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LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Typical Unit
FEATURES
Step-down buck regulators for new distributed 12V power architectures 12V input (10-14V range) 0.75/1/1.2/1.5/1.8/2/2.5/3.3/5VOUT @16A Non-isolated, fixed-frequency, synchronous-rectifier topology Tape and reel SMT package 1.25% setpoint accuracy Efficiencies to 96% @ 16 Amps Noise as low as 50mVp-p Stable no-load operation Remote on/off control Sense pin and output voltage trim No derating to +65C with 200 lfm Designed to meet UL/IEC/EN60950-1 safety EMC compliant
PRODUCT OVERVIEW
LSM Series D12 SMTs (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 non-isolated, step-down buck regulators. LSM D12 DC/DC's accept a 12V input (10V to 14V input range) and convert it, with the highest efficiency in the smallest space, to a 0.75, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3 or 5 Volt output fully rated at 16 Amps. LSM D12's are ideal point-of-use/load power processors. They typically require no external components. Their surface-mount packages occupy a mere 1.3" x 0.53" (33.0 x 13.5mm), and are only 0.34 inches (8.6mm) high. The LSM's best-in-class power density is achieved with a fully synchronous, fixedfrequency, buck topology that also delivers: high efficiency (95% for 5VOUT models), low noise (50mVp-p typ.), tight line/load regulation (0.1%/0.25% max.), quick step response (100sec), stable no-load operation, and no output reverse conduction. The fully functional LSM's feature output overcurrent detection, continuous short-circuit protection, over-temperature protection, a remote on/off control pin (pull low to disable), an output-voltage trim function, and a sense pin. High efficiency enables the LSM D12's to deliver rated output currents of 16 Amps at ambient temperatures to +65C with 100 lfm air flow. If your new system boards call for multiple supply voltages, check out the economics of on-board 12V distributed power. If you don't need to pay for multiple isolation barriers, Murata Power Solutions' non-isolated LSM D12 SMTs will save you money.
+INPUT (2)
+OUTPUT (4)
+SENSE (6) COMMON (3) CURRENT SENSE VCC ON/OFF CONTROL (1) PWM CONTROLLER REFERENCE & ERROR AMP VOUT TRIM (5) COMMON (3)
Typical topology is shown
Figure 1. Simplified Schematic
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MDC_LSM 16A D12 Models.A05 Page 1 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Performance Specifications and Ordering Guide
ORDERING GUIDE Output VOUT (Volts)
0.75 1 1.2 1.5 1.8 2 2.5 3.3 5 0.75-5
Input Regulation (Max.) Line
0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1%
Efficiency (Full Load) IIN (mA/A)
35/1.26 35/1.57 40/1.84 50/2.26 55/2.67 55/2.93 60/3.62 70/4.68 85/7.06 85/7.02
Models
LSM-0.75/16-D12 LSM-1/16-D12 LSM-1.2/16-D12 LSM-1.5/16-D12 LSM-1.8/16-D12 LSM-2/16-D12 LSM-2.5/16-D12 LSM-3.3/16-D12 LSM-5/16-D12 LSM-T/16-D12
IOUT (Amps)
16 16 16 16 16 16 16 16 16 16
R/N (mVp-p) Typ.
50 50 50 50 50 50 50 50 75 50
Max.
75 75 75 75 75 75 75 75 100 75
Load
0.375% 0.25% 0.25% 0.25% 0.25% 0.25% 0.25% 0.25% 0.25% 0.25%
VIN Nom. (Volts)
12 12 12 12 12 12 12 12 12 12
Range (Volts)
10-14 10-14 10-14 10-14 10-14 10-14 10-14 10-14 10-14 10-14
VIN = nom. Min.
83% 83% 85% 86.5% 88% 89% 90% 92% 92.5% 93%
VIN = min Typ.
86% 86% 88% 89.5% 91% 91.5% 91.5% 94.5% 95.5% 95.5%
Typ.
85% 85% 87% 88.5% 90% 91% 92% 94% 94.5% 95%
Package (Case, Pinout)
C45, P63 C45, P63 C45, P63 C45, P63 C45, P63 C45, P63 C45, P63 C45, P63 C45, P63 C45, P63
Typical at TA = +25C under nominal line voltage and full-load conditions, 200 lfm air flow for extended operation, unless otherwise noted. All models are tested and specified with external 22F 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. Ripple/Noise (R/N) is tested/specified over a 20MHz bandwidth and may be reduced with external filtering. See I/O Filtering and Noise Reduction for details. Part Number Structure
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. RoHS6 compliance does not claim EU RoHS exemption 7b-lead in solder.
