LCM-120_13 Datasheet, PDF (1/7 Pages) Interpoint Corporation Company – LCM-120 Line Conditioning Module 28 Volt input – 120 watt

Crane Aerospace & Electronics Power Solutions
LCM-120 Line Conditioning Module
28 Volt input – 120 watt
Features
Powers dc-dc converters requiring 28 Vin
Input voltage 12 to 50 VDC
• Operating temperature -55° to +125°C
• Works through transients of
up to 80 V for up to 120 ms
• Inhibit function
• Synchronization function
• Undervoltage lockout
MODELS
VDC Output
LCM-120 24 to 36 VDC
description
The LCM-120™ line conditioning module is a non-isolated dc-dc
converter used to extend the input voltage range of Interpoint’s
dc-dc converters. The LCM-120 delivers up to 120 watts of
throughput power from a 12 to 50 volt dc source in one of three
modes:
• 12 to 24 volts input – internal boost converter
delivers 24 V
• 24 to 36 volts input – input is connected
directly to output
• 36 to 50 volts input – internal buck converter
delivers 36 V
Converter Design
The LCM-120 module is protected by internal current limit
circuitry which limits current according to input voltage. This
feature also allows safe charging of large external capacitors.
Because current is sensed between input common and output
common there is normally no external connection made between
these pins. (Note: If an external connection between input
and output common is desired, the resistance of this external
connection must be greater than 1 ohm.) The LCM module will
work through up to an 80 volt transient for up to 120 milliseconds
while holding the output at 36 VDC.
Features
Features include an under voltage lockout, an inhibit input, a
synchronization input and a power fail flag output. Under voltage
lockout prevents start-up for inputs less than 12 volts dc and will
shut down the converter for an input of less than 10 volts dc. The
inhibit input, when connected to input common, disables the
internal converter and opens the output power path while leaving
the power fail flag unaffected. Inhibit is normally left open or
pulled up with a resistor. The sync input allows synchronization of
the LCM-120 module’s internal clock to an external pulse source
with LSTTL level voltages and a 40% to 60% duty cycle. When
unused, the sync should be left unconnected. The power fail flag
output is a fully isolated NPN opto-coupler transistor rated to 18
volts dc. It will drive an external LSTTL load low if the LCM-120
module’s input voltage drops below 10 volts dc and will remain
active until the module output voltage also drops below 10 volts
dc.
Low V_in and Heavy Loads
When the LCM-120 module is operated at 12 volts in and 120
watts output, line loss can become a major concern. The module
will output 24 volts at 120 watts. Allowing for efficiency, the input
current will be 120 watts / 0.88 / 12 = 11.36 A. If the resistance in
the line from the power source to the LCM-120 is 0.05 ohms, the
line loss at 12 volts from the power source will be (0.05 • 11.36)
= 0.57 volts. The LCM-120 module will see 11.43 volts and will
not start up.
External Capacitance
Interpoint recommends a minimum output capacitance of 330 uF
and a total ESR of at least 0.25 ohms to ensure stability of the
LCM-120 module’s boost converter. For very low ESR capacitors,
an external series resistor (non-inductive) may be used to
obtain the minimum total ESR. The maximum recommended
capacitance is 1 F.
Crane Aerospace & Electronics
Power Solutions – Interpoint Products
10301 Willows Rd. NE, Redmond, WA 98052
+1.425.882.3100 • [e-mail]
www.craneae.com/interpoint
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LCM-120 Rev AA - 2013.06.14