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LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Typical Unit
FEATURES
Step-down buck regulators for new
distributed 12V power architectures
12V input (10-14V range)
0.75/1/1.2/1.5/1.8/2/2.5/3.3/5V
OUT
@16A
Non-isolated, fixed-frequency,
synchronous-rectifier topology
Tape and reel SMT package
±1.25% setpoint accuracy
Efficiencies 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
PRODUCT OVERVIEW
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
efficiency 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, fixed-
frequency, buck topology that also delivers:
high efficiency (95% for 5V
OUT
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 efficiency enables the LSM D12’s to
deliver rated output currents of 16 Amps at
ambient temperatures to +65°C with 100 lfm
air flow.
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.
+INPUT
(2)
+OUTPUT
(4)
+SENSE
(6)
COMMON
(3)
CURRENT
SENSE
V
CC
ON/OFF
CONTROL
(1)
PWM
CONTROLLER
REFERENCE &
ERROR AMP
V
OUT
TRIM
(5)
COMMON
(3)
Typical topology is shown
Figure 1. Simplified Schematic
For full details go to
www.murata-ps.com/rohs
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MDC_LSM 16A D12 Models.A05 Page 1 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Performance Specifications and Ordering Guide
➀
ORDERING GUIDE
Output
V
OUT
(Volts)
0.75
1
1.2
1.5
1.8
2
2.5
3.3
5
0.75-5
Input
Regulation (Max.)
➂
Line
±0.1%
±0.1%
±0.1%
±0.1%
±0.1%
±0.1%
±0.1%
±0.1%
±0.1%
±0.1%
Efficiency (Full Load)
I
IN
➃
(mA/A)
35/1.26
35/1.57
40/1.84
50/2.26
55/2.67
55/2.93
60/3.62
70/4.68
85/7.06
85/7.02
Models
LSM-0.75/16-D12
LSM-1/16-D12
LSM-1.2/16-D12
LSM-1.5/16-D12
LSM-1.8/16-D12
LSM-2/16-D12
LSM-2.5/16-D12
LSM-3.3/16-D12
LSM-5/16-D12
LSM-T/16-D12
I
OUT
(Amps)
16
16
16
16
16
16
16
16
16
16
R/N (mVp-p)
➁
Typ.
50
50
50
50
50
50
50
50
75
50
Max.
75
75
75
75
75
75
75
75
100
75
Load
±0.375%
±0.25%
±0.25%
±0.25%
±0.25%
±0.25%
±0.25%
±0.25%
±0.25%
±0.25%
V
IN
Nom.
(Volts)
12
12
12
12
12
12
12
12
12
12
Range
(Volts)
10-14
10-14
10-14
10-14
10-14
10-14
10-14
10-14
10-14
10-14
V
IN
= nom.
Min.
83%
83%
85%
86.5%
88%
89%
90%
92%
92.5%
93%
V
IN
= min
Typ.
86%
86%
88%
89.5%
91%
91.5%
91.5%
94.5%
95.5%
95.5%
Typ.
85%
85%
87%
88.5%
90%
91%
92%
94%
94.5%
95%
Package
(Case,
Pinout)
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
➀
Typical at T
A
= +25°C under nominal line voltage and full-load conditions, 200 lfm air flow for
extended operation, unless otherwise noted. All models are tested and specified with external
22µF tantalum input and output capacitors. These capacitors are necessary to accommodate our
test equipment and may not be required to achieve specified performance in your applications.
See I/O Filtering and Noise Reduction.
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.
Part Number Structure
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
RoHS6 compliance does not claim EU RoHS exemption 7b–lead in solder.
Mechanical Specifications
1.30
(33.02)
L SM
-
1.8
/
16
-
D12
-
C
Output
Configuration:
L
= Unipolar
Low Voltage
Non-Isolated SMT
Nominal Output Voltage:
0.75, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3 or 5 Volts
Note: Not all model number combinations
are available. Contact MPS.
1.36
(34.54)
Dimensions are in inches (mm shown for ref. only).
Third Angle Projection
RoHS6 hazardous substance
compliant*➄
Input Voltage Range:
D12
= 10 to 14 Volts
(12V nominal)
Maximum Rated Output
Current in Amps
* Contact Murata Power Solutions for
availability.
0.34
(8.64)
SMT COPPER LEADS
COPLANAR 0.004
0.570 (14.48)
3 EQ. SP. @
0.190 (4.83)
0.085
(2.16)
Tolerances (unless otherwise specified):
.XX ± 0.02 (0.5)
.XXX ± 0.010 (0.25)
Angles ± 2˚
Components are shown for reference only.
0.310
(7.87)
Case C45
3
0.55
(13.97)
4
5
6
1
0.062
(1.57)
TYP.
2
0.53
0.48
(12.19) (13.46)
0.010
(0.254)
0.570 (14.48)
3 E Q . S P. @
0.190 (4.83)
0.60
(15.24)
0.112
(2.84)
TYP.
