www.murata-ps.com
LSM2 Series
Single Output, Non-Isolated
Selectable-Output POL DC/DC Converters
Typical Unit
Murata Power Solutions’ miniature POL switching DC/DC
converters are ideal regulation and supply elements for
mixed voltage systems.
FEATURES
Point-of-load (POL) converters for
mixed voltage systems
& 12V wide input ranges
5V
10 or 16 Amp maximum outputs
6,
DOSA compatible SMT package
Meets RoHS-6 compliance
Phased start up sequencing and tracking
Extensive self-protection
Starts up into pre-biased loads
PRODUCT OVERVIEW
They are fully compatible with the Distributed-
power Open Standards Alliance specification
(www.dosapower.com). LSM2s can power CPU’s,
programmable logic and mixed voltage systems
with little heat and low noise. A typical applica-
tion uses a master isolated 12 or 5 Volt DC supply
and individual LSM2 converters for local 1.8 and
3.3 Volt DC supplies. All system isolation resides
in the central supply, leaving lower cost POL
regulation right at the load. Unlike linear regula-
tors, the LSM2’s can deliver very high power (up to
52 Watts) in a tiny area with no heat sinking and no
external components needed. They feature quick
transient response (to 25µsec) and very fast current
slew rates (to 20A/µsec).
CONNECTION DIAGRAM
+INPUT
+OUTPUT
+SENSE
COMMON
V
CC
ON/OFF
CONTROL
V
TRACK
/
SEQUENCE
INPUT
PWM
CONTROLLER
CURRENT
SENSE
POWER
GOOD
COMMON
REFERENCE &
ERROR AMP
VOUT
TRIM
Typical topology is shown
For full details go to
www.murata-ps.com/rohs
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MDC_LSM2 Series.D02∆
Page 1 of 17
LSM2 Series
Single Output, Non-Isolated
Selectable-Output POL DC/DC Converters
PERFORMANCE SPECIFICATIONS AND ORDERING GUIDE
Output
Root Model
LSM2-T/6-W3-C
LSM2-T/6-D12-C
LSM2-T/10-W3-C
LSM2-T/10-D12-C
LSM2-T/16-W3-C
Input
Regulation
Line
±0.11%
±0.075%
±0.15%
±0.07%
±0.1%
±0.1%
V
OUT
(Volts)
0.75-3.3
0.75-5
0.75-3.3
0.75-5
0.75-3.3
I
OUT
(Amps)
6
6
10
10
16
16
Power
(Watts)
19.8
30.0
33.0
50.0
52.8
80.0
R/N (mVp-p)
Typ.
20
30
58
62
83
90
Max.
40
90
79
80
110
125
Load
±0.075%
±0.15%
±0.075%
±0.15%
±0.075%
±0.21%
V
IN
Nom. Range
I
IN
(Volts) (Volts) (mA/A)
5
12
5
12
5
12
2.4-5.5
8.3-13.2
2.4-5.5
2.4-5.5
8.3-13.2
50/4.15
70/2.68
75/6.91
70/11.15
100/7.1
Efficiency
Min.
93%
91.9%
94%
92.8%
93%
Typ.
95.5%
93.4%
95.5%
95.4%
94.7%
94%
Package
(Case/Pinout)
C63, P67
C63, P67
C62, P66
C62, P66
C62, P66
C62, P66
8.3-13.2 100/4.368 93.5%
LSM2-T/16-D12-C
0.75-5
Typical at T
A
= +25°C under nominal line voltage and full-load conditions, unless noted.
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.
These devices have no minimum-load requirements and will regulate under no-load
Nominal line voltage, no-load/full-load conditions.
LSM2-T16-D12 efficiencies are shown at 5V
OUT
.
V
IN
must be
≥0.5V
greater than V
OUT
.
These are not complete model numbers. Please refer to the Part Number Structure
conditions. Regulation specifications describe the output-voltage deviation as the line
voltage or load is varied from its nominal/midpoint value to either extreme.
when ordering.
➇
RoHS-6 compliance does not claim EU RoHS exemption 7b (lead in solder).
