LSM-10A D12 Models

LSM-10A D12 Models
www.murata-ps.com
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Typical Unit
PRODUCT OVERVIEW
FEATURES

Step-down, wide buck regulators for new
distributed 12V power architectures

12V input (10.8-13.2V range)

0.75 to 5VOUT @10A

Voltage-selectable "T" version

Non-isolated, fixed-frequency,
synchronous-rectifier topology

Tape and reel SMT package

±1.25% setpoint accuracy
 Efficiencies to 96% @ 10 Amps

Stable no-load operation

Remote on/off control

Sense pin and output voltage trim

No derating to +65°C with 100 lfm

UL/IEC/EN60950-1 certification pending

EMC compliant
LSM Series D12 SMT's (surface-mount packages)
are ideal building blocks for emerging, on-board
power-distribution schemes in which isolated
12V buses deliver power to any number of nonisolated, step-down buck regulators. LSM D12
DC/DC's accept a 12V input (10.8V to 13.2V input
range) and convert it, with the highest 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 10 Amps.
LSM D12's are ideal point-of-use/load power
processors. They typically require no external
components. Their surface-mount packages
occupy a mere 1.3" x 0.53" (33.0 x 13.5mm),
and are only 0.34 inches (8.6mm) high.
The LSM's best-in-class power density
is achieved with a fully synchronous, fixedfrequency, buck topology that also delivers:
high efficiency (96% for 5VOUT models), low
noise (50mVp-p typ.), tight line/load regulation
(±0.1%/±0.25% max.), quick step response
(100μsec), stable no-load operation, and no
output reverse conduction.
The fully functional LSM’s feature output 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 10 Amps at ambient temperatures to
+65°C with 100 lfm air flow.
If your new system boards call for three or
more supply voltages, check out the economics
of on-board 12V distributed power. If you don't
need to pay for multiple isolation barriers, Murata
Power Solutions' non-isolated LSM D12 SMT's
will save you money.
+OUTPUT
(4)
+INPUT
(2)
+SENSE
(6)
COMMON
(3)
COMMON
(3)
CURRENT
SENSE
VCC
ON/OFF
CONTROL
(1)
PWM
CONTROLLER
REFERENCE &
ERROR AMP
VOUT
TRIM
(5)
Typical topology is shown
Figure 1. Simplified Schematic
For full details go to
www.murata-ps.com/rohs
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MDC_LSM 10A D12 Models.D02 Page 1 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
PERFORMANCE SPECIFICATIONS SUMMARY AND ORDERING GUIDE ➀
Output
Models
VOUT
(Volts)
IOUT
(Amps)
LSM-0.8/10-D12
LSM-1/10-D12
LSM-1.2/10-D12
LSM-1.5/10-D12
LSM-1.8/10-D12
LSM-2/10-D12
LSM-2.5/10-D12
LSM-3.3/10-D12
LSM-5/10-D12
LSM-T/10-D12
0.8
1
1.2
1.5
1.8
2
2.5
3.3
5
0.75-5
10
10
10
10
10
10
10
10
10
10
R/N (mVp-p) ➁
Input
Regulation (Max.) ➂
Typ.
Max.
Line
Load
VIN Nom.
(Volts)
45
50
50
50
50
50
50
50
75
50
60
75
85
75
75
75
75
75
100
75
±0.1%
±0.1%
±0.2%
±0.1%
±0.1%
±0.1%
±0.1%
±0.1%
±0.3%
±0.1%
±0.375%
±0.25%
±0.65%
±0.25%
±0.25%
±0.25%
±0.25%
±0.7%
±0.95%
±0.25%
12
12
12
12
12
12
12
12
12
12
➀ Typical at TA = +25°C under nominal line voltage and full-load conditions, unless 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.
Efficiency
Range
(Volts)
IIN ➃
(mA/A)
Min.
Typ.
Typ.
Package
(Case,
Pinout)
10.8-13.2
10.8-13.2
10.8-13.2
10.8-13.2
10.8-13.2
10.8-13.2
10.8-13.2
10.8-13.2
10.8-13.2
10-14
30/0.84
35/1.02
40/1.19
50/1.47
55/1.75
55/1.9
60/2.3
70/3
85/4.5
100/6.5
80.5%
83%
85%
86.5%
88%
89%
90%
92%
93.5%
92%
82.5%
85%
87%
88.5%
90%
91%
92.5%
94%
96%
93%
85%
86%
88%
89.5%
90.5%
91.5%
92%
93.5%
95.5%
--
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
C45, P63
Full Load
½ Load
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 LSM-T/10-D12 specifications are given at VOUT = 5V, full load.
PART NUMBER STRUCTURE
L SM - 1.8 / 10 - D12 - C
Output
Configuration:
L = Unipolar
Low Voltage
Non-Isolated SMT
Nominal Output Voltage:
0.8, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3, 5
Volts or "T" voltage selectable
RoHS-6 compliant*
Input Voltage:
D12 = 12V nominal
Maximum Rated Output
Current in Amps
* Contact Murata Power Solutions
for availability.
