LSM-1.8 [MURATA]
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT 10 Amp DC/DC’s in SMT Packages; 单路输出，非隔离， 3.3VIN ， 0.8-2.5VOUT 10安培的DC / DC的SMT封装
| 型号： | LSM-1.8 |
| 厂家： | 
muRata |
| 描述： | Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT 10 Amp DC/DC’s in SMT Packages |
| 文件： | 总13页 (文件大小：438K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
Typical Unit
DATEL's LSM D3 Series for SMT (surface-mount) are non-isolated DC/DC
converters that accept a 3.3V input (3.0V to 3.6V input range) and deliver 1V, 1.2V,
1.5V, 1.8V, 2V or 2.5V outputs at 10 Amps. LSM D3 SMT's are designed to take on-
board 3.3V power and convert it, with the highest efficiency in the smallest space, to
any lower voltage required by today's current-hungry DSP's, ASIC's and CPLD's.
The LSM D3's miniature size makes them ideal for true point-of-use/load power
processing. They occupy a mere 0.7 square inches (4.5 cm2) and are only 0.34
inches (8.64 mm) high. The SMT package is designed for pick and place including
lead free reflow soldering, and they typically require no additional external compo-
nents.
The LSM's best-in-class power density is achieved with a fully synchronous,
fixed-frequency (300kHz), buck topology that also delivers: high efficiency (94% for
2.5VOUT models), low noise (30mVp-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 and over-temperature protection, an output-voltage trim function, a remote on/
off control pin (pull low to disable), and a sense pin. High efficiency enables the LSM
D3's to deliver rated output currents of 10 Amps at ambient temperatures to +70°C
with no air flow (natural convection).
If your low-voltage, high-current requirements have made the use of inefficient
linear regulators impractical, take a look at one of DATEL's easy-to-use, low-cost
LSM SMT's (or equivalent LSN SIP's). All devices are UL/IEC/EN60950 certified and
EMC compliant. UL, CB, HALT and EMC reports are available upon request.
Features
N
Step-down buck regulators with
industry-standard SMT footprint
N
N
N
3.3V input (3.0-3.6V range)
0.8/1/1.2/1.5/1.8/2/2.5VOUT @10A
Non-isolated, fixed-frequency,
synchronous-rectifier topology
N
N
N
N
N
N
N
N
N
N
N
Tape and reel SMT package
1ꢀ setpoint accuracy
Efficiencies to 94ꢀ @ 10 Amps
Noise as low as 30mVp-p
Stable no-load operation
Remote on/off control
Sense pin and output voltage trim
Thermal shutdown
No derating to +70°C, natural convection
UL/IEC/EN60950 certified
EMC compliant
+OUTPUT
(4)
+INPUT
(2)
+SENSE
(6)
~
COMMON
(3)
COMMON
(3)
CURRENT
SENSE
V
CC
PWM
ON/OFF
CONTROL
(1)
REFERENCE &
ERROR AMP
CONTROLLER
V
TRIM
(5)
OUT
~ For devices with the sense-pin removed ("B" suffix),
the feedback path is through the +Output pin and not
the +Sense pin.
Figure 1. Simplified Schematic
Typical topology is shown
For full details go to
www.murata-ps.com/rohs
www.murata-ps.com
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
MDC_LSM-10A D3.B01 Page 1 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
Performance Specifications and Ordering Guide ~
Output
Input
Efficiency
Full Load
Package
(Case,
Pinout)
½ Load
Typ.
R/N (mVp-p)
Regulation (Max.)
VIN Nom.
(Volts)
Range
(Volts)
IIN
(mA/A)
VOUT
(Volts)
IOUT
(Amps)
Model
Typ.
Max.
Line
Load
Min.
Typ.