NOTCH IN SHELL
INDICATES PIN ONE
0.05
(1.27)
BOTTOM VIEW
0.075
(1.91)
0.048
(1.22)
0.310
(7.87)
0.375
(9.53)
0.052
(1.32)
1.177
(29.90)
0.570 (14.48)
3 EQ. SP. @
0.190 (4.83)
3
2
4
5
6
1
0.297
(7.54)
0.310
(7.87)
0.062
(1.57)
0.112 T Y P.
(2.84)
0.049
(1.24)
0.047
(1.19)
0.052
(1.32)
CAUTION
PRESS TO REMOVE
THE HEAT SHIELD
AFTER THE SOLDER
PROCESS
NOTCH IN SHELL
INDICATES PIN ONE
0.405
(10.29)
1
6
5
4
3
2
0.430
(10.92)
BOTTOM VIEW
LSM WITH REMOVABLE HEAT SHIELD
FOR HIGH TEMPERATURE SOLDER
RECOMMENDED PAD LAYOUT
Recommended Pad Size: 0.15 x 0.10 (3.81 x 2.54)
I/O Connections
Pin
Function P63
1
On/Off Control
2
+Input
3
Common
4
+Output
5
V
OUT
Trim
6
+Sense
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MDC_LSM 16A D12 Models.A05 Page 2 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Performance/Functional Specifications
Input
Typical @ T
A
= +25°C under nominal line voltage and full-load conditions unless noted.
➀
➀
All models are tested and specified with external 22µF tantalum input and output capacitors.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
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 filtering. See
I/O Filtering and Noise Reduction.
➄
MTBF’s are calculated using Telcordia SR-332(Bellcore), ground fixed, T
a
= +25°C, full power,
natural convection, +67°C pcb temperature.
➅
Input Ripple Current is tested/specified 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 Range
Startup Voltage
10-14 Volts (12V nominal)
8.5-9.2 Volts (model dependent)
Input Current:
Normal Operating Conditions
See Ordering Guide
Inrush Transient
0.08A
2
sec
Standby/Off Mode
1.5mA
Output Short-Circuit Condition
➁
12-40mA average (model dependent)
Input Reflected 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
Absolute Maximum Ratings
Input Voltage:
Continuous or transient
On/Off Control
(Pin 1)
Input Reverse-Polarity Protection
Output Overvoltage Protection
Output Current
15 Volts
+6V
None
None
Current limited. Devices can
withstand sustained output short
circuits without damage.
–55 to +125°C
See Reflow Solder Profile
V
OUT
Accuracy
(50% load)
Minimum Loading
➀
Maximum Capacitive Load
V
OUT
Trim Range
Ripple/Noise
(20MHz BW)
➀ ➁ ➃
±1.25%
No load
1000µF (low ESR, OSCON)
±10%
See Ordering Guide
Total Accuracy
3% over line/load/temperature
Efficiency
See Ordering Guide
Overcurrent Detection and Short-Circuit Protection:
➁
Current-Limiting Detection Point
21-33 Amps (model dependent)
Short-Circuit Detection Point
98% of V
OUT
set
SC Protection Technique
Hiccup with auto recovery
Short-Circuit Current
125-420mA average (model dependent)
Dynamic Characteristics
Storage Temperature
Lead Temperature
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 Specifications Table is not implied.
Technical Notes
Transient Response
(50% load step)
Start-Up Time:
➁
V
IN
to V
OUT
and On/Off to V
OUT
Switching Frequency
Calculated MTBF
➄
LSM-1.2/16-D12
LSM-1.5/16-D12
LSM-1.8/16-D12
LSM-2.5/16-D12
LSM-3.3/16-D12
LSM-5/16-D12
Operating Temperature:
(Ambient)
➁
Thermal Shutdown
30-135µsec to ±2% of final value
(model dependent)
60msec for V
OUT
= 1V and 0.75V
40msec for V
OUT
= 1.2V to 5V
260kHz ±10%
Environmental
I/O Filtering and Noise Reduction
All models in the LSM D12 Series are tested and specified 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 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 22μF 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 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 specific system configuration
may necessitate additional considerations.
9,160,138 hours
8,674,318 hours
8,334,117 hours
8,534,580 hours
7,817,255 hours
7,756,061 hours
–40 to +85°C (with Derating)
See Derating Curves
+115°C (110 to 125°C)
Physical
Dimensions
Lead Dimensions/Material
Weight
Flamability Rating
Safety
1.3" x 0.53" x 0.34" (33.03 x 13.46 x 8.64)
0.112" x 0.062" (2.84 x 1.57mm) rectangular
copper alloy with gold plate over nickel
underplate
0.28 ounces (7.8g)
UL94V-0
Designed to meetUL/cUL/IEC/EN 60950-1,
CSA-C22.2 No. 234
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MDC_LSM 16A D12 Models.A05 Page 3 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
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 specifications
(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.
Figure 2. Measuring Input Ripple Current
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 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.
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 specified
absolute maximum ratings and input polarity reversals of longer than "instan-
taneous" duration can cause permanent damage to these devices.
Start-Up Time
The V
IN
to V
OUT
Start-Up Time is the interval between the time at which a ramp-
ing input voltage crosses the lower limit of the specified input voltage range
(10 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.
The On/Off to V
OUT
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 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 V
OUT
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 V
OUT
.
[V
OUT
(+) – Common] – [Sense(+) – Common]
≤
10%V
OUT
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 specified rating. Therefore:
(V
OUT
at pins) x (I
OUT
)
≤
rated output power
+SENSE
+OUTPUT
6
4
COPPER STRIP
C1
C2
SCOPE
R
LOAD
COMMON
3
COPPER STRIP
C1
=
NA
C2
=
22µF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE
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
filtering to meet your specific 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 efficiency.
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MDC_LSM 16A D12 Models.A05 Page 4 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
The internal 10.5Ω 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 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 V
IN
(+Input).
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 (V
OUT
= V
IN
). 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 fixed resistor. The
trimpot should be connected between +Output and Common with its wiper
connected to the Trim pin as shown in Figure 6 below.
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 6. Trim Connections Using a Trimpot
A trimpot can be used to determine the value of a single fixed 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.
Figure 5. Driving The External Power-Up Open Collector
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MDC_LSM 16A D12 Models.A05 Page 5 of 12
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