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MDC_LSM 10A D12 Models.D02 Page 2 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
MECHANICAL SPECIFICATIONS
1.36
(34.54)
I/O Connections
Pin
Function P63
1
On/Off Control
2
+Input
3
Common
4
+Output
5
VOUT Trim
6
+Sense
0.55
(13.97)
0.60
(15.24)
0.010
(0.254)
0.570 (14.48)
3 EQ. SP. @
0.190 (4.83)
0.310
(7.87)
3
0.062
(1.57)
4
5
0.375
(9.53)
0.052
(1.32)
6
2
1
0.112 TYP.
(2.84)
0.049
(1.24)
BOTTOM VIEW
LSM WITH REMOVEABLE HEAT SHIELD
FOR HIGH TEMPERATURE SOLDER
(
)
0.052
(1.32)
CAUTION
PRESS TO REMOVE
THE HEAT SHIELD
AFTER THE SOLDER
PROCESS
%130
490
CAUTION
PRESS TO REMOVE
THE HEAT SHIELD
AFTER THE SOLDER
PROCESS
"/44/-6)%7
%130
NOTCH IN SHELL
INDICATES PIN ONE
DIMENSIONS ARE IN INCHES (MM)
Case C45
490
Refer to the last page for
Tape and Reel information.
3-4#/00%2,%!$3
#/0,!.!2
0.047
(1.19)
2%#/--%.$%$0!$,!9/54
2ECOMMENDED0AD3IZEXX
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MDC_LSM 10A D12 Models.D02 Page 3 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Performance/Functional Specifications
Typical @ TA = +25°C under nominal line voltage and full-load conditions unless noted. ➀
Input
Input Voltage Range
Input Current:
Normal Operating Conditions
Inrush Transient
Standby/Off Mode
Output Short-Circuit Condition
Input Reflected Ripple Current ➁ ➅
Input Filter Type
Overvoltage Protection
Reverse-Polarity Protection
Undervoltage Shutdown
On/Off Control ➁ ➂ ➆
See Ordering Guide
See Ordering Guide
0.08A2 sec
1.5mA
12-40mA average (model dependent)
40mAp-p
Capacitive
None
None
None (except 8V LSM-T/10-D12)
On = open (internal pull-up to +VIN)
Off = 0 to +0.4V (1mA max.)
Output
VOUT Accuracy (50% load)
Minimum Loading ➀
Maximum Capacitive Load
VOUT Trim Range ➇
Ripple/Noise (20MHz BW) ➀ ➁ ➃
±1.25% max. (±2% "T" version, 50% load)
No load
1000µF (low ESR, OSCON)
±10% (0.8V not trimmable)
See Ordering Guide
Total Accuracy
3% over line/load/temperature
Efficiency
See Ordering Guide
Overcurrent Detection and Short-Circuit Protection: ➈
Current-Limiting Detection Point
17 Amps
Short-Circuit Detection Point
98% of VOUT set
SC Protection Technique
Hiccup with auto recovery
Short-Circuit Current
120-400mA average (model dependent)
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, TA = +25°C, full power,
natural convection, +67°C pcb temperature.
➅ Input Ripple Current is tested/specified over a 5-20MHz bandwidth with an external 33µF input
capacitor and a simulated source impedance of 220µF and 12µH. See I/O Filtering, Input
Ripple Current and Output Noise for details.
➆ On/Off Control for LSM-T/10-D12 only: Positive Logic: On = pin open or to +4V max.,
Off = pin grounded or 0 to +0.4V max. Shutdown current is 3µA sink.
➇ The Output Voltage Range for the LSM-T/10-D12 is +0.75V to +5V, user selectable.
➈ LSM-T/10-D12 Overcurrent and Short-circuit specs:
Current limit
25 Amps
Short Circuit Current 600mA
Absolute Maximum Ratings
Input Voltage:
Continuous or transient
15 Volts
On/Off Control (Pin 1)
+VIN (+4V for "T" version)
Input Reverse-Polarity Protection
None
Output Overvoltage Protection
None
Output Current
Current limited. Devices can
withstand sustained output short
circuits without damage.
Storage Temperature
–40 to +125°C
Lead Temperature
See Reflow Solder Profile
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.
Dynamic Characteristics
Transient Response (50% load step)
Start-Up Time: ➁
VIN to VOUT and On/Off to VOUT
Switching Frequency:
0.8V, 1V/1.2V Models
1.5V/1.8V, 2V Models
2.5V, 3.3V, 5V Models
LSM-T/10-D12
115µsec to ±2% of final value
75msec for VOUT = 1V and 0.8V
50msec for VOUT = 1.2V to 5V
105/120kHz ±10%
160/177kHz ±10%
195kHz ±10%
230kHz ±30kHz
Environmental
Calculated MTBF ➄
2.3-1.8 million hours (1VOUT to 5VOUT)
Operating Temperature: (Ambient) ➁
Without Derating (100 lfm)
–40 to +48/64°C (model dependent)
With Derating
See Derating Curves
Thermal Shutdown
+115°C (110 to 125°C)
Physical
Dimensions
1.3" x 0.53" x 0.34" (33.02 x 13.46 x 8.64 mm)
Pin Dimensions/Material
0.112" x 0.062" (2.84 x 1.57mm) rectangular
copper with gold plate over nickel underplate