Mechanical Specifications
1.30 (33.02)
L SM - 1.8 / 16 - D12 - C
Output Configuration: L = Unipolar Low Voltage Non-Isolated SMT Nominal Output Voltage: 0.75, 1, 1.2, 1.5, 1.8, 2, 2.5, 3.3 or 5 Volts
Note: Not all model number combinations are available. Contact MPS.
1.36 (34.54)
Dimensions are in inches (mm shown for ref. only).
Third Angle Projection
RoHS6 hazardous substance compliant*
Input Voltage Range: D12 = 10 to 14 Volts (12V nominal) Maximum Rated Output Current in Amps
* Contact Murata Power Solutions for availability.
0.34 (8.64)
SMT COPPER LEADS COPLANAR 0.004
0.570 (14.48) 3 EQ. SP. @ 0.190 (4.83)
0.085 (2.16)
Tolerances (unless otherwise specified): .XX 0.02 (0.5) .XXX 0.010 (0.25) Angles 2 Components are shown for reference only.
0.310 (7.87)
Case C45
3
0.55 (13.97)
4
5
6 1
0.062 (1.57) TYP.
2
0.53 0.48 (12.19) (13.46)
0.010 (0.254)
0.570 (14.48) 3 E Q . S P. @ 0.190 (4.83)
0.60 (15.24)
0.112 (2.84) TYP.
NOTCH IN SHELL INDICATES PIN ONE
0.05 (1.27)
BOTTOM VIEW
0.075 (1.91) 0.048 (1.22)
0.310 (7.87)
0.375 (9.53)
0.052 (1.32)
1.177 (29.90)
0.570 (14.48) 3 EQ. SP. @ 0.190 (4.83)
3 2
4
5
6 1
0.297 (7.54)
0.310 (7.87)
0.062 (1.57)
0.112 T Y P. (2.84) 0.049 (1.24)
0.047 (1.19) 0.052 (1.32)
CAUTION PRESS TO REMOVE THE HEAT SHIELD AFTER THE SOLDER PROCESS NOTCH IN SHELL INDICATES PIN ONE
0.405 (10.29)
1
6
5
4
3 2
0.430 (10.92)
BOTTOM VIEW
LSM WITH REMOVABLE HEAT SHIELD FOR HIGH TEMPERATURE SOLDER
RECOMMENDED PAD LAYOUT Recommended Pad Size: 0.15 x 0.10 (3.81 x 2.54)
I/O Connections Pin Function P63 1 On/Off Control 2 +Input 3 Common 4 +Output 5 VOUT Trim 6 +Sense
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MDC_LSM 16A D12 Models.A05 Page 2 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Performance/Functional Specifications
Input Typical @ TA = +25C under nominal line voltage and full-load conditions unless noted. All models are tested and specified with external 22F 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. See Technical Notes and Performance Curves for details. The On/Off Control (pin 1) is designed to be driven with open-collector logic (referenced to Common, pin 3) or a switch to ground. 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 = +25C, full power, natural convection, +67C pcb temperature. Input Ripple Current is tested/specified over a 5Hz-20MHz bandwidth with an external 2 x 100F input capacitor and a simulated source impedance of 1000F and 1H. See I/O Filtering, Input Ripple Current and Output Noise for details.
Input Voltage Range Startup Voltage
10-14 Volts (12V nominal) 8.5-9.2 Volts (model dependent)
Input Current: Normal Operating Conditions See Ordering Guide Inrush Transient 0.08A2 sec Standby/Off Mode 1.5mA Output Short-Circuit Condition 12-40mA average (model dependent) Input Reflected Ripple Current 20-50mAp-p, model dependent Input Filter Type Capacitive Overvoltage Protection None Reverse-Polarity Protection None Undervoltage Shutdown 7.5-8 Volts (model dependent) On/Off Control On = open lead Off = -0.3V to +0.2V (3A max.)