PART NUMBER STRUCTURE
L SM2
-
T
/
16
-
D12 N G
-
C
Output Configuration:
L
= Unipolar
Low Voltage
RoHS6 compliant*
(see note 8)
Power Good Output: **
Blank
= Omitted
G
= Installed
On/Off Polarity:
Blank
= Positive polarity
N
= Negative polarity
Input Voltage Range:
D12
= 8.3-14 Volts (12V nominal)
W3
= 2.4-5.5 Volts (5V nominal)
Note:
Not all model number combinations
are available. Contact MPS.
* Contact MPS (DATEL) for availability.
Non-Isolated SMT
Nominal Output Voltage:
0.75-3.3 Volts (W3)
0.75-5 Volts (D12)
Maximum Rated Output
Current in Amps
** The Power Good option is not available for
LSM2-T/10-D12 and LSM2-T/16-D12. Models
without Power Good do not install pad 8 (10/16
Amp). For 6 Amp models, pad 7 is only installed
for “G” models.
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MDC_LSM2 Series.D02∆
Page 2 of 17
LSM2 Series
Single Output, Non-Isolated
Selectable-Output POL DC/DC Converters
Performance/Functional Specifications
(1)
INPUT
Pre-bias Startup
(15)
Sequencing
Slew Rate
Startup delay until sequence start
Tracking accuracy, rising input
Tracking accuracy, falling input
Sequence pin input impedance
Remote Sense to V
OUT
Power Good Output
(17)
(“G” suffix)
Power_Good Configuration
Input Voltage Range
Isolation
Start-Up Threshold
W3 Models
12V Models
Undervoltage Shutdown
W3 Models
12V Models
Overvoltage Shutdown
Reflected (Back) Ripple Current
(2)
Internal Input Filter Type
Reverse Polarity Protection
Input Current:
Full Load Conditions
Inrush Transient
Shutdown Mode (Off, UV, OT)
Output Short Circuit
Low Line (V
IN
= V
MIN
)
LSM2-T/6-W3
LSM2-T/6-D12
LSM2-T/10-W3
LSM2-T/10-D12
LSM2-T/16-W3
LSM2-T/16-D12
Remote On/Off Control:
(5)
Positive Logic (no model suffix)
Negative Logic (“N” model suffix)
Current
Voltage Output Range
Minimum Loading
Accuracy
(50% load)
Voltage Adjustment Range
(13)
Temperature Coefficient
Ripple/Noise
(20 MHz bandwidth)
Efficiency
Maximum Capacitive Loading:
LSM2-T/6 models:
Cap-ESR = 0.001 to 0.01W
Cap-ESR >0.01W
LSM2-T/10 and -T/16 models:
Cap-ESR = 0.001 to 0.01W
Cap-ESR >0.01W
(14)
See Ordering Guide
Not isolated, input and output use the same
common return.
2.2 Volts
8 Volts
2.0 Volts
7.5 Volts
None
20-70mAp-p (model dependent)
Capacitive
See fuse information
See Ordering Guide
0.1-0.4A
2
sec (model dependent)
5mA
60mA
5.54 Amps
3.79 Amps
9.14 Amps
6.375 Amps
14.63 Amps
10.2 Amps
OFF = ground pin to +0.3V max.
ON = open pin or +V
IN
max.
ON = Open pin or 0 to +0.3V max.
OFF = +2.5V to +V
IN
max.
1mA max.
OUTPUT
Converter will start up if the external
output voltage is less than V
NOM
2V max. per millisecond
10 milliseconds
V
OUT
= ±100mV of Sequence In
V
OUT
= ±200mV of Sequence In
400kW to 1MW
0.5V max.
(7)
TRUE (OK) = open drain
FALSE (not OK) = Signal Ground to 0.4V
MOSFET to ground with external user
pullup, 10mA max. sink
DYNAMIC CHARACTERISTICS
Dynamic Load Response
25µsec to ±2% of final value
(50-100-50% load step, di/dt = 20A/µsec)
Start-Up Time
7msec for V
OUT
= nominal
(V
IN
on to V
OUT
regulated or On/Off to V
OUT
)
Switching Frequency
LSM2-T/6 models
LSM2-T/10 and -T/16 models
Calculated MTBF
(4)
315kHz
230kHz
ENVIRONMENTAL
TBC Hours
Operating Temperature Range
(Ambient) –40 to +85°C with derating
(9)
See Derating Curves
Operating PC Board TemUperature
Storage Temperature Range
Thermal Protection/Shutdown
Relative Humidity
Outline Dimensions
Removable Heat Shield
Weight
Lead Material
Electromagnetic Interference
EN55022
(conducted and radiated)
Safety
C22.2
60950-1
Flammability
–40 to +100°C max.