LSM-0.8/10-D3
LSM-1/10-D3
0.8
1
10
10
10
10
10
10
10
30
30
30
30
30
30
30
50
50
50
50
50
50
50
0.1ꢀ
0.1ꢀ
0.1ꢀ
0.1ꢀ
0.1ꢀ
0.1ꢀ
0.1ꢀ
0.25ꢀ
0.25ꢀ
0.25ꢀ
0.25ꢀ
0.25ꢀ
0.25ꢀ
0.25ꢀ
3.3
3.3
3.3
3.3
3.3
3.3
3.3
3-3.6
3-3.6
3-3.6
3-3.6
3-3.6
3-3.6
3-3.6
70/3.0
70/3.52
70/4.13
70/5.05
70/5.96
70/6.55
70/8.1
81ꢀ
84ꢀ
84ꢀ
86ꢀ
85ꢀ
90ꢀ
91ꢀ
92ꢀ
93ꢀ
94ꢀ
95ꢀ
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
LSM-1.2/10-D3
LSM-1.5/10-D3
LSM-1.8/10-D3
LSM-2/10-D3
1.2
1.5
1.8
2
86ꢀ
88ꢀ
88ꢀ
90ꢀ
89.5ꢀ
90.5ꢀ
91.5ꢀ
91.5ꢀ
92.5ꢀ
93.5ꢀ
LSM-2.5/10-D3
2.5
~
Typical at TA = +25°C under nominal line voltage and full-load conditions, 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
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.
Nominal line voltage, no-load/full-load conditions.
Contact DATEL for availability.
Noise Reduction.
external filtering. See I/O Filtering and Noise Reduction for details.
Ripple/Noise (R/N) is tested/specified over a 20MHz bandwidth and may be reduced with
P A R T N U M B E R S T R U C T U R E
M E C H A N I C A L S P E C I F I C A T I O N S
L SM
- 1.8 / 10- D3 -C
Output
ꢉꢁꢂꢀ
ꢄꢂꢂꢁꢀꢊꢇ
Configuration:
L = Unipolar
Low Voltage
RoHS-6 compliant*
ꢀꢁꢂꢃ
ꢄꢅꢁꢆꢃꢇ
Non-Isolated SMT
Nominal Output Voltage:
0.8, 1, 1.2, 1.5, 1.8, 2,
or 2.5 Volts
Input Voltage Range:
D3 = 3.0 to 3.6 Volts
(3.3V nominal)
ꢀꢁꢀꢅꢈ
ꢄꢊꢁꢉꢆꢇ
3-4 #/00%2 ,%!$3
#/0,!.!2 ꢀꢁꢀꢀꢃ
Maximum Rated Output
Current in Amps
ꢀꢁꢈꢌꢀ ꢄꢉꢃꢁꢃꢅꢇ
ꢀꢁꢂꢉꢀ
ꢄꢌꢁꢅꢌꢇ
ꢂ %1ꢁ 3 ꢁ
ꢀꢁꢉꢋꢀ ꢄꢃꢁꢅꢂꢇ
Note: Not all model number
combinations are available.
Contact Murata Power Solutions (DATEL).
