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Figure 1. Simplifi ed Schematic
LSN Series W3 are ideal building blocks for emerg-
ing, on-board power-distribution schemes in which
isolated 3 to 5.5V buses deliver power to any num-
ber of non-isolated, step-down buck regulators.
LSN W3 DC/DC’s accept 3 to 5.5 Volts 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, or 3.3 Volt output
fully rated at 16 Amps.
LSN W3’s are ideal point-of-use/load power
processors. They typically require no external com-
ponents. 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 LSN’s best-in-class power density
is achieved with a fully synchronous, fixed-
frequency, buck topology that also delivers:
high efficiency (97%, 3.3Vout, 8A), low noise
(30mVp-p typ.), tight line/load regulation
(±0.1%/±0.25% max.), quick step response
(30μsec), stable no-load operation, and no
output reverse conduction.
The fully functional LSN’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 en-
ables the LSN W3’s to deliver rated output currents
of 16 Amps at ambient temperatures to +65°C
with natural convection.
If your new system boards call for multiple sup-
ply voltages, check out the economics of on-board
3-5.5V distributed power. If you don’t need to pay
for multiple isolation barriers, DATEL’s non-isolated
LSN W3 SMT’s will save you money.
Typical unit
FEATURES
Step-down, wide input buck regulators
for distributed 3-5V power architectures
3V to 5.5V wide-input range
0.75/1/1.2/1.5/1.8/2/2.5/3.3VOUT @16A
Non-isolated, fi xed-frequency,
synchronous-rectifi er topology
±1% setpoint accuracy
Effi ciencies to 95% @ 16 Amps
Noise as low as 30mVp-p
Stable no-load operation
Remote on/off control
Sense pin and output voltage trim
No derating to +65°C with no fan
UL/IEC/EN60950-1 certifi cation pending
EMC compliant
PRODUCT OVERVIEW
Typical topology is shown.
Single Output LSN-W3 Models
Non-Isolated, 3-5.5VIN, 0.75-3.3VOUT
16 Amp DC/DC Converters
For full details go to
www.murata-ps.com/rohs
www.murata-ps.com
www.murata-ps.com
email: sales@murata-ps.com
10 Dec 2009 MDC_LSN W3 Models.A02 Page 1 of 8
NOT RECOMMENDED
FOR NEW DESIGNS
Output
Confi guration:
L = Unipolar
Low Voltage
PART NUMBER STRUCTURE
Maximum Rated Output
Current in Amps
Non-Isolated SIP
Nominal Output Voltage:
0.75, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3
or 0.75-3.3 Volts
Input Voltage Range:
W3 = 3-5.5 Volts
(5V nominal)
L SN -/W3-1.8 H
Blank = Vertical Mount
H = Horizontal Mount
J = Reversed Pin
Vertical Mount
16
Note: Not all model number
combinations are available.
Contact MPS.
C
-
RoHS-6 compliant*
* Contact MPS for availability.
➀ Typical at TA = +25°C under nominal line voltage and full-load conditions, unless noted. All models
are tested/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 V
IN = 4.5 Volts minimum for VOUT = 3.3 Volts.
➅ Unless noted, LSN-T/16-W3 specifi cations are at 3.3VOUT.
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Pin Function P59 Pin Function P59 Pin Function P59
1 +Output 5 Common 9 No Pin
2 +Output 6 Common 10 VOUT Tr i m
3 +Sense 7 +Input 11 On/Off Control
4 +Output 8 +Input
I/O Connections
Dimensions in inches (mm)
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.
LSN-0.75/16-W3 0.75 16 30 50 ±0.1% ±0.25% 5 3-5.5 70/2.79 84% 86% 86.5% B8/B8x, P59
LSN-1/16-W3 1 16 30 50 ±0.1% ±0.25% 5 3-5.5 70/3.72 84% 86% 86.5% B8/B8x, P59
LSN-1.2/16-W3 1.2 16 30 50 ±0.1% ±0.25% 5 3-5.5 70/4.36 86% 88% 88.5% B8/B8x, P59
LSN-1.5/16-W3 1.5 16 30 50 ±0.1% ±0.25% 5 3-5.5 70/5.33 88% 90% 90.5% B8/B8x, P59
LSN-1.8/16-W3 1.8 16 30 50 ±0.1% ±0.25% 5 3-5.5 70/6.30 89.5% 91.5% 92% B8/B8x, P59
LSN-2/16-W3 2 16 30 50 ±0.1% ±0.25% 5 3-5.5 70/6.92 90.5% 92.5% 92.5% B8/B8x, P59
LSN-2.5/16-W3 2.5 16 30 50 ±0.1% ±0.25% 5 3-5.5 70/8.56 91.5% 93.5% 94% B8/B8x, P59
LSN-3.3/16-W3 3.3 16 30 50 ±0.1% ±0.25% 5 3-5.5➄50/11.12 93% 95% 95% B8/B8x, P59
LSN-T/16-W3 0.75-3.3 16 30 50 ±0.05% ±0.15% 5 3-5.5➄50/11.12 93% 95% 95% B8/B8x, P59
Performance Specifi cations and Ordering Guide ➀
Preliminary
PART NUMBER STRUCTURE MECHANICAL SPECIFICATIONS
Component locations are
typical and may vary.