Output
Absolute Maximum Ratings
Input Voltage: Continuous or transient On/Off Control (Pin 1) Input Reverse-Polarity Protection Output Overvoltage Protection Output Current
15 Volts +6V None None Current limited. Devices can withstand sustained output short circuits without damage. -55 to +125C See Reflow Solder Profile
VOUT Accuracy (50% load) Minimum Loading Maximum Capacitive Load VOUT Trim Range Ripple/Noise (20MHz BW)
1.25% No load 1000F (low ESR, OSCON) 10% See Ordering Guide Total Accuracy 3% over line/load/temperature Efficiency See Ordering Guide Overcurrent Detection and Short-Circuit Protection: Current-Limiting Detection Point 21-33 Amps (model dependent) Short-Circuit Detection Point 98% of VOUT set SC Protection Technique Hiccup with auto recovery Short-Circuit Current 125-420mA average (model dependent)
Dynamic Characteristics
Storage Temperature Lead Temperature
These are stress ratings. Exposure of devices to greater than any of these conditions may adversely affect long-term reliability. Proper operation under conditions other than those listed in the Performance/Functional Specifications Table is not implied.
Technical Notes
Transient Response (50% load step) Start-Up Time: VIN to VOUT and On/Off to VOUT Switching Frequency Calculated MTBF LSM-1.2/16-D12 LSM-1.5/16-D12 LSM-1.8/16-D12 LSM-2.5/16-D12 LSM-3.3/16-D12 LSM-5/16-D12 Operating Temperature: (Ambient) Thermal Shutdown
30-135sec to 2% of final value (model dependent) 60msec for VOUT = 1V and 0.75V 40msec for VOUT = 1.2V to 5V 260kHz 10%
Environmental
I/O Filtering and Noise Reduction All models in the LSM D12 Series are tested and specified with external 22F 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 highquality, high-performance internal I/O caps, and will operate within spec in most applications with no additional external components. In particular, the LSM D12s input capacitors are specified for low ESR and are fully rated to handle the units' input ripple currents. Similarly, the internal output capacitors are specified for low ESR and full-range frequency response. As shown in the Performance Curves, removal of the external 22F 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/DCs requires that the dc input voltage source have low ac impedance at the frequencies of interest. Highly inductive source impedances can greatly affect system stability. Your specific system configuration may necessitate additional considerations.
9,160,138 hours 8,674,318 hours 8,334,117 hours 8,534,580 hours 7,817,255 hours 7,756,061 hours -40 to +85C (with Derating) See Derating Curves +115C (110 to 125C)
Physical
Dimensions Lead Dimensions/Material
Weight Flamability Rating Safety
1.3" x 0.53" x 0.34" (33.03 x 13.46 x 8.64) 0.112" x 0.062" (2.84 x 1.57mm) rectangular copper alloy with gold plate over nickel underplate 0.28 ounces (7.8g) UL94V-0 Designed to meetUL/cUL/IEC/EN 60950-1, CSA-C22.2 No. 234
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MDC_LSM 16A D12 Models.A05 Page 3 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Safety Considerations LSM D12 SMT's are non-isolated DC/DC converters. In general, all DC/DC's must be installed, including considerations for I/O voltages and spacing/separation requirements, in compliance with relevant safety-agency specifications (usually UL/IEC/EN60950-1). In particular, for a non-isolated converter's output voltage to meet SELV (safety extra low voltage) requirements, its input must be SELV compliant. If the output needs to be ELV (extra low voltage), the input must be ELV.
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.
Input Overvoltage and Reverse-Polarity Protection LSM D12 SMT Series DC/DC's do not incorporate either input overvoltage or input reverse-polarity protection. Input voltages in excess of the specified absolute maximum ratings and input polarity reversals of longer than "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 (10 Volts) and the fully loaded output voltage enters and remains within its specified accuracy band. Actual measured times will vary with input source impedance, external input capacitance, and the slew rate and final value of the input voltage as it appears to the converter. The On/Off to 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 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 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. 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: (VOUT at pins) x (IOUT) rated output power
+SENSE +OUTPUT
6 4
COPPER STRIP
C1
C2
SCOPE
RLOAD
COMMON
3 COPPER STRIP
C1 = NA C2 = 22F TANTALUM LOAD 2-3 INCHES (51-76mm) FROM MODULE
Figure 3. Measuring Input Ripple Current
All external capacitors should have appropriate voltage ratings and be located as close to the converters as possible. Temperature variations for all relevant parameters should be taken into consideration. The most effective combination of external I/O capacitors will be a 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. The LSM D12 Series are not internally fused. Therefore, if input fusing is mandatory, either a normal-blow or a fast-blow fuse with a value no greater than twice the maximum input current should be installed within the ungrounded input path to the converter. As a rule of thumb however, we recommend to use a normal-blow or slow-blow fuse with a typical value of about twice the maximum input current, calculated at low line with the converters minimum efficiency.