ꢁ
ꢂ
ꢃ
ꢄ
ꢀꢁꢈꢂ
ꢄꢉꢂꢁꢃꢆꢇ
ꢀꢁꢀꢆꢊ
ꢄꢉꢁꢈꢌꢇ
ꢀꢁꢃꢅ
ꢄꢉꢊꢁꢉꢋꢇ
Case C45
ꢀ
ꢅ
49
ꢁ
1.36
(34.54)
"/44/- 6)%7
ꢀꢁꢀꢈ
ꢄꢉꢁꢊꢌꢇ
ꢀꢁꢀꢌꢈ
ꢄꢉꢁꢋꢉꢇ
ꢀꢁꢉꢉꢊ
ꢄꢊꢁꢅꢃꢇ
ꢉꢁꢉꢌꢌ
ꢄꢊꢋꢁꢋꢀꢇ
ꢀꢁꢀꢃꢅ
ꢄꢉꢁꢊꢊꢇ
49
ꢁ
0.55
(13.97)
ꢀꢁꢈꢌꢀ ꢄꢉꢃꢁꢃꢅꢇ
ꢂ %1ꢁ 3 ꢁ
ꢀꢁꢉꢋꢀ ꢄꢃꢁꢅꢂꢇ
ꢀꢁꢊꢋꢌ
ꢄꢌꢁꢈꢃꢇ
ꢀꢁꢂꢉꢀ
ꢄꢌꢁꢅꢌꢇ
0.60
(15.24)
0.010
(0.254)
0.570 (14.48)
3 EQ. SP. @
0.190 (4.83)
DIMENSIONS ARE IN INCHES (MM)
ꢄ
ꢃ
ꢂ
ꢁ
ꢀꢁꢃꢀꢈ
ꢄꢉꢀꢁꢊꢋꢇ
ꢀꢁꢃꢂꢀ
ꢄꢉꢀꢁꢋꢊꢇ
0.375
(9.53)
0.310
(7.87)
0.052
(1.32)
ꢀ
ꢅ
2%#/--%.$%$ 0!$ ,!9/54
3
4
5
6
0.062
(1.57)
2ECOMMENDED 0AD 3IZEꢍ ꢀꢁꢉꢈ X ꢀꢁꢉꢀ ꢄꢂꢁꢅꢉ X ꢊꢁꢈꢃꢇ
2
1
I/O Connections
Pin
1
2
3
4
Function P63
On/Off Control
+Input
Common
+Output
0.112 TYP.
(2.84)
0.047
(1.19)
0.052
(1.32)
0.049
(1.24)
CAUTION
BOTTOM VIEW
PRESS TO REMOVE
THE HEAT SHIELD
AFTER THE SOLDER
PROCESS
LSM WITH REMOVEABLE HEAT SHIELD
FOR HIGH TEMPERATURE SOLDER
Refer to the last page for
5
6
VOUT Trim
+Sense
Tape and Reel information.
NOTCH IN SHELL
INDICATES PIN ONE
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Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
MDC_LSM-10A D3.B01 Page 2 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
Absolute Maximum Ratings
Performance/Functional Specifications
Typical @ TA = +25°C under nominal line voltage and full-load conditions unless noted. ~
Input Voltage:
Input
Continuous or transient
6 Volts
Input Voltage Range
4.5 to 5.5 Volts (5V nominal)
On/Off Control (Pin 1)
+VIN
Input Current:
Normal Operating Conditions
Inrush Transient
Input Reverse-Polarity Protection
Output Overvoltage Protection
Output Current
None
See Ordering Guide
0.01A2sec
8mA
None
Current limited. Devices can
Standby/Off Mode
Output Short-Circuit Condition
110mA average
withstand sustained output
circuits
short
without damage.
Input Reflected Ripple Current
Input Filter Type
10mAp-p
Capacitive (44μF)
None
Storage Temperature
–40 to +125°C
Overvoltage Protection
Reverse-Polarity Protection
Undervoltage Shutdown
On/Off Control
Lead Temperature (soldering, 10 sec.)
See Reflow Solder Profile
None
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 Specifications Table is not implied.
None
On = open (internal pull-up to +VIN)
Off = 0 to +0.8V (1ma max.)
Output
VOUT Accuracy (50ꢀ load)
Minimum Loading ~
Maximum Capacitive Load
VOUT Trim Range
1ꢀ maximum
T E C H N I C A L N O T E S
No load
1000μF (low ESR, OSCON)
10ꢀ (0.8V not trimmable)
See Ordering Guide
3ꢀ over line/load temperature
See Ordering Guide
I/O Filtering and Noise Reduction
All models in the LSM D3 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 D3'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.
