LSM-EB Datasheet, PDF (2/5 Pages) Murata Manufacturing Co., Ltd. – 10 Amp DC/DC Power Converter Evaluation Boards

LSM-EB Series
10 Amp DC/DC Power Converter Evaluation Boards
Specification Summary ~
DC/DC Converter type
DATEL LSM series ~
Input Voltage
3.3, 5 or 12 Volts (see Ordering Guide)
Output Voltage
0.8 to 5 Volts, (see Ordering Guide)
Output Current
10 Amps, max.
Minimum load
Zero (no minimum load)
Input and Output Terminals
banana jacks (4 locations)
0.166-inch (4.22mm) removable
Outline Dimensions
4.31" x 4.31" x 1.5" max. (including standoffs)
Height above board
0.41"
Standoffs €
Four removable, 1.0" length, 4-40 threaded
Fabrication
Multi-layer printed circuit board
Operating Temp. Range
(Ambient, natural convection)
–40 to +65/+71°C 
~See DATEL's LSM series data sheet for full information on the DC/DC converter.
 Maximum operating temperature ranges are dependent on model type. See the LSM series
converter data sheet. Temperature range may be extended with forced cooling.
€ The standoffs are not connected to the board ground plane. Use a discrete connection if you
wish to ground the standoffs.
Diagnostic Test Points
Four pins are provided for a combination of measurements. Pins 1 and 2
sense the voltage immediately at the DC/DC inputs. Pins 3 and 4 display the
output voltage. Connect these pins either to an oscilloscope or voltmeter.
If preferred, the input inductor may be bypassed by shorting J1 to Pin 1.
Input Current Measurement
A current sense resistor (not supplied) may be conveniently installed across
the input inductor from J1 to Pin 1 after removing inductor L1 with a
surface mount hot air desoldering tool. Suggested resistor values are 2 to 5
milliohms. These values will not degrade operation of the DC/DC converter
yet will develop sufficient voltage at full power for measurement by a digital
voltmeter or oscilloscope.
Note that the 'scope must be connected in differential mode. If preferred,
a sense resistor can also be installed in series with either ground jack
without having to remove L1. A sense resistor of several milliohms may be
conveniently fabricated with several inches of 12 or 14 gauge wire.
Digital On/Off Control
Component Locations
The board is laid out with filter capacitors and the inductor on the input and
a filter capacitor on the output. These represent typical values that you would
normally use in your application therefore, performance should be similar.
Also, the values comply with those recommended in the LSM data sheet.
The two trim resistor locations (R3 and R4) are left open for the user to install
suitable trim resistors, either as axial lead resistors or "0805" surface mount
resistors. White silkscreening on the board identifies all components.
Usage Guidelines
The top section (SW1-A) of the 3-pole DIP switch enables the power output
of the converter. You may either do this manually with the rocker switch or
connect an external logic gate to the pole nearest the output terminals on
the back side of the board. Such an external gate should be referenced to the
converter's power ground and use 5V TTL/LS logic.
A small reed relay or an open collector NPN transistor or FET may also be
used to control the DC/DC with the collector tied to the same control terminal
pole on the DIP switch. The converter's on/off control includes an internal
pullup resistor to +5V. The pullup is 5 to 14 kilohms, depending on model.
Leave the on-board DIP switch open if you use any of these external controls.
Use short leads if you install an external control.
Refer to the LSM series data sheet for full details on the following topics.
Input/Output Connections
Holding the module upright, input power is applied to the left set of banana
jacks. Output power is extracted from the right banana jacks. Please note
that both ground terminals on the bottom are connected together internally.
To retain high system performance, be sure to use the proper gauge wiring
(12 gauge or larger is recommended). The hex standoffs are not connected
to the ground plane.
Use as short wiring as possible. For longer power wiring, to prevent noise
radiation, consider either twisting the leads and/or enclosing the leads in a
grounded copper shield.
Input Pi Filter
A classic Pi filter is provided on the converter's input. While this filter
is not required if you can assure that the input voltage at the DC/DC
terminals remains within the input voltage range at all times and is reason-
ably low noise, many applications will see improved performance if the filter
is employed. The filter is also useful for switching output loads and for
evaluation of input ripple current. The inductor and associated capacitors are
selected to prevent saturation and excessive power dissipation at the full 10
Amp output current while avoiding inductive spike damage to the DC/DC. The
capacitors are chosen for low ESR.
If the on/off control is left open, the converter will operate normally. Always
make sure the DC/DC is powered up before activating the on/off control.
Trim Circuits
The bottom two sections of the 3-pole DIP switch connects the converter's
single trim input to two external resistor positions immediately to the right of
the switch body. See the schematic diagram. The upper resistor corresponds
to the leg connecting to the +VOUT terminal and the bottom resistor connects
to –VOUT. The switches allow you to temporarily disconnect the trim resistors
to evaluate their effects.
You may either install discrete resistors in these two through-hole or surface
mount locations or you may wire a closely-mounted 20 kilohm potentiometer
between the board pads. Use short leads to prevent noise pickup and
instability. Study the LSM data sheet for the required resistor values.
Thermal Considerations
The DC/DC converter, when mounted on the evaluation board, is rated up
to approximately +65 degrees Centrigrade operation (depending on model)
using natural convection at low or moderate altitude. The converter is pro-
tected by thermal shutdown if overcurrent, higher altitude and/or overtemper-
ature operation is attempted. Some heat is extracted through the mounting
pads. Higher temperature operation is available with forced cooling. Carefully
study the derating curves on the LSM data sheet.
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