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MDC_LSM 16A D12 Models.A05 Page 4 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
The internal 10.5 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 current source to VIN (+Input). Leaving the input of the on/off circuit closed during power-up will have the output of the DC/DC converter disabled. When the input to the external open collector is pulled high, the DC/DC converter's output will be enabled. Output Overvoltage Protection LSM D12 SMT Series DC/DC converters do not incorporate output overvoltage protection. In the extremely rare situation in which the device's feedback loop is broken, the output voltage may run to excessively high levels (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. If the output current exceeds it maximum rating by typically 70% (27 Amps) or if the output voltage drops to less than 98% of it original value, the LSM D12's internal overcurrent-detection circuitry immediately turns off the 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 LSM D12 SMT Series are 10%. Trimming is accomplished with either a trimpot or a single fixed resistor. The trimpot should be connected between +Output and Common with its wiper connected to the Trim pin as shown in Figure 6 below.
Figure 4. On/Off Control Using An External Open Collector Driver
Dynamic control of the on/off function is best accomplished with a mechanical relay or open-collector/open-drain drive circuit (optically isolated if appropriate). The drive circuit should be able to sink appropriate current when activated and withstand appropriate voltage when deactivated. Applying an external voltage to the On/Off Control pin when no input power is applied to the converter can cause permanent damage to the converter. The on/off control function, however, is designed such that the converter can be disabled (control pin pulled low) while input voltage is ramping up and then "released" once the input has stabilized (see also power-up sequencing). Power-up sequencing If a controlled start-up of one or more LSM D12 Series DC/DC converters is required, or if several output voltages need to be powered-up in a given sequence, the On/Off control pin can be driven with an external open collector device as per Figure 5.
Figure 6. Trim Connections Using a Trimpot
A trimpot can be used to determine the value of a single fixed resistor which can then be connected, as shown in Figure 7, between the Trim pin and +Output to trim down the output voltage, or between the Trim pin and Common to trim up the output voltage. Fixed resistors should have absolute TCR's less than 100ppm/C to ensure stability.
Figure 5. Driving The External Power-Up Open Collector
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MDC_LSM 16A D12 Models.A05 Page 5 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
"T" Model LSM-T/16-D12 This version of the LSM 16A 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. The resistor trim up equation for the LSM-T/16-D12 is as follows:
RT UP ( ) = 10500 VO - 0.7525 - 1000
+OUTPUT +INPUT TRIM COMMON COMMON Trim Up Trim Down LOAD
Figure 7. Trim Connections Using Fixed Resistors
The equations below can be starting points for selecting specific trim-resistor values. Recall, untrimmed devices are guaranteed to be 1.25% accurate. Adjustment beyond the specified 10% 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
Where VO is the desired output voltage.
5.509 VO - VO NOM
RT DOWN (k ) =
7.87(VO - 0.7) VO NOM - VO
The LSM-T/16-D12 fixed resistance values to set the output values are:
-X
-X
RT UP (k ) =
VO RT (k)
0.7525V Open
1.0V
1.2V
1.5V
1.8V
2.5V
3.3V
5.0V
Where: VO = Desired Output Voltage VO NOM = Nominal Output Voltage LSM-0.75/16-D12: LSM-1/16-D12: LSM-1.2/16-D12: LSM-1.5/16-D12: LSM-1.8/16-D12: LSM-2/16-D12: LSM-2.5/16-D12: LSM-3.3/16-D12: LSM-5/16-D12: X = 0.909 X = 11.5 X = 19.1 X = 27.4 X = 16.9 X = 21.5 X = 18.2 X = 13.7 X = 9.09
41.424 22.46 13.05 9.024 5.009 3.122 1.472
CAUTION: To retain proper regulation, do not exceed the 5 Volt output. Voltage Trim The LSM-T/16-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 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: VTRIM = 0.7 - (0.0667 x (VO - 0.7525))
Note: Resistor values are in k. Accuracy of adjustment is subject to tolerances of resistors and factory-adjusted, initial output accuracy. VO = desired output voltage. VONOM = nominal output voltage.