Ripple/Noise (20MHz BW) ~
Total Accuracy
Efficiency
Overcurrent Detection and Short-Circuit Protection:
Current-Limiting Detection Point
Short-Circuit Detection Point
SC Protection Technique
Short-Circuit Current
17 (13-23.5) Amps
98ꢀ of VOUT set
Hiccup with auto recovery
600mA average
In particular, the LSM D3'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. As shown in the Performance Curves, removal of the external
22μF tantalum output caps has minimal effect on output noise.
Dynamic Characteristics
Transient Response (50ꢀ load step)
100μsec to 2ꢀ of final value
Start-Up Time:
VIN to VOUT
On/Off to VOUT
7msec
6msec
In critical applications, input/output ripple/noise may be further reduced using
filtering techniques, the simplest being the installation of external I/O caps.
Switching Frequency:
300kHz (+40/–50kHz)
Environmental
2.3-1.8 million hours (1VOUT to 5VOUT)
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 appropriate 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 induc-
tive source impedances can greatly affect system stability. Your specific
system configuration may necessitate additional considerations.
Calculated MTBF
Operating Temperature: (Ambient)
Without Derating (Natural convection) –40 to +65/71°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)
UL94V-0
Flammability Rating
Safety
4/
#522%.4
02/"%
/3#),,/3#/0%
UL/cUL/IEC/EN 60950,
CSA-C22.2 No. 60950
ꢊ
ꢂ
ꢑ).054
,
"53
~
All models are tested and specified with external 22μF tantalum input and output capacitors.
ꢑ
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.
6
).
#
"53
#).
n
See Technical Notes and Performance Curves for details.
The On/Off Control (pin 1) is designed to be driven with open-collector logic or the appli-
cation 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.
Output noise may be further reduced with the installation of additional external output
filtering. See I/O Filtering and Noise Reduction.
MTBF’s are calculated using Telcordia SR-332(Bellcore), ground fixed, TA = +25°C, full
power, natural convection, +67°C pcb temperature.
#/--/.
#
). ꢎ ꢂꢂ§&ꢏ %32 ꢐ ꢌꢀꢀM7 ꢉꢀꢀK(Z
"53 ꢎ ꢊꢊꢀ§&ꢏ %32 ꢐ ꢉꢀꢀM7 ꢉꢀꢀK(Z
#
,
"53 ꢎ ꢉꢊ§(
Figure 2. Measuring Input Ripple Current
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Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
MDC_LSM-10A D3.B01 Page 3 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
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 appro-
priate frequency 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 D3 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 VIN to VOUT Start-Up Time is the interval between the time at which a
ramping input voltage crosses the lower limit of the specified input voltage
range (3 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.
6
COPPER STRIP
+SENSE
4
+OUTPUT
R
LOAD
SCOPE
C1
C2
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 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.
3
COMMON
COPPER STRIP
C1 = NA
C2 = 22μF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE
Remote Sense
LSM D3 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.
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.
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
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 tech-
niques should be used. To prevent high frequency voltage differences between
VOUT and Sense, we recommend installation of a 1000pF capacitor close to
the converter.
The 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. Our Applications Engineers can recommend potential solu-
tions and discuss the possibility of our modifying a given device’s internal filter-
ing to meet your specific requirements. Contact our Applications Engineering
Group for additional details.
Input Fusing
The sense function is capable of compensating for voltage drops between the
+Output and +Sense pins that do not exceed 10ꢀ of VOUT.
Most applications and or safety agencies require the installation of fuses at
the inputs of power conversion components. LSM D3 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 17 Amps should
be installed within the ungrounded input path to the converter.
[VOUT(+) – Common] – [Sense(+) – Common] b 10ꢀVOUT
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 func-
tions can cause the output voltage to increase, thereby increasing output
power beyond the LSM's specified rating. Therefore:
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.
(VOUT at pins) x (IOUT) b rated output power
Safety Considerations
The internal 10.57 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.
LSM D3 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 speci-
fications (usually UL/IEC/EN60950).
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.
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.
For the "B" model number option (sense pad removed), the sense is internally
connected to +VOUT.