(12)
–55 to +125°C
+115°C
to 85% / +85°C, non-condensing
PHYSICAL
See Mechanical Specifications
Nylon 46
0.28 ounces (7.8 grams)
Tin-plated copper alloy
Designed to meet FCC part 15, class B,
(may need external filter)
Designed to meet UL/cUL 60950-1 CSA-
No.234 IEC/EN
UL94V-0
ABSOLUTE MAXIMUM RATINGS
See Ordering Guide
No minimum load
±2% of V
NOM
See Ordering Guide
±0.02% of V
OUT
range per °C
See Ordering Guide and
(8)
See Ordering Guide
Line/Load Regulation
(See Tech Notes) See Ordering Guide and
(10)
3000µF
5000µF
5000µF
10,000µF
10 Amps (after warm up)
16.75 Amps (after warm startup)
21–31 Amps (after warm up)
600mA
Hiccup autorecovery on overload removal
Continuous, no damage (output shorted to
Input Voltage
(Continuous or transient)
W3 models
12V models
On/Off Control
Input Reverse Polarity Protection
Output Current
(7)
+7 Volts
+15 Volts
–0.3V min. to +V
IN
max.
See Fuse section
Current-limited. Devices can
withstand sustained short circuit
without damage.
–55 to +125°C
Current Limit Inception:
(98% of V
OUT
)
LSM2-T/6 models
LSM2-T/10 models
LSM2-T/16 models
Short Circuit Mode
(6)
Short Circuit Current Output
Protection Method
(16)
Short Circuit Duration
ground)
Storage Temperature
Lead Temperature
(soldering 10 sec. max.) +280°C
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.
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MDC_LSM2 Series.D02∆
Page 3 of 17
LSM2 Series
Single Output, Non-Isolated
Selectable-Output POL DC/DC Converters
Performance/Functional Specification Notes:
(1)
All models are tested and specified with external 1 || 10µF ceramic/tantalum output
capacitors and a 22µF external input capacitor. All capacitors are low ESR types. These
capacitors are necessary to accommodate our test equipment and may not be required
to achieve specified performance in your applications. All models are stable and
regulate within spec under no-load conditions.
General conditions for Specifications are +25°C, V
in
= nominal, V
out
= nominal, full
load. “Nominal” output voltage is +5V for D12 models and +3.3V for W3 models.
Input Back Ripple Current is tested and specified over a 5-20MHz bandwidth. Input
filtering is C
in
= 2 × 100µF tantalum, C
bus
= 1000µF electrolytic, L
bus
= 1µH.
Note that Maximum Power Derating curves indicate an average current at nominal
input voltage. At higher temperatures and/or lower airflow, the DC/DC converter will
tolerate brief full current outputs if the total RMS current over time does not exceed the
derating curve.
Mean Time Before Failure is calculated using the Telcordia (Belcore) SR-332 Method 1,
Case 3, ground fixed conditions, T
pcboard
= +25°C, full output load, natural air convec-
tion.
The On/Off Control may be driven with external logic or by applying appropriate exter-
nal voltages which are referenced to –Input Common. The On/Off Control Input should
use either an open collector/open drain transistor or logic gate which does not exceed
+V
in
. A 68KΩ external pullup resistor to +V
in
will cause the “ON” state for negative
logic models.
Short circuit shutdown begins when the output voltage degrades approximately 2%
from the selected setting.
TECHNICAL NOTES
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(2)
(3)
(4)
(5)
(6)
If Sense is connected remotely at the load, up to 0.5 Volts difference is allowed
between the Sense and +V
out
pins to compensate for ohmic voltage drop in the power
lines. A larger voltage drop may cause the converter to exceed maximum power dis-
sipation. Connect sense to +V
out
if not used.
Output noise may be further reduced by adding an external filter. See I/O Filtering and
Noise Reduction.
All models are fully operational and meet published specifications, including “cold
start” at –40°C.
Regulation specifications describe the deviation as the line input voltage or output load
current is varied from a nominal midpoint value to either extreme.
Other input or output voltage ranges are available under scheduled quantity special order.
Maximum PC board temperature is measured with the sensor in the center.