The LSM-T/16-D12 fixed trim voltages to set the output voltage are: VO VT (V) 0.7525V Open 1.0V 1.2V 1.5V 0.650 1.8V 0.630 2.5V 0.583 3.3V 5.0V
0.6835 0.670
0.530 0.4166
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MDC_LSM 16A D12 Models.A05 Page 6 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
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. 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. 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 SMTs 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. The highest temperatures in LSM D12 SMTs 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 +110C under the assorted conditions of air flow and air temperature. Once the temperature exceeds +115C (approx.), the thermal protection will disable the converter. Automatic restart occurs after the temperature has dropped below +110C. 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 +110C at all times.
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MDC_LSM 16A D12 Models.A05 Page 7 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Typical Performance Curves for LSM D12 SMT Series
UQQ-5/17-Q12P Efficiency vs. Line Voltage and Load Current @ 25C 92 90 88 86 Efficiency (%) 84 82
VIN = 10V
80
VIN = 12V
78
VIN = 14V
76 74 1 2 3 4 5 6 7 8 Load Current (Amps)
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MDC_LSM 16A D12 Models.A05 Page 8 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Typical Performance Curves for LSM D12 SMT Series
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MDC_LSM 16A D12 Models.A05 Page 9 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Typical Performance Curves for LSM D12 SMT Series
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MDC_LSM 16A D12 Models.A05 Page 10 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
Tape & Reel Surface Mount Package Murata Power Solutions' LSM series DC/DC converters are the only highercurrent (16A) SMT DC/DCs 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 of +221C) so that you may attach them to your board using low-temperature solder (usually Sn63/Pb37 with a melting point of +183C). 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 215-216C? 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. Nevertheless, we have a simple and practical, straightforward approach that works. We assemble our LSM SMT DC/DCs using a high-temperature (+216C), lead-free alloy (Sn96.2%, Ag2.5%, Cu0.8%, Sb0.5%). The LSM design ensures co-planarity to within 0.004 inches (100m) 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 (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 temperature differentials as high as 50C develop inside-to-outside the shield. Oven temperature profiles with peaks of 250-260C and dwell times exceeding 2 minutes above 221C (the melting point of Sn96.5/Ag3.5) are easily achieved.
250 221
Sn96.5/Ag3.5 Melting Point
HEAT SHIELD OUTSIDE TEMPERATURE
Temperature (C)
200 183 150
Sn63/Pb37 Melting Point
PCB TEMPERATURE INSIDE THE HEAT SHIELD
100
50 0 50 100 150 200 250 300 350 400
Time (Seconds)
Figure 6. Reflow Solder Profile
www.murata-ps.com
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
MDC_LSM 16A D12 Models.A05 Page 11 of 12
LSM-16A D12 Models
Non-Isolated, 13-80W SMT DC/DC Converters
DATEL's new-generation LSM SMT DC/DC converters are shipped in quantities of 150 modules per tape and reel.
0.158 (4) 1.102 (28)
CENTERED PICK UP LOCATION
1.370 (34.8)
2.205 (56)
2.063 (52.4)
1 1 1
NOTCH IN SHELL INDICATES PIN ONE.
CAUTION PRESS TO REMOVE THE HEAT SHIELD AFTER THE SOLDER PROCESS.
FEED 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: Canada: UK: France: Germany: Japan: China: Singapore:
Mansfield (MA), Tel: (508) 339-3000, email: sales@murata-ps.com Toronto, Tel: (866) 740-1232, email: toronto@murata-ps.com Milton Keynes, Tel: +44 (0)1908 615232, email: mk@murata-ps.com Montigny Le Bretonneux, Tel: +33 (0)1 34 60 01 01, email: france@murata-ps.com Munchen, Tel: +49 (0)89-544334-0, email: munich@murata-ps.com Tokyo, Tel: 3-3779-1031, email: sales_tokyo@murata-ps.com Osaka, Tel: 6-6354-2025, email: sales_osaka@murata-ps.com Shanghai, Tel: +86 215 027 3678, email: shanghai@murata-ps.com Guangzhou, Tel: +86 208 221 8066, email: guangzhou@murata-ps.com Parkway Centre, Tel: +65 6348 9096, email: singapore@murata-ps.com
Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
Murata Power Solutions, Inc. 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 and 14001 REGISTERED
03/25/09
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. (c) 2009 Murata Power Solutions, Inc.
www.murata-ps.com
MDC_LSM 16A D12 Models.A05 Page 12 of 12

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