Standard product pin lengths are shown.
Single Output LSN-W3 Models
Non-Isolated, 3-5.5VIN, 0.75-3.3VOUT
16 Amp DC/DC Converters
www.murata-ps.com email: sales@murata-ps.com
10 Dec 2009 MDC_LSN W3 Models.A02 Page 2 of 8
Input
Input Voltage Range 3-5.5 Volts (5V nominal) ➇
Input Current:
Normal Operating Conditions See Ordering Guide
Inrush Transient 0.02A2 sec
Standby/Off Mode 8mA
Output Short-Circuit Condition ➁ 60-110mA average (model dependent)
Input Refl ected Ripple Current ➁ ➅ 10-20mAp-p, model dependent
Input Filter Type Capacitive
Overvoltage Protection None
Reverse-Polarity Protection None. Install external fuse.
Undervoltage Shutdown None
On/Off Control ➁ ➂ On = open or low (<0.4V max.)
Off = high (>2.5V to VIN max.), 1mA
Output
VOUT Accuracy (50% load) ±1.5% ➆
Temperature Coeffi cient ±0.02%/°C
Minimum Loading ➀ No load
Maximum Capacitive Load 5000μF (electrolytic),
2000μF (0.02: 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 20-36 Amps (model dependent)
Short-Circuit Detection Point 98% of VOUT set
SC Protection Technique Hiccup with auto recovery
Short-Circuit Current 600mA average
Dynamic Characteristics
Transient Response (50% load step) 30-70μsec to ±2% of fi nal value
(model dependent)
Start-Up Time: ➁
VIN to VOUT and On/Off to VOUT 7msec
Switching Frequency 300 ±50kHz
Environmental
Calculated MTBF ➄ TBD
Operating Temperature: (Ambient) ➁
Without Derating (Natural convection) –40 to +63/71°C (model dependent,
see Derating Curves)
With Derating See Derating Curves
PC-Board Temperature +100°C maximum
Thermal Shutdown +115°C (110 to 125°C)
Physical
Dimensions See Mechanical Specifi cations
Pin Dimensions/Material 0.112" x 0.062" (2.84 x 1.57mm) rectangular
tellurium copper alloy with 100-300
microinches of tin electroplate over
100 microinches of nickel underplate
Weight 0.28 ounces (7.8g)
Flamability Rating UL94V-0
EMI EN55022/CISPR22 (requires external fi lter)
Safety UL/cUL/IEC/EN 60950-1, CSA-C22.2 No.234
➀ All models are tested/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.
Performance/Functional Specifi cations
Typical @ TA = +25°C under nominal line voltage and full-load conditions unless noted. ➀
Input Voltage:
Continuous or transient 6 Volts (0.75, 1, 1.2, 1.5, 1.8, 2, 2.5 VOUT)
7 Volts (3.3VOUT and "T" models)
On/Off Control (Pin 1) +VIN
Input Reverse-Polarity Protection None. Install external fuse.
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 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
TECHNICAL NOTES
I/O Filtering and Noise Reduction
All models in the LSN W3 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 LSN’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 LSN’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.
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.
➂ The On/Off Control 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.
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, T
A = +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 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.
➆ Setting accuracy for LSN-T/16-W3 is ±2%.
➇ Input voltage must be 4.5V minimum for 3.3V output.
Single Output LSN-W3 Models
Non-Isolated, 3-5.5VIN, 0.75-3.3VOUT
16 Amp DC/DC Converters
www.murata-ps.com email: sales@murata-ps.com
10 Dec 2009 MDC_LSN W3 Models.A02 Page 3 of 8
Input Fusing
Most applications and or safety agencies require the installation of fuses at the
inputs of power conversion components. The LSN W3 Series are not inter-
nally 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
fast-blow fuse with a typical value of about twice the maximum input current,
calculated at low line with the converter’s minimum effi ciency.
Safety Considerations
LSN W3 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/separation
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
LSN W3 SMT Series DC/DC’s do not incorporate either input overvoltage
or input reverse-polarity protection. Input voltages in excess of the speci-
fi ed absolute maximum ratings and input polarity reversals of longer than
“instantaneous” 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
LSN
W3
SMT Series DC/DC converters offer an output sense function on pin 3.