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MDC_LSM-10A D3.B01 Page 4 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
On/Off Control
+INPUT
The On/Off Control pin may be used for remote on/off operation. LSM D3
Series DC/DC converters are designed so that they are enabled when the
control pin is left open (open collector) and disabled when the control pin is
pulled low (to less than +0.8V relative to Common). As shown in Figure 4, all
models have an internal 5k7 pull-up resistor to VIN (+Input).
5kꢀ
10kꢀ
EXTERNAL
OPEN
COLLECTOR
INPUT
Dynamic control of the on/off function is best accomplished with a mechanical
relay or open-collector/open-drain drive circuit (optically isolated if appropri-
ate). The drive circuit should be able to sink appropriate current when
activated and withstand appropriate voltage when deactivated.
COMMON
External Input Open:
External Input Low:
On/Off pin Low = DC/DC converter Off
On/Off pin High = DC/DC converter On
Figure 5. Driving the External Power-Up Open Collector
ꢑ).054
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 D3 SMT Series
DC/DC converters incorporate an output overcurrent detection and shutdown
function that serves to protect both the power converter and its load.
/.ꢒ/&&
#/.42/,
#/--/.
ON/OFF pin open:
ON/OFF pin <0.4V:
Logic High = DC/DC converter On
Logic Low = DC/DC converter Off
If the output current exceeds it maximum rating by typically 70ꢀ (17 Amps) or
if the output voltage drops to less than 98ꢀ of it original value, the LSM D3'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
600mA, and the average input current will be approximately 110mA. Once the
output short is removed, the converter will automatically restart itself.
Figure 4. Driving the On/Off Control Pin with an Open-Collector Drive Circuit
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).
Output Voltage Trimming
Allowable trim ranges for each model in the LSM D3 SMT Series are 10ꢀ.
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.
Power-up sequencing
If a controlled start-up of one or more LSM D3 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.
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/oC to ensure stability.
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.
The equations below can be starting points for selecting specific trim-resistor
values. Recall, untrimmed devices are guaranteed to be p1ꢀ accurate.
Output Overvoltage Protection
LSM D3 SMT Series DC/DC converters do not incorporate output overvolt-
age 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.
Adjustment beyond the specified 10ꢀ adjustment range is not recommended.
When using trim in combination with Remote Sense, the maximum rated power
must not be exceeded (see Remote Sense).
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MDC_LSM-10A D3.B01 Page 5 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
Output Reverse Conduction
Many DC/DC's using synchronous rectification 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.
ꢑ/54054
42)-
ꢑ).054
ꢊꢀK7
ꢈꢓꢉꢀ
4URNS
,/!$
#/--/.
#/--/.
LSM D3 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.
Figure 6. Trim Connections Using a Trimpot
Thermal Considerations and Thermal Protection
ꢑ/54054
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 D3 SMT's under known ambient-temperature and air-flow
conditions. Similarly, the curves indicate how much air flow is required to
reliably deliver a specific output current at known temperatures.
Note:
Install either a fixed
trim-up resistor
or a fixed trim-down
resistor depending upon
desired output voltage.
4RIM
$OWN
ꢑ).054
42)-
,/!$
4RIM
5P
#/--/.
The highest temperatures in LSM D3 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
varying the load to keep that temperature below +110°C under the assorted
conditions of air flow 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.
#/--/.
Figure 7. Trim Connections Using Fixed Resistors
Trim Equations
Trim Equations
Model
As you may deduce from the derating curves and observe in the efficiency
curves on the following pages, LSM D3 SMT's are more efficient at lower
current levels. Also I2R losses in the output inductor are significantly less at
lower current levels. Consequently, LSN-D3 SMT's deliver very impressive
temperature performance if operating at less than full load.
1.62(VO – 0.8)
RTDOWN (k7) =
– 1
1 – VO
LSM-1/10-D3
1.296
– 1
RTUP (k7) =
VO – 1
Lastly, when LSM D3 SMT's are installed in system boards, they are obvi-
ously 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.