Weight
0.28 ounces (7.8g)
Flamability Rating
UL94V-0
EMI
Conducted and radiated FCC part 15,
EN55022 (may require external filter)
Safety
UL/cUL/IEC/EN 60950-1, CSA-C22.2 No. 234
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 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.
TECHNICAL NOTES
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 D12'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.
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 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 inductive source impedances can greatly affect system stability. Your specific system configuration
may necessitate additional considerations.
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MDC_LSM 10A D12 Models.D02 Page 4 of 18
MDC_LSM10AD12_A01 Page 4 of 14
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
4/
/3#),,/3#/0%
#522%.4
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ers are not internally fused. Therefore, if input fusing is mandatory, either a
normal-blow or a fast-blow fuse with a value no greater than 20 Amps should
be installed within the ungrounded input path to the converter.
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6).
#"53
#).
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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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/separation requirements, in compliance with relevant safety-agency specifications
(usually UL/IEC/EN60950-1).
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 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.
+SENSE
+OUTPUT
6
COPPER STRIP
4
C1
COMMON
C2
SCOPE
RLOAD
3
COPPER STRIP
C1 = NA
C2 = 22µF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE
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 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
solutions and discuss the possibility of our modifying a given device’s internal
filtering to meet your specific requirements. Contact our Applications Engineering Group for additional details.
Input Fusing
Most applications and or safety agencies require the installation of fuses at
the inputs of power conversion components. LSM D12 Series DC/DC convert-
In particular, for a non-isolated converter's output voltage to meet SELV
(safety extra low voltage) requirements, its input must be SELV compliant. If the
output needs to be ELV (extra low voltage), the input must be ELV.
Input Overvoltage and Reverse-Polarity Protection
LSM D12 SMT Series DC/DCs do not incorporate either input overvoltage or
input reverse-polarity protection. Input voltages in excess of the specified
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 ramping 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 voltage 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 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
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 lowimpedance 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.
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MDC_LSM 10A D12 Models.D02 Page 5 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
The sense function is capable of compensating for voltage drops between
the +Output and +Sense pins that do not exceed 10% of VOUT.
[VOUT(+) – Common] – [Sense(+) – Common] ≤ 10%VOUT
Power derating (output current limiting) is based upon maximum output current 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:
).054
/./&&
#/.42/,
§!
333$
07-
(VOUT at pins) x (IOUT) ≤ rated output power
The internal 10.5Ω resistor between +Sense and +Output (see Figure 1)
serves to protect the sense function by limiting the output current 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 control pin is left open (open collector) and disabled when the control pin is pulled
low (to less than +0.4V relative to Common). As shown in Figure 4, all models
have an internal pull-up resistor.
Dynamic control of the on/off function is best accomplished with a
mechanical relay or open-collector/open-drain drive circuit (optically isolated if