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.
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
C1
C1 = NA
C2 = 22μF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE
C2 R
LOAD
COPPER STRIP
COPPER STRIP
SCOPE
+OUTPUT
COMMON
+SENSE
Figure 3. Measuring Output Ripple/Noise (PARD)
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.
You should add only enough output capacitance to attenuate the noise to
your desired level. Large amounts of output capacitance cause poor dynamic
response (step load changes, etc.). Too great an output capacitor can make the
converter oscillate (actually increasing the noise!) while substantial capaci-
tance which is less than the oscillation threshold can still cause ringing and
overshoot. Finally, you must use less output capacitance if the cap is a low
ESR type (OSCON, etc.).
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.
C
IN
V
IN
C
BUS
L
BUS
C
IN
= 2 x 100μF, ESR < 700m7 @ 100kHz
C
BUS
= 1000μF, ESR < 100m7 @ 100kHz
L
BUS
= 1μH
+INPUT
COMMON
CURRENT
PROBE
TO
OSCILLOSCOPE
+
–
Single Output LSN-W3 Models
Non-Isolated, 3-5.5VIN, 0.75-3.3VOUT
16 Amp DC/DC Converters
www.murata-ps.com email: sales@murata-ps.com
10 Dec 2009 MDC_LSN W3 Models.A02 Page 4 of 8
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] d 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 LSN’s specifi ed rating. Therefore:
(VOUT at pins) x (IOUT) d rated output power
The internal 10.5: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 3) must be tied to +Output (pin 4) at the DC/DC converter pins.
On/Off Control and Power-up Sequencing
The On/Off Control pin may be used for remote on/off operation. LSN W3 SIP
Series DC/DC’s are designed so they are enabled when the control pin is left
open (internal pull-down to Common) and disabled when the control pin is
pulled high (+2.5V to +VIN), as shown in Figures 4 and 5.
Dynamic control of the on/off function is best accomplished with a mechani-
cal relay or open-collector/open-drain drive circuit. The drive circuit should
be able to sink appropriate current when activated and withstand appropriate
voltage when deactivated.
Figure 4. Driving the On/Off Control Pin with an Open-Collector Drive Circuit
The on/off control function, however, can be externally inverted so that
the converter will be disabled while the input voltage is ramping up and then
“released” once the input has stabilized.
For a controlled start-up of one or more LSN-W3’s, or if several output volt-
ages need to be powered-up in a given sequence, the On/Off Control pin can be
pulled high (external pull-up resistor, converter disabled) and then driven low
with an external open collector device to enable the converter.
Output Overvoltage Protection
LSN W3 Series DC/DC converters do not incorporate output overvoltage protec-
tion. 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. LSN W3 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 50% (24 Amps)
or if the output voltage drops to less than 98% of it original value, the LSN W3’s
internal overcurrent-detection circuitry immediately turns off the converter,
which then goes into a "hiccup" mode. While hiccupping, the converter will
continuously attempt to restart itself, go into overcurrent, and then shut down.
Under these conditions, 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 LSN W3 Series are ±10%. Trim-
ming 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
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Single Output LSN-W3 Models
Non-Isolated, 3-5.5VIN, 0.75-3.3VOUT
16 Amp DC/DC Converters
www.murata-ps.com email: sales@murata-ps.com
10 Dec 2009 MDC_LSN W3 Models.A02 Page 5 of 8
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).
“T” Model (LSN-T/16-W3)
This version of the the LSN-W3 series offers a special output voltage trim-
ming feature which is fully compatible with competitive units. The output
voltage may be varied using a single trim resistor from the Trim Input to Power
Common. The output voltage range is 0.75 Volts to 3.3 Volts.
IMPORTANT: For outputs greater than 3 Volts up to 3.3 Volts maximum, the
input supply must be 4.5 Volts minimum.
As with other trim adjustments, be sure to use a precision low-tempco
resistor (±100 ppm/°C) mounted close to the converter with short leads. Also
be aware that the output voltage accuracy is ±2% (typical) therefore you may
need to vary this resistance slightly to achieve your desired output setting.
The trim equation is as follows for the LSN-T/16-W3:
LSN-T/16-W3 fi xed resistance values to set the output voltages are:
VOUT (Typ.) 0.75V 1.0V 1.2V 1.5V 1.8V 2.5V 3.3V
RTRIM (kΩ) Open 80.021 41.973 23.077 15.004 6.947 3.16
CAUTION: To retain proper regulation, do not exceed the 3.3V output
Voltage Trim
The LSN-T/16-W3 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 the Trim pin is approximately 5k:. 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 (in Volts) = 0.7 –(0.1698 x (VO – 0.7525))
The LSN-T/16-W3 fi xed trim voltages to set the output voltage are:
VOUT (Typ.) 0.75V 1.0V 1.2V 1.5V 1.8V 2.5V 3.3V
VTRIM Open 0.6928V 0.624V 0.5731V 0.5221V 0.4033V 0.267V
Output Reverse Conduction
Many DC/DC’s 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.