2.49(VO – 0.8)
1.2 – VO
– 2.37
RTDOWN (k7) =
RTUP (k7) =
LSM-1.2/10-D3
1.992
– 2.37
VO – 1.2
2.37(VO – 0.8)
VO NOM – VO
– 4.99
RTDOWN (k7) =
RTUP (k7) =
LSM-1.5/10-D3
LSM-1.8/10-D3
LSM-2/10-D3
1.896
– 4.99
LSM-2.5/10-D3
VO – VO
NOM
Note: Resistor values are in k7. 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-D3 is not trimmable.
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MDC_LSM-10A D3.B01 Page 6 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
Start Up Considerations
Solutions
When power is first applied to the DC/DC converter, operation is different
than when the converter is running and stabilized. There is some risk of start
up difficulties if you do not observe several application features. Lower input
voltage 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:
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 sup-
plies the surge current and a smaller parallel low-ESR ceramic cap gives low
AC impedance. 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 controller. Make sure the capacitors can tolerate reflected switching
current pulses from the converter.
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.
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 capaci-
tance.
4 – Longer distance to input voltage source and/or higher external input
source impedance.
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.
5 - Limited or insufficient 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 termi-
nals to below the specified minimum voltage. Even if this voltage depression
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.
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 reactance in the load. Certain kinds of electronic loads include
“constant current” characteristics which destabilize the output with insufficient
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.
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.
An elegant solution to start up problems is to apply the input voltage with the
Remote On/Off control first in the off setting (for those converters with an
On/Off Control). After the specified 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).
Symptoms of start-up difficulties may include failed started, output oscillation
or brief start up then overcurrent shutdown. Since the input voltage is never
absolutely constant, the converter may start up at some times and not at
others.
Finally, it is challenging to model some application circuits with absolute fidel-
ity. How low is the resistance of your ground plane? What is the inductance
(and distributed capacitance) of external wiring? Even a detailed mathemati-
cal model may not get all aspects of your circuit. Therefore it is difficult to
give cap values which serve all applications. Some experimentation may be
required.
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MDC_LSM-10A D3.B01 Page 7 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
Typical Performance Curves for LSM-10A D3 SMT Series
LSM-1/10-D3
LSM-1.8/10-D3
Efficiency vs. Line Voltage and Load Current
Efficiency vs. Line Voltage and Load Current
91
89
87
85
83
81
79
77
75
95
94
93
92
91
90
89
88
87
V
IN = 3V
V
IN = 3V
V
IN = 3.3V
VIN = 3.3V
V
IN = 3.6V
VIN = 3.6V
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
Load Current (Amps)
Load Current (Amps)
LSM-1.2/10-D3
Efficiency vs. Line Voltage and Load Current
LSM-2/10-D3
Efficiency vs. Line Voltage and Load Current
92
90
88
86
