LSM2-T-30-D12-C Datasheet, PDF (6/12 Pages) Murata Manufacturing Co., Ltd. – DOSA-SMT, 30A POL DC/DC Converters

LSM2-T/30-D12 Series
DOSA-SMT, 30A POL DC/DC Converters
Specification Notes continued:
(7) If Sense is connected remotely at the load, up to 0.5 Volts difference is allowed between the
Sense and +VOUT pins to compensate for ohmic voltage drop in the power lines. A larger volt-
age drop may cause the converter to exceed maximum power dissipation.
(8) Output noise may be further reduced by adding an external filter. See I/O Filtering and Noise Reduc-
tion.
(9) All models are fully operational and meet published specifications, including “cold start” at –40° C.
(10) Regulation specifications describe the deviation as the line input voltage or output load current
is varied from a nominal midpoint value to either extreme.
(11) Other input or output voltage ranges will be reviewed under scheduled quantity special order.
(12) Maximum continuous power requires that all on-board components not exceed +128°C pack-
age temperature.
(13) Do not exceed maximum power specifications when adjusting the output trim.
(14) The “R” option includes extra ground pads. These pads offer two important features. In addition
to carrying extra current, they also help dissipate additional heat. MPS strongly recommends
soldering the “R” pads to a thick ground plane with sizable area. The Operating Temperature
specification listed above assumes that these additional ground pads are connected to
a substantial ground plane below the converter ( at least several square inches).
(15) The maximum output capacitive loads depend on the the Equivalent Series Resistance (ESR)
of the external output capacitor. Larger caps will reduce output noise but may slow transient
response.
(16) Do not use Pre-bias startup and sequencing together. If you do not use the track function, leave
the seq/trk pin open.
(17) After short circuit shutdown, if the load is partially removed such that the load still exceeds the
overcurrent (OC) detection, the converter will remain in hiccup restart mode.
(18) Output current limiting is disabled at start up to avoid overcurrent shutdown while charging
external bypass capacitors.
Output Adjustments
The LSM2-T/30-D12 series includes a special output voltage trimming fea-
ture which is fully compatible with competitive units. The output voltage may
be varied using a single trim resistor from the Trim Input to Power Common.
Use a precision, low-tempco resistor (±100 ppm/^οC) mounted close to
the converter with short leads. Be aware that the voltage accuracy is ±1.5%
(typical) therefore adjust this resistance to achieve your desired output.
Resistor Trim Equation
1200
RTRIM (in Ohms) = --------------------- -100
VOUT – 0.8
The fixed trim resistors to set the output voltage are:
VOUT
0.8V.
1.0V.
1.2V.
Rtrim (Ohms) Open 5.90 KΩ 2.90 KΩ
VOUT
2.0V.
2.5V.
3.3V.
Rtrim (Ohms) 0.90 KΩ 605 Ω 380 Ω
1.5V.
1.614
KΩ
5.0V.
185.71
Ω
1.8V.
1.10 KΩ
Voltage Reference,
Figure 2. Voltage Trim Connections
Voltage Trim
The LSM2 Series may also be trimmed using an external low-noise voltage
applied between the Trim input and Output Common. Be aware that the inter-
nal “load” impedance looking into Trim pin is below 1000 Ohms and includes
factors from the output voltage. Therefore, use a low impedance source
resistance in your external voltage reference.
The fixed trim voltages to set the output voltage are:
VOUT (typ.)
0.80V. 1.0V.
1.2V.
1.5V.
Vtrim (Volts) Open 0.731V. 0.719V. 0.7V.
1.8V.
0.682V
Figure 1. Trim Resistor Connections
VOUT (typ.)
2.0 V.
2.5V.
3.3V.
5.0V.
Vtrim (Volts) 0.669V. 0.638V. 0.589V. 0.484V.
Soldering Guidelines
Vtrim = 0.7434 – [(((Vout – 0.7434) ÷ 1620) – 0.000035) x 100] where Vout
= desired voltage
Murata Power Solutions recommends the specifications below when installing these converters. These specifications vary depending on the solder type. Exceeding these specifica-
tions may cause damage to the product. Your production environment may differ therefore please thoroughly review these guidelines with your process engineers.
Reflow Solder Operations for surface-mount products (SMT)
For Sn/Ag/Cu based solders:
For Sn/Pb based solders:
Preheat Temperature
Less than 1 ºC. per second Preheat Temperature
Time over Liquidus
45 to 75 seconds
Time over Liquidus
Maximum Peak Temperature 260 ºC.
Maximum Peak Temperature
Cooling Rate
Less than 3 ºC. per second Cooling Rate
Less than 1 ºC. per second
60 to 75 seconds
235 ºC.
Less than 3 ºC. per second
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