Trim
Down
LOAD
+INPUT
COMMON
+OUTPUT
TRIM
COMMON
Trim
Up
Note: Install either a fixed
trim-up resistor or a fixed
trim-down resistor depending
on desired output voltage.
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Figure 7. Trim Connections Using Fixed Resistors
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/qC to ensure stability.
The equations below can be starting points for selecting specifi c trim-resistor
values. Recall, untrimmed devices are guaranteed to be ±1% accurate.
Trim Equations
Note: Resistor values are in k:. Accuracy of adjustment is subject to toler-
ances of resistors and factory-adjusted, initial output accuracy. VO = desired
output voltage. VONOM = nominal output voltage.
Single Output LSN-W3 Models
Non-Isolated, 3-5.5VIN, 0.75-3.3VOUT
16 Amp DC/DC Converters
www.murata-ps.com email: sales@murata-ps.com
10 Dec 2009 MDC_LSN W3 Models.A02 Page 6 of 8
LSN W3 DC/DC converters do not suffer from Output Reverse Conduction.
They employ proprietary gate drive circuitry that makes them immune to
moderate applied output overvoltages.
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 LSN W3 Series 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 LSN W3’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 varying the load
to keep that temperature below +110°C under the assorted conditions 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, LSN W3’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 LSN W3’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 tempera-
ture to ensure it remains below +110°C at all times.
n
,3.7-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
6).6
/UTPUT#URRENT!MPS
!MBIENT4EMPERATUREo#
LFM
LFM
20 Amps Extended Operation
Under restricted conditions, the LSN W3 models with low output voltages
may produce up to 20 Amps of output current up to approximately +45°C
ambient temperature. There is no model number change. The Derating
curve illustrates typical performance. For this test, the converter was
mounted on a 12cm x12cm double-sided pc board with 2 ounce copper.
This 20 Amp operation is available with the following restrictions:
• Only 1.2 Volt and 1.5 Volt output models are verifi ed for operation at
this time.
• The user must assure that there is adequate airfl ow at all times with
no airfl ow blockage by other large components. Make sure no adjacent
components have high temperatures. Be aware of systems using a
CPU temperature monitor to control the fan.
• Use only low to moderate ambient temperature.
• The user must assure that the total output power is not exceeded.
• This operation applies only to nominal input line voltage. Since effi -
ciency degrades at low line voltage, internal heat dissipation increases,
thereby exceeding the maximum output power.
The Derating curve is drawn where the hot spot on the converter (usually
a power FET) reaches approximately +115°C. Although operation is possible
slightly beyond this point, DATEL strongly advises using this as the maxi-
mum temperature for greatest reliability.
Do not forget that a small overcurrent glitch while running 20 Amps output
could instantly shut down the converter using the Over Current sensor. This
margin of safety is considerably wider at 16 Amps maximum current. Make
sure your output current usage is smooth!! If you are in doubt, contact DATEL
to discuss your application.
Product Adaptations
Murata Power Solutions offers variations of our core product family. These
products are available under scheduled quantity orders and may also include
separate manufacturing documentation from a mutually-agreeable Product
Specifi cation. Since these product adaptations largely share a common parts
list, similar specifi cations and test methods with their root products, they are
provided at excellent costs and delivery. Please contact MPS for details.
As of this date, the following product is available:
LSN-T/16-W3HHL2-Y
This model includes conformal coating added, special pin length and RoHS-5
hazardous substance compliance (with lead).
Single Output LSN-W3 Models
Non-Isolated, 3-5.5VIN, 0.75-3.3VOUT
16 Amp DC/DC Converters
www.murata-ps.com email: sales@murata-ps.com
10 Dec 2009 MDC_LSN W3 Models.A02 Page 7 of 8
Typical Performance Curves
n
,3.47-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
6/5466).6
/UTPUT#URRENT!MPS
!MBIENT4EMPERATUREo#
LFM
.ATURAL#ONVECTION
LFM
LFM
,3.47
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT c#6/546
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
,3.47
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT c#6/546
,OAD#URRENT!MPS
%FFICIENCY
6
).
6
6
).
6
6
).
6
Single Output LSN-W3 Models
Non-Isolated, 3-5.5VIN, 0.75-3.3VOUT
16 Amp DC/DC Converters
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. © 2009 Murata Power Solutions, Inc.
www.murata-ps.com/locations email: sales@murata-ps.com
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
10 Dec 2009 MDC_LSN W3 Models.A02 Page 8 of 8