84
82
80
95
94
93
92
91
90
89
88
87
V
IN = 3V
V
IN = 3V
V
IN = 3.3V
VIN = 3.3V
V
IN = 3.6V
V
IN = 3.6V
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
Load Current (Amps)
Load Current (Amps)
LSM-1.5/10-D3
Efficiency vs. Line Voltage and Load Current
LSM-2.5/10-D3
Efficiency vs. Line Voltage and Load Current
94
93
92
91
90
89
88
87
86
85
97
96
95
94
93
92
91
90
V
IN = 3V
V
IN = 3V
V
IN = 3.3V
VIN = 3.3V
V
IN = 3.6V
VIN = 3.6V
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
Load Current (Amps)
Load Current (Amps)
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MDC_LSM-10A D3.B01 Page 8 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
Typical Performance Curves for LSM-10A D3 SMT Series
LSM-1/10-D3 & LSM-1.2/10-D3
LSM-1.5/10-D3
Output Current vs. Ambient Temperature
(SMT mount, air flow direction from pin 2 to pin 1)
Output Current vs. Ambient Temperature
(SMT mount, air flow direction from pin 2 to pin 1)
10
8
10
8
Natural Convection
Natural Convection
6
6
100 lfm
100 lfm
200 lfm
4
4
200 lfm
2
2
0
–40
0
–40
0
60
70
80
90
100
110
0
60
70
80
90
100
110
Ambient Temperature (oC)
Ambient Temperature (oC)
LSM-2.5/10-D3
Output Current vs. Ambient Temperature
(SMT mount, air flow direction from pin 2 to pin 1)
LSM-1.8/10-D3 & LSM-2/10-D3
Output Current vs. Ambient Temperature
(SMT mount, air flow direction from pin 2 to pin 1)
10
8
10
8
Natural Convection
Natural Convection
6
6
100 lfm
100 lfm
4
4
200 lfm
200 lfm
2
2
0
–40
0
–40
0
60
70
80
90
100
110
0
60
70
80
90
100
110
Ambient Temperature (oC)
Ambient Temperature (oC)
Input Inrush Current
(VIN = 3.3V, 6600μF as Input Switch)
Input Reflected Ripple Current
(VIN = 3.3V, VOUT = 2V/10A, Input Filter = 220μF/12μH/33μF)
5A/div
50mA/div
20μsec/div
1μsec/div
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MDC_LSM-10A D3.B01 Page 9 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
Typical Performance Curves for LSM-10A D3 SMT Series at VIN = 3.3V
Start-Up from ON/OFF
Start-Up from ON/OFF
(IOUT = 1V/10A, CIN/COUT = 22μF)
(IOUT = 2V/10A, CIN/COUT = 22μF)
VIN
2V/div
VIN
2V/div
VOUT
1V/div
VOUT
1V/div
2msec/div
2msec/div
Start-Up from VIN
Start-Up from VIN
(IOUT = 1V/10A, CIN/COUT = 22μF)
(IOUT = 2V/10A, CIN/COUT = 22μF)
VIN
2V/div
VIN
2V/div
VOUT
1V/div
VOUT
1V/div
2msec/div
2msec/div
Output Hiccup
Output Hiccup
(LSM-1/10-D3, Shorted VOUT)
(LSM-2/10-D3, Shorted VOUT)
100mV/div
100mV/div
4msec/div
4msec/div
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MDC_LSM-10A D3.B01 Page 10 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
Typical Performance Curves for LSM-10A D3 SMT Series at VIN = 3.3V
Output Ripple and Noise
Output Ripple and Noise
(VOUT = 2V/10A, CIN/COUT = 22μF, BW = 20MHz)
(VOUT = 1V/10A, CIN/COUT = 22μF, BW = 20MHz)
20mV/div
20mV/div
1μsec/div
1μsec/div
Dynamic Load Response
Dynamic Load Response
(VOUT = 2V, 5 to 10A Step, CIN/COUT = 22μF)
(VOUT = 2V, 5 to 10A Step, CIN = 22μF, COUT = 1000μF Oscon)
50mV/div
50mV/div
100μsec/div
100μsec/div
Dynamic Load Response
Dynamic Load Response
(VOUT = 1V, 5 to 10A Step, CIN/COUT = 22μF)
(VOUT = 1V, 5 to 10A Step, CIN = 22μF, COUT = 1000μF Oscon)
50mV/div
50mV/div
100μsec/div
100μsec/div
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MDC_LSM-10A D3.B01 Page 11 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
Tape & Reel Surface Mount Package
DATEL's 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 reflowed using high-temperature, lead-free solder.