Do not exceed maximum power specifications when adjusting the output trim.
The maximum output capacitive loads depend on the the Equivalent Series Resistance
(ESR) of the external output capacitor.
Do not use Pre-bias startup and sequencing together. See Technical Notes below.
After short circuit shutdown, if the load is partially removed such that the load still ex-
ceeds the overcurrent (OC) detection, the converter will remain in hiccup restart mode.
When Sequencing is not used, the Power Good output is TRUE at any time the output
is within approximately ±10% of the voltage set point. Power Good basically indicates
if the converter is in regulation. Power Good detects Over Temperature if the PWM has
shut down due to OT. Power Good does not directly detect Over Current.
If Sequencing is in progress, Power Good will falsely indicate TRUE (valid) before the
output reaches its setpoint. Ignore Power Good if Sequencing is in transition.
I/O Filtering and Noise Reduction
All models in the LSM2 Series are tested and specified with external 1 || 10µF
ceramic/tantalum output capacitors and a 22µF tantalum input capacitor. These
capacitors are necessary to accommodate our test equipment and may not be
required to achieve desired performance in your application. The LSM2s are
designed with high-quality, high-performance internal I/O caps, and will oper-
ate within spec in most applications with no additional external components.
In particular, the LSM2’s input capacitors are specified for low ESR and
are fully rated to handle the units' input ripple currents. Similarly, the internal
output capacitors are specified for low ESR and full-range frequency response.
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 impedances
can greatly affect system stability. Your specific system configuration may
necessitate additional considerations.
Output ripple/noise (also referred to as periodic and random deviations or
PARD) may be reduced below specified limits with the installation of additional
external output capacitors. Output capacitors function as true filter elements
and should be selected for bulk capacitance, low ESR, and appropriate 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 function
of your line voltage and source impedance, as well as your particular load and
layout conditions.
Input Fusing
Most applications and or safety agencies require the installation of fuses at the
inputs of power conversion components. The LSM2 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.
Safety Considerations
LSM2 SMTs are non-isolated DC/DC converters. In general, all DC/DCs must
be installed, including considerations for I/O voltages and spacing/separation
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.
Input Overvoltage and Reverse-Polarity Protection
LSM2 SMT Series DC/DCs 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 "instantaneous"
duration can cause permanent damage to these devices.
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MDC_LSM2 Series.D02∆
Page 4 of 17
LSM2 Series
Single Output, Non-Isolated
Selectable-Output POL DC/DC Converters
TO
OSCILLOSCOPE
CURRENT
PROBE
L
BUS
C
BUS
–
3
C
IN
= 2 x 100µF, ESR < 700mΩ @ 100kHz
C
BUS
= 1000µF, ESR < 100mΩ @ 100kHz
L
BUS
= 1µH
COMMON
C
IN
2
+INPUT
+
V
IN
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 LSM2's specified rating. Therefore:
(V
OUT
at pins) x (I
OUT
)
≤
rated output power
The internal 10.5W 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 must
be tied to +Output at the DC/DC converter pins.
Sense Input
Use the Sense input with caution. Many applications do not need the Sense
connection. Sense is intended to correct small output accuracy errors caused
by the resistive ohmic drop in output wiring as output current increases. This
output drop (the difference between Sense and V
OUT
when measured at the
converter) should not be allowed to exceed 0.5V. Consider using heavier wire if
this drop is excessive.
Sense is connected at the load and corrects for resistive errors only. Be
careful where it is connected. Any long, distributed wiring and/or significant
inductance introduced into the Sense control loop can adversely affect overall
system stability. If in doubt, test the application, and observe the DC/DC's output
transient response during step loads. There should be no appreciable ringing or
oscillation. You may also adjust the output trim slightly to compensate for voltage
loss in any external filter elements. Do not exceed maximum power ratings.
On/Off Control
The On/Off Control pin may be used for remote on/off operation. LSM2 Series
DC/DC converters are designed so that they are enabled when the control pin
is left open (open collector).
Dynamic control of the on/off function is best accomplished with a me-
chanical 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.
Figure 2. Measuring Input Ripple Current
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
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 volt-
age as it appears to the converter.
+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 Output Ripple/Noise (PARD)
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
LSM2 Series offer an output sense function. 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.
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MDC_LSM2 Series.D02∆
Page 5 of 17
Analogue and Mixed Signal
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