appropriate). The drive circuit should be able to sink appropriate current when
activated and withstand appropriate voltage when deactivated.
#/--/.
Figure 4A. LSM-T10-D12 Driving the On/Off Control Input
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.
).054
K7
%84%2.!,
/0%.
#/,,%#4/2
).054
#/--/.
).054
External Input Open: On/Off pin Low = DC/DC converter Off
External Input Low: On/Off pin High = DC/DC converter On
Figure 5. Driving the External Power-Up Open Collector
/./&&
#/.42/,
#/--/.
ON/OFF pin open: Logic High = DC/DC converter On
ON/OFF pin <0.4V: Logic Low = DC/DC converter Off
Figure 4. Driving the On/Off Control Pin with an Open-Collector Drive Circuit
(All models except LSM-T/10-D12)
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).
Leaving the input of the external circuit open during power-up will have the
output of the DC/DC converter disabled. When the input to the external open
collector is pulled low, the DC/DC converters output will be enabled.
Output Overvoltage Protection
LSM D12 SMT Series DC/DC converters do not incorporate output overvoltage
protection. In the extremely rare situation in which the device’s feedback loop
is broken, the output voltage may run to excessively high levels (VOUT = VIN). If it
is absolutely imperative that you protect your load against any and all possible
overvoltage situations, voltage limiting circuitry must be provided external to
the power converter.
Output Overcurrent Detection
Overloading the power converter's output for an extended time will invariably
cause internal component temperatures to exceed their maximum ratings and
eventually lead to component failure. High-current-carrying components such
as inductors, FET's and diodes are at the highest risk. LSM D12 SMT Series
DC/DC converters incorporate an output overcurrent detection and shutdown
function that serves to protect both the power converter and its load.
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MDC_LSM 10A D12 Models.D02 Page 6 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
If the output current exceeds it maximum rating by typically 70% or if the
output voltage drops to less than 98% of it original value, the LSM D12's 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. Once
the output short is removed, the converter will automatically restart itself.
Output Voltage Trimming (Except "T" models—See "T" Trimming)
Allowable trim ranges for each model in the LSM D12 SMT Series are ±10%.
The LSM-T/10-D12 has a user-selectable output range of +0.75V to +5V.
Trimming is accomplished with either a trimpot or a single 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.
The following trim equations can be starting points for selecting specific
trim-resistor values. Recall, untrimmed devices are guaranteed to be ±1.25%
accurate.
Adjustment beyond the specified adjustment range is not recommended.
When using trim in combination with Remote Sense, the maximum rated power
must not be exceeded (see Remote Sense).
Trim Equations
RT DOWN (kΩ) =
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RT DOWN (kΩ) =
#/--/.
#/--/.
–X
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.
VO NOM – VO
–X
1.46
VO – VO NOM
–X
X = 0.909
X = 2.49
X = 3.09
X = 4.12
RT UP (kΩ) =
3.72
VO – VO NOM
–X
RT DOWN (kΩ) =
7.5(VO – 0.8)
VO NOM – VO
–X
RT UP (kΩ) =
6
VO – VO NOM
–X
LSM-2.5/10-D12: X = 20
LSM-3.3/10-D12: X = 15
LSM-5/10-D12: X = 10
Note: Resistor values are in kΩ. Accuracy of adjustment is subject to
tolerances of resistors and factory-adjusted, initial output accuracy.
VO = desired output voltage. VONOM = nominal output voltage.
+OUTPUT
Trim
Down
TRIM
4.64(VO – 0.8)
RT UP (kΩ) =
LSM-1.5/10-D12: X = 13.3
LSM-1.8/10-D12: X = 16.9
LSM-2/10-D12: X = 15.4
Figure 6. Trim Connections Using a Trimpot
+INPUT
VO NOM – VO
LSM-1/10-D12:
LSM-1.1/10-D12:
LSM-1.2/10-D12:
LSM-1.3/10-D12:
/54054
42)-
1.82(VO – 0.8)
LOAD
Note: LSM-0.8/10-D12 is not trimmable.
Trim
Up
COMMON
COMMON
Note: Install either a fixed
trim-up resistor or a fixed
trim-down resistor depending
upon desired output voltage.
