range of +0.75V to +5V.
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.
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.
The following trim equations 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 adjustment range is not recommended.
When using trim in combination with Remote Sense, the maximum rated power
must not be exceeded (see Remote Sense).
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.
Note: LSM-0.8/10-D12 is not trimmable.
"T" Model, LSM-T/10-D12, Trimming
This version of the LSM 10A 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.
MDC_LSM 10A D12 Models.D02 Page 7 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
The resistor trim up equation for the LSM-T/10-D12 is as follows:
Where VO is the desired output voltage.
The LSM-T/10-D12 fi xed resistance values to set the output values are:
VOUT
(typ.) 0.7525 1.0 1.2 1.5 1.8 2 2.5 3.3 5.0
RTRIM
(kΩ)Open 41.424 22.46 13.05 9.024 7.417 5.009 3.122 1.472
CAUTION: To retain proper regulation, do not exceed the 5 Volt output.
Voltage Trim
The LSM-T/10-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 x (VO – 0.7525))
The LSM-T/10-D12 fi xed trim voltages to set the output voltage are:
VOUT
(typ.) 0.7525 1.0 1.2 1.5 1.8 2 2.5 3.3 5.0
VTRIM Open 0.68354 0.67 0.65 0.63 0.617 0.583 0.53 0.4166
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 SMT's 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.
RTRIMUP (Ω) = –1000
10500
VO – 0.7525
The highest temperatures in LSM D12 SMT's 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.
LSM-T/10-D12 thermal protection occurs at +125°C and restart at approxi-
mately +115°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.
Start Up Considerations
When power is fi rst applied to the DC/DC converter, operation is different than
when the converter is running and stabilized. There is some risk of start up
diffi culties if you do not observe several application features. Lower input volt-
age converters may have more problems here since they tend to have higher
input currents. Operation is most critical with any combination of the following
external factors:
1 - Low initial input line voltage and/or poor regulation of the input source.
2 – Full output load current on lower output voltage converters.
3 – Slow slew rate of input voltage.
4 – Longer distance to input voltage source and/or higher external input
source impedance.
5 - Limited or insuffi cient ground plane. External wiring that is too small.
6 – Too small external input capacitance. Too high ESR.
7 – High output capacitance causing a start up charge overcurrent surge.
8 – Output loads with excessive inductive reactance or constant current
characteristics.
If the input voltage is already at the low limit before power is applied, the
start up surge current may instantaneously reduce the voltage at the input
terminals to below the specifi ed minimum voltage. Even if this voltage depres-
sion is very brief, this may interfere with the on-board controller and possibly
cause a failed start. Or the converter may start but the input current load will
now drive the input voltage below its running low limit and the converter will
shut down.
MDC_LSM 10A D12 Models.D02 Page 8 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
If you measure the input voltage before start up with a Digital Voltmeter
(DVM), the voltage may appear to be adequate. Limited external capacitance
and/or too high a source impedance may cause a short downward spike at
power up, causing an instantaneous voltage drop. Use an oscilloscope not a
DVM to observe this spike. The converter’s soft-start controller is sensitive to
input voltage. What matters here is the actual voltage at the input terminals at
all times.
Symptoms of start-up diffi culties may include failed started, output oscilla-
tion or brief start up then overcurrent shutdown. Since the input voltage is never
absolutely constant, the converter may start up some times and not others.
Solutions
To improve start up, review the conditions above. One of the better solutions is
to place a moderate size capacitor very close to the input terminals. You may
need two parallel capacitors. A larger electrolytic or tantalum cap supplies the
surge current and a smaller parallel low-ESR ceramic cap gives low AC imped-
ance. Too large an electrolytic capacitor may have higher internal impedance
(ESR) and/or lower the start up slew rate enough to upset the DC/DC’s control-
ler. Make sure the capacitors can tolerate refl ected switching current pulses
from the converter.
The capacitors will not help if the input source has poor regulation. A
converter which starts successfully at 3.3 Volts will turn off if the input voltage
decays to below the input voltage theshold, regardless of external capacitance.
Increase the input start up voltage if possible to raise the downward voltage
spike. Also, make sure that the input voltage ramps up in a reasonably short
time (less than a few milliseconds). If possible, move the input source closer to
the converter to reduce ohmic losses in the input wiring. Remember that the
input current is carried both by the wiring and the ground plane return. Make
sure the ground plane uses adequate thickness copper. Run additional bus wire
if necessary.
Any added output capacitor should use just enough capacitance (and no
more) to reduce output noise at the load and to avoid marginal threshold noise
problems with external logic. An output cap will also “decouple” inductive reac-
tance in the load. Certain kinds of electronic loads include “constant current”
characteristics which destabilize the output with insuffi cient capacitance. If the
wiring to the eventual load is long, consider placing this decoupling cap at the
load. Use the Remote Sense input to avoid ohmic voltage drop errors.
An elegant solution to start up problems is to apply the input voltage with
the Remote On/Off control fi rst in the off setting (for those converters with an
On/Off Control). After the specifi ed start-up delay (usually under 20 mSec), turn
on the converter. The controller will have already been stabilized. The short
delay will not be noticed in most applications. Be aware of applications which
need “power management” (phased start up).
