LSN10A-D12 Datasheet, PDF (4/12 Pages) Murata Manufacturing Co., Ltd. – Single Output, Non-Isolated, 12VIN, 1-5VOUT, 10A, DC/DCs in SIP Packages

LSN-10A D12 Models
Single Output, Non-Isolated, 12VIN, 1-5VOUT, 10A, DC/DC's in SIP Packages
elements and should be selected for bulk capacitance, low ESR, and appro-
Remote Sense
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.
LSN D12 SIP Series DC/DC converters offer an output sense function on
pin 3. The sense function enables point-of-use regulation for overcoming
moderate IR drops in conductors and/or cabling. Since these are non-isolated
All external capacitors should have appropriate voltage ratings and be located devices whose inputs and outputs usually share the same ground plane,
as close to the converters as possible. Temperature variations for all relevant sense is provided only for the +Output.
parameters should be taken into consideration.
The remote sense line is part of the feedback control loop regulating the
The most effective combination of external I/O capacitors will be a function
DC/DC converter’s output. The sense line carries very little current and
of your line voltage and source impedance, as well as your particular load and consequently requires a minimal cross-sectional-area conductor. As such, it
layout conditions. Our Applications Engineers can recommend potential solu- is not a low-impedance point and must be treated with care in layout and
tions and discuss the possibility of our modifying a given device’s internal filter- cabling. Sense lines should be run adjacent to signals (preferably ground),
ing to meet your specific requirements. Contact our Applications Engineering
and in cable and/or discrete-wiring applications, twisted-pair or similar tech-
Group for additional details.
niques should be used. To prevent high frequency voltage differences between
Input Fusing
VOUT and Sense, we recommend installation of a 1000pF capacitor close to
the converter.
Most applications and or safety agencies require the installation of fuses
at the inputs of power conversion components. LSN D12 Series DC/DC
converters are not internally fused. Therefore, if input fusing is mandatory,
either a normal-blow or a slow-blow fuse with a value no greater than 9 Amps
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] b 10%VOUT
should be installed within the ungrounded input path to the converter.
Power derating (output current limiting) is based upon maximum output cur-
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.
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 LSN's specified rating. Therefore:
Safety Considerations
LSN D12 SIP'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).
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.
(VOUT at pins) x (IOUT) b rated output power
The internal 10.57resistor 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: Connect the +Sense pin (pin 3) to +Output (pin 4) at the DC/DC
converter pins, if the sense function is not used for remote regulation.
On/Off Control and Power-up Sequencing
Input Overvoltage and Reverse-Polarity Protection
LSN D12 SIP 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 (10.8 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.
The On/Off Control pin may be used for remote on/off operation. LSN D12 SIP
Series DC/DC's are designed so they are enabled when the control pin is
left open (internal pull-down to Common) and disabled when the control pin is
pulled high (+2.8V to +VIN), as shown in Figure 2 and 2a.
Dynamic control of the on/off function is best accomplished with a mechanical
relay or open-collector/open-drain drive circuit. The drive circuit should be
able to sink appropriate current when activated and withstand appropriate
voltage when deactivated.
+INPUT
4.12k7
ON/OFF
CONTROL
1.62k7
10k7
COMMON
Figure 2. Driving the On/Off Control Pin with an Open-Collector Drive Circuit
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