LSN2-T Datasheet, PDF (4/17 Pages) Murata Manufacturing Co., Ltd. – DOSA-SIP, 30A POL DC/DC Converters

LSN2-T/30-D12 Series
DOSA-SIP, 30A POL DC/DC Converters
Performance/Functional Specification Notes:
(1) Specifications are typical at +25°C, Vin = nominal (+12V), Vout = nominal (+5V), full
load, external caps and natural convection unless otherwise indicated.
All models are tested and specified with external 0.01µF, 0.1µF, and 10µF (all paral-
leled) ceramic/tantalum output capacitors and a 22µF external input capacitor. All
capacitors are low ESR types. 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.
(2) Input Back Ripple Current is tested and specified over a 5Hz to 20MHz bandwidth.
Input filtering is Cin = 2 x 100µF tantalum, Cbus = 1000µF electrolytic, Lbus = 1µH.
(3) Note that Maximum Power Derating curves indicate an average current at nominal
input voltage. At higher temperatures and/or lower airflow, the DC/DC converter will
tolerate brief full current outputs if the total RMS current over time does not exceed the
Derating curve.
(4) Mean Time Before Failure is calculated using the Telcordia (Belcore) SR-332
Method 1, Case 3, ground fixed conditions, TPCBOARD = +25°C, full output load,
natural air convection.
(5) The On/Off Control may be driven with external logic or by applying appropriate exter-
nal voltages which are referenced to –Input Common. The On/Off Control Input should
use either an open collector/open drain transistor or logic gate.
(6) Short circuit shutdown begins when the output voltage degrades approximately 2%
from the selected setting.
(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 voltage drop may cause the converter to exceed maximum power dissipation.
Connect sense to +Vout at the converter if sense is not connected to a remote load.
(8) Output noise may be further reduced by adding an external filter. See I/O Filtering and
Noise Reduction.
(9) All models are fully operational and meet published specifications, including “cold start”
at –40°C. At full power, the package temperature of all on-board components must not
exceed +128°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 PC board temperature is measured with the sensor in the center.
(13)Do not exceed maximum power specifications when adjusting the output trim.
(14)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.
(15)Static Discharge CAUTION: The Power Good output connects directly to the PWM
controller. Be sure to use proper grounding techniques to avoid damaging the converter.
Power Good is not valid when using Sequence/Tracking.
(16)The maximum output capacitive loads depend on the the Equivalent Series Resistance
(ESR) of theexternal output capacitor. Larger caps will reduce output noise but may
slow transient response or degrade dynamic performance. Use only as much output fil-
tering as needed and no more. Thoroughly test your system under full load, especially
with low-ESR ceramic capacitors.
(17) Do not use Pre-bias startup and sequencing together. See the Technical Notes below.
TECHNICAL NOTES
I/O Filtering and Noise Reduction
All models in the LSN2-T/30-D12 Series are tested and specified with external
0.01µF, 0.1µF, and 10µF (all paralleled) ceramic/tantalum output capaci-
tors and a 22µF tantalum input capacitor. These capacitors are necessary to
accommodate our test equipment and may not be required to achieve desired
performance in your application. The LSN2-T/30-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 LSN2-T/30-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.
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 appropri-
ate 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.
TO
OSCILLOSCOPE
+
VIN
–
LBUS
CBUS
CURRENT
PROBE ₂
CIN
3
CIN = 2 x 100µF, ESR < 700mΩ @ 100kHz
CBUS = 1000µF, ESR < 100mΩ @ 100kHz
LBUS = 1µH
+INPUT
COMMON
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 fre-
quency response. Any scope measurements of PARD should be made directly
at the DC/DC output pins with scope probe ground less than 0.5" in length.
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.
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