DATEL is not exempted from the Laws of Physics, and we do not have magic
solders no one else has. Nevertheless, we have a simple and practical,
straightforward approach that works. We assemble our LSM SMT DC/DC's
using a high-temperature (+216°C), lead-free alloy (Sn96.2ꢀ, Ag2.5ꢀ,
Cu0.8ꢀ, Sb0.5ꢀ). The LSM design ensures co-planarity to within 0.004
inches (100μ1m) of the unit's copper leads. These leads are gold-plated with
a nickel underplate. See Mechanical Data for additional information.
Virtually all SMT DC/DC's 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 melt-
ing point of +183°C). Conceptually straightforward, this "stepped" solder
approach has its limitations, and it is clearly out of step with an industry
trending toward the broad use of lead-free solders. Are you to experiment
and develop reflow profiles from other vendors that ensure the components
on those DC/DC never exceed 215-216°C? If those components get too hot,
"double-reflow" could compromise the reliability of their solder joints. Virtually
all these devices demand you "cool down" the Sn63 profile you are likely
using today.
The disposable heat shield (patent pending), which has a cutaway exposing
the package leads, provides thermal insulation to internal components during
reflow and its smooth surface ideally doubles as the vacuum pick-up location
also. The insulation properties of the heat shield are so effective that tem-
perature differentials as high as 50°C develop inside-to-outside the shield.
Oven temperature profiles with peaks of 250-260°C and dwell times exceed-
ing 2 minutes above 221°C (the melting point of Sn96.5/Ag3.5) are easily
achieved.
HEAT SHIELD OUTSIDE TEMPERATURE
250
Sn96.5/Ag3.5 Melting Point
221
200
183
Sn63/Pb37 Melting Point
150
PCB TEMPERATURE INSIDE THE HEAT SHIELD
100
50
0
50
100
150
200
250
300
350
400
Time (Seconds)
Figure 6. Reflow Solder Profile
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MDC_LSM-10A D3.B01 Page 12 of 13
LSM-10A D3 Models
Single Output, Non-Isolated, 3.3VIN, 0.8-2.5VOUT
10 Amp DC/DC’s in SMT Packages
DATEL's new-generation LSM SMT DC/DC converters are shipped in quantities of 150 modules per tape and reel.
1.102
(28)
0.158
(4)
CENTERED
PICK UP
LOCATION
NOTCH IN SHELL
INDICATES
PIN ONE.
CAUTION
PRESS TO REMOVE
THE HEAT SHIELD
AFTER THE SOLDER
PROCESS.
2.063
(52.4)
2.205
(56)
1.370
(34.8)
FEED
1
1
1
DIRECTION
TAPE
DIMENSIONS
IN INCHES (mm)
0.590
(14.97)
0.605
(15.36)
Figure 7. Tape Dimensions
2.44
(62.0)
13.0 (330.2)
7.38 (187.5)
0.51(13.0)
Figure 8. Reel Dimensions
USA:
Tucson (Az), Tel: (800) 547 2537, email: sales@murata-ps.com
Canada: Toronto, Tel: (866) 740 1232, email: toronto@murata-ps.com
UK: Milton Keynes, Tel: +44 (0)1908 615232, email: mk@murata-ps.com
Murata Power Solutions, Inc.
France: Montigny Le Bretonneux, Tel: +33 (0)1 34 60 01 01, email: france@murata-ps.com
Germany: München, Tel: +49 (0)89-544334-0, email: munich@murata-ps.com
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356
www.murata-ps.com email: sales@murata-ps.com ISO 9001 REGISTERED
Japan: Tokyo, Tel: 3-3779-1031, email: sales_tokyo@murata-ps.com
Osaka, Tel: 6-6354-2025, email: sales_osaka@murata-ps.com
Website: www.murata-ps.jp
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. Specifications are subject to change without
China:
Shanghai, Tel: +86 215 027 3678, email: shanghai@murata-ps.com
Guangzhou, Tel: +86 208 221 8066, email: guangzhou@murata-ps.com
notice.
© 2008 Murata Power Solutions, Inc.
03/05/08
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MDC_LSM-10A D3.B01 Page 13 of 13
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