Figure 7. Trim Connections Using Fixed Resistors
"T" Model, LSM-T/10-D12, Trimming
This version of the LSM 10A series offers a special output voltage trimming
feature which is fully compatible with competitive units. The output voltage
may be varied from 0.75 to 5 Volts using a single external trim up resistor connected from the Trim input to Output Common. If no trim resistor is attached
(Trim pin open), the output is 0.7525 Volts.
The trim may also be adjusted using an external reference voltage connected to the Trim input.
As with other trim adjustments, use a 1% metal film precision resistor with
low temperature coefficient (±100 ppm/°C or less) mounted close to the converter with short leads. Also be aware that the output accuracy is ±2% (typical)
therefore you may need to vary this resistance slightly to achieve your desired
output setting.
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MDC_LSM 10A D12 Models.D02 Page 7 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
The resistor trim up equation for the LSM-T/10-D12 is as follows:
RTRIMUP (Ω) =
10500
–1000
VO – 0.7525
Where VO is the desired output voltage.
The LSM-T/10-D12 fixed resistance values to set the output values are:
VOUT
(typ.)
0.7525
RTRIM
(kΩ)
Open
1.0
1.2
41.424 22.46
1.5
1.8
2
2.5
3.3
5.0
13.05
9.024
7.417
5.009
3.122
1.472
CAUTION: To retain proper regulation, do not exceed the 5 Volt output.
Voltage Trim
The LSM-T/10-D12 may also be trimmed using an external voltage applied
between the Trim input and Output Common. Be aware that the internal “load”
impedance looking into trim pin is approximately 5kΩ. Therefore, you may have to
compensate for this in the source resistance of your external voltage reference.
VTRIM = 0.7 –(0.0667 x (VO – 0.7525))
The LSM-T/10-D12 fixed trim voltages to set the output voltage are:
VTRIM
0.7525
1.0
LSM-T/10-D12 thermal protection occurs at +125°C and restart at approximately +115°C.
As you may deduce from the derating curves and observe in the efficiency
curves on the following pages, LSM D12 SMT's maintain virtually constant
efficiency from half to full load, and consequently deliver very impressive
temperature performance even if operating at full load.
Lastly, when LSM D12 SMT's are installed in system boards, they are
obviously subject to numerous factors and tolerances not taken into account
here. If you are attempting to extract the most current out of these units under
demanding temperature conditions, we advise you to monitor the outputinductor temperature to ensure it remains below +110°C at all times.
Start Up Considerations
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:
The equation for this voltage adjustment is:
VOUT
(typ.)
The highest temperatures in LSM D12 SMT's occur at their output inductor,
whose heat is generated primarily by I 2 R 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.
1.2
1.5
1.8
2
2.5
3.3
5.0
Open 0.68354 0.67
0.65
0.63
0.617
0.583
0.53
0.4166
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.
Output Reverse Conduction
Many DC/DCs 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.
4 – Longer distance to input voltage source and/or higher external input
source impedance.
LSM D12 SMT DC/DC converters do not suffer from Output Reverse Conduction. They employ proprietary gate drive circuitry that makes them immune to
applied output voltages.
8 – Output loads with excessive inductive reactance or constant current
characteristics.
Thermal Considerations and Thermal Protection
The typical output-current thermal-derating curves shown below enable
designers to determine how much current they can reliably derive from each
model of the LSM D12 SMT's under known ambient-temperature and air-flow
conditions. Similarly, the curves indicate how much air flow is required to reliably deliver a specific output current at known temperatures.
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.
If the input voltage is already at the low limit before power is applied, the
start up surge current may instantaneously reduce the voltage at the input