Finally, it is challenging to model some application circuits with absolute
fi delity. How low is the resistance of your ground plane? What is the inductance
(and distributed capacitance) of external wiring? Even a detailed mathematical
model may not get all aspects of your circuit. Therefore it is diffi cult to give cap
values which serve all applications. Some experimentation may be required.
Typical Performance Curves for LSM D12 SMT Series
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT #
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
n
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
!MBIENT4EMPERATUREo#
.ATURAL#ONVECTION
LFM
LFM
MDC_LSM 10A D12 Models.D02 Page 9 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT #
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
n
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
!MBIENT4EMPERATUREo#
.ATURAL#ONVECTION
LFM
LFM
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT #
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
n
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
!MBIENT4EM
P
ERATURE
o#
.ATURAL#ONVECTION
LFM
LFM
Typical Performance Curves for LSM D12 SMT Series
MDC_LSM 10A D12 Models.D02 Page 10 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT #
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT #
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
Typical Performance Curves for LSM D12 SMT Series
n
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
!MBIENT4EM
P
ERATURE
o#
.ATURAL#ONVECTION
LFM
LFM
n
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
!MBIENT4EM
P
ERATURE
o#
.ATURAL#ONVECTION
LFM
LFM
MDC_LSM 10A D12 Models.D02 Page 11 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT #
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
n
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
!MBIENT4EM
P
ERATURE
o#
.ATURAL#ONVECTION
LFM
LFM
Typical Performance Curves for LSM D12 SMT Series
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT #
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
n
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
!MBIENT4EM
P
ERATURE
o#
.ATURAL#ONVECTION
LFM
LFM
MDC_LSM 10A D12 Models.D02 Page 12 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT #
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
Typical Performance Curves for LSM D12 SMT Series
n
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
!MBIENT4EMPERATUREo#
.ATURAL#ONVECTION
LFM
LFM
n
,3-4$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
6/546TRANSVERSEAIRFLOW
/UTPUT#URRENT!MPS
!MBIENT4EMPERATUREo#
.ATURAL#ONVECTION
LFM
LFM
LFM
LFM
,3-4$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT #6/546
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
MDC_LSM 10A D12 Models.D02 Page 13 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
Typical Performance Curves for LSM D12 SMT Series
Start-Up from ON/OFF
(VIN = 12V, IOUT = 5V/10A, COUT = 22µF)
10msec/div
VIN
5V/div
VOUT
2V/div
Start-Up from ON/OFF
(VIN = 12V, IOUT = 0.8V/10A, COUT = 22µF)
10msec/div
VIN
5V/div
VOUT
1V/div
Start-Up from VIN
(VIN = 12V, IOUT = 5V/10A, COUT = 22µF)
10msec/div
VIN
5V/div
VOUT
2V/div
Start-Up from VIN
(VIN = 12V, IOUT = 0.8V/10A, COUT = 22µF)
10msec/div
VIN
5V/div
VOUT
1V/div
MDC_LSM 10A D12 Models.D02 Page 14 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
Output Hiccup
(LSM-5/10-D12 Shorted VOUT, VIN = 12V)
20msec/div
100mV/div
Input Reflected Ripple Current
(Input Filter = 220µF/12µH/33µF, VIN = 12V, IOUT = 5V/10A)
2µsec/div
50mA/div
Output Ripple and Noise
(VIN = 12V, VOUT = 5V/10A, COUT= 22µF)
2µsec/div
20mV/div
Output Ripple and Noise
(VIN = 12V, VOUT = 0.8V/10A, COUT = 22µF)
2µsec/div
20mV/div
Typical Performance Curves for LSM D12 SMT Series
MDC_LSM 10A D12 Models.D02 Page 15 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
www.murata-ps.com/support
Typical Performance Curves for LSM D12 SMT Series
Dynamic Load Response
(VIN = 12V, VOUT = 5V, 5 to 10A Step, CO = 22µF + 1000µF Oscon)
100µsec/div
100mV/div
Dynamic Load Response
(VIN = 12V, VOUT = 0.8V, 5 to 10A Step, COUT= 22µF)
100µsec/div
100mV/div
Dynamic Load Response
(VIN = 12V, VOUT = 5V, 0 to 10A Step, CO = 22µF + 1000µF Oscon)
100µsec/div
100mV/div
Dynamic Load Response
(VIN = 12V, VOUT = 5V, 0 to 10A Step, COUT = 22µF)
100µsec/div
200mV/div
MDC_LSM 10A D12 Models.D02 Page 16 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
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 (10A) SMT DC/DC's 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 +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 limita-
tions, 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 compro-
mise 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. We do have a simple and practical, straightforward
approach that works. We assemble our SMT DC/DC’s on a thermally-stable
plastic lead-frame (nylon 46, UL94V-0 fl ammability rated) using a high temper-
ature lead-free solder. In addition, the LSM is transitioning to RoHS (Reduction
of Hazardous Substances) construction and SAC 305 RoHS-approved solder.
The lead-frame ensures coplanarity (to within 0.004 in.) 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, with a cutaway exposing the package leads,
provides thermal insulation to internal components during refl ow and doubles
as the vacuum pick-up location. 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 exceeding 2 minutes above 221°C are easily achieved. MPS's
new-generation SMT units are shipped in stackable, JEDEC-style plastic tray.
MDC_LSM 10A D12 Models.D02 Page 17 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
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
Murata Power Solutions' 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
MDC_LSM 10A D12 Models.D02 Page 18 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
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/
