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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

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.

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

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.

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 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.

LSM-EB Series

10 Amp DC/DC Power Converter Evaluation Boards

www.murata-ps.com

MDC_LSM_EB.B01 Page 2 of 5