terminals to below the 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.
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MDC_LSM 10A D12 Models.D02 Page 8 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
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.
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.
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 some times and not others.
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.
Solutions
To improve start up, review the conditions above. One of the better solutions is
to place a moderate size capacitor very close to the input terminals. You may
need two parallel capacitors. A larger electrolytic or tantalum cap supplies the
surge current and a smaller parallel low-ESR ceramic cap gives low AC 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.
The capacitors will not help if the input source has poor regulation. A
converter which starts successfully at 3.3 Volts will turn off if the input voltage
decays to below the input voltage theshold, regardless of external capacitance.
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).
Finally, it is challenging to model some application circuits with absolute
fidelity. How low is the resistance of your ground plane? What is the inductance
(and distributed capacitance) of external wiring? Even a detailed mathematical
model may not get all aspects of your circuit. Therefore it is difficult to give cap
values which serve all applications. Some experimentation may be required.
Typical Performance Curves for LSM D12 SMT Series
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
6).6
.ATURAL#ONVECTION
LFM
LFM
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
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MDC_LSM 10A D12 Models.D02 Page 9 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Typical Performance Curves for LSM D12 SMT Series
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
.ATURAL#ONVECTION
LFM
LFM
6).6
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
6).6
.ATURAL#ONVECTION
LFM
LFM
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
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MDC_LSM 10A D12 Models.D02 Page 10 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Typical Performance Curves for LSM D12 SMT Series
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
6).6
.ATURAL#ONVECTION
LFM
LFM
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
.ATURAL#ONVECTION
LFM
LFM
6).6
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
www.murata-ps.com/support
MDC_LSM 10A D12 Models.D02 Page 11 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Typical Performance Curves for LSM D12 SMT Series
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
6).6
.ATURAL#ONVECTION
LFM
LFM
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
6).6
.ATURAL#ONVECTION
LFM
LFM
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
www.murata-ps.com/support
MDC_LSM 10A D12 Models.D02 Page 12 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Typical Performance Curves for LSM D12 SMT Series
,3-$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#
,3-$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
3-4MOUNTAIRFLOWDIRECTIONFROMPINTOPIN
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
.ATURAL#ONVECTION
LFM
LFM
6).6
6).6
n
!MBIENT4EMPERATUREo#
,OAD#URRENT!MPS
,3-4$
%FFICIENCYVS,INE6OLTAGEAND,OAD#URRENT —#6/546
,3-4$
-AXIMUM/UTPUT#URRENTVS!MBIENT4EMPERATURE
6/546TRANSVERSEAIRFLOW
/UTPUT#URRENT!MPS
%FFICIENCY
6).6
6).6
6).6
.ATURAL#ONVECTION
LFM
LFM
LFM
LFM
,OAD#URRENT!MPS
n
!MBIENT4EMPERATUREo#
www.murata-ps.com/support
MDC_LSM 10A D12 Models.D02 Page 13 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Typical Performance Curves for LSM D12 SMT Series
Start-Up from ON/OFF
(VIN = 12V, IOUT = 0.8V/10A, COUT = 22µF)
Start-Up from VIN
(VIN = 12V, IOUT = 0.8V/10A, COUT = 22µF)
VIN
5V/div
VIN
5V/div
VOUT
1V/div
VOUT
1V/div
10msec/div
10msec/div
Start-Up from VIN
(VIN = 12V, IOUT = 5V/10A, COUT = 22µF)
Start-Up from ON/OFF
(VIN = 12V, IOUT = 5V/10A, COUT = 22µF)
VIN
5V/div
VIN
5V/div
VOUT
2V/div
VOUT
2V/div
10msec/div
10msec/div
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MDC_LSM 10A D12 Models.D02 Page 14 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Typical Performance Curves for LSM D12 SMT Series
Output Hiccup
(LSM-5/10-D12 Shorted VOUT, VIN = 12V)
Input Reflected Ripple Current
(Input Filter = 220µF/12µH/33µF, VIN = 12V, IOUT = 5V/10A)
100mV/div
50mA/div
20msec/div
2µsec/div
Output Ripple and Noise
(VIN = 12V, VOUT = 5V/10A, COUT= 22µF)
20mV/div
Output Ripple and Noise
(VIN = 12V, VOUT = 0.8V/10A, COUT = 22µF)
20mV/div
2µsec/div
2µsec/div
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MDC_LSM 10A D12 Models.D02 Page 15 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Typical Performance Curves for LSM D12 SMT Series
Dynamic Load Response
(VIN = 12V, VOUT = 5V, 0 to 10A Step, COUT = 22µF)
200mV/div
Dynamic Load Response
(VIN = 12V, VOUT = 5V, 0 to 10A Step, CO = 22µF + 1000µF Oscon)
100mV/div
100µsec/div
100µsec/div
Dynamic Load Response
(VIN = 12V, VOUT = 0.8V, 5 to 10A Step, COUT= 22µF)
100mV/div
Dynamic Load Response
(VIN = 12V, VOUT = 5V, 5 to 10A Step, CO = 22µF + 1000µF Oscon)
100mV/div
100µsec/div
100µsec/div
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MDC_LSM 10A D12 Models.D02 Page 16 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Tape & Reel Surface Mount Package
Murata Power Solutions' LSM series DC/DC converters are the only highercurrent (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.
Virtually all SMT DC/DCs today are unprotected "open-frame" devices
assembled by their vendors with high-temperature solder (usually Sn96.5/Ag3.5
with a melting point +221°C) so that you may attach them to your board using
low-temperature solder (usually Sn63/Pb37 with a melting point of +183°C).
Conceptually straightforward, this "stepped" solder approach has its 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.
MPS is not exempted from the Laws of Physics. And we do not have magic
solders no one else has. We do have a simple and practical, straightforward
approach that works. We assemble our SMT DC/DC’s on a thermally-stable
plastic lead-frame (nylon 46, UL94V-0 flammability rated) using a high temperature lead-free solder. In addition, the LSM is transitioning to RoHS (Reduction
of Hazardous Substances) construction and SAC 305 RoHS-approved solder.
The lead-frame ensures coplanarity (to within 0.004 in.) of the unit's copper
leads. These leads are gold-plated with a nickel underplate. See Mechanical
Data for additional information.
The disposable heat shield, with a cutaway exposing the package leads,
provides thermal insulation to internal components during reflow and doubles
as the vacuum pick-up location. The insulation properties of the heat shield are
so effective that temperature differentials as high as 50°C develop inside-tooutside the shield. Oven temperature profiles with peaks of 250-260°C and
dwell times exceeding 2 minutes above 221°C are easily achieved. MPS's
new-generation SMT units are shipped in stackable, JEDEC-style plastic tray.
HEAT SHIELD OUTSIDE TEMPERATURE
250
Sn96.5/Ag3.5 Melting Point
Temperature (˚C)
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 D12 Models.D02 Page 17 of 18
LSM-10A D12 Models
Single Output Non-Isolated,
12Vin, 0.75-5Vout DC/DC Converters
Murata Power Solutions' new-generation LSM SMT DC/DC converters are
shipped in quantities of 150 modules per tape and reel.
1.102
(28)
0.158
(4)
2.205
(56)
1.370
(34.8)
CENTERED
PICK UP
LOCATION
NOTCH IN SHELL
INDICATES
PIN ONE.
2.063
(52.4)
1
1
1
CAUTION
PRESS TO REMOVE
THE HEAT SHIELD
AFTER THE SOLDER
PROCESS.
FEED
DIRECTION
TAPE
DIMENSIONS
IN INCHES (mm)
0.590
(14.97)
2.44
(62.0)
0.605
(15.36)
Figure 7. Tape Dimensions
13.0 (330.2)
7.38 (187.5)
0.51(13.0)
Figure 8. Reel Dimensions
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to: http://www.murata-ps.com/requirements/
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
notice.
© 2013 Murata Power Solutions, Inc.
www.murata-ps.com/support
MDC_LSM 10A D12 Models.D02 Page 18 of 18