GE Industrial Solutions LC-LW015-Series - Manual (Page 15)

Lineage Power 15
Data Sheet
March 27, 2008 18 Vdc to 36 Vdc or 36 Vdc to 75 Vdc Inputs, 10 W and 15 W
LC/LW010- and LC/LW015-Series Power Modules:
Design Considerations
Input Source Impedance
The power module should be connected to a low
ac-impedance input source. Highly inductive source
impedances can affect the stability of the power mod-
ule. If the source inductance exceeds 4 µH, a 33 µF
electrolytic capacitor (ESR < 0.7
Ω at 100 kHz)
mounted close to the power module helps ensure
stability of the unit.
Safety Considerations
For safety-agency approval of the system in which the
power module is used, the power module must be
installed in compliance with the spacing and separation
requirements of the end-use safety agency standard,
i.e., UL 1950, CSA 22.2 No. 950-95, EN60950, and
IEC950.
For the converter output to be considered meeting the
requirements of safety extra-low voltage (SELV), one of
the following must be true of the dc input:
n
All inputs are SELV and floating, with the output also
floating.
n
All inputs are SELV and grounded, with the output
also grounded.
n
Any non-SELV input must be provided with rein-
forced insulation from any other hazardous voltages,
including the ac mains, and must have a SELV reli-
ability test performed on it in combination with the
converters.
The power module has extra-low voltage (ELV) outputs
when all inputs are ELV.
The input to these units is to be provided with a maxi-
mum 5 A normal-blow fuse in the ungrounded lead.
Feature Descriptions
Output Overvoltage Clamp
The output overvoltage clamp consists of control cir-
cuitry, independent of the primary regulation loop, that
monitors the voltage on the output terminals. This con-
trol loop has a higher voltage set point than the primary
loop (see Feature Specifications table). In a fault condi-
tion, the overvoltage clamp ensures that the output
voltage does not exceed V
O, clamp, max . This provides a
redundant voltage-control that reduces the risk of
output overvoltage.
Current Limit
To provide protection in a fault (output overload) condi-
tion, the unit is equipped with internal current-limiting
circuitry and can endure current limiting for an unlim-
ited duration. At the point of current-limit inception, the
unit shifts from voltage control to current control. If the
output voltage is pulled very low during a severe fault,
the current-limit circuit can exhibit either foldback or
tailout characteristics (output-current decrease or
increase). The unit operates normally once the output
current is brought back into its specified range.
Remote On/Off (Optional)
Two remote on/off options are available. Positive logic,
device code suffix “4”, remote on/off turns the module
on during a logic-high voltage on the remote ON/OFF
pin, and off during a logic low. Negative logic, device
code suffix “1”, remote on/off turns the module off dur-
ing a logic high and on during a logic low.
To turn the power module on and off, the user must
supply a switch to control the voltage between the
on/off terminal and the V
I
(–) terminal (V
on/off
). The
switch may be an open collector or equivalent (see
Figure 38). A logic low is V
on/off
= –0.7 V to +1.2 V. The
maximum I
on/off
during a logic low is 1 mA. The switch
should maintain a logic-low voltage while sinking 1 mA.
During a logic high, the maximum V
on/off
generated by
the power module is 10 V. The maximum allowable
leakage current of the switch at V
on/off
= 10 V is 50 µA.
The module has internal capacitance to reduce noise
at the ON/OFF pin. Additional capacitance is not gen-
erally needed and may degrade the start-up character-
istics of the module.
8-758(C).a
Figure 38. Remote On/Off Implementation
+
I on/off
-
V on/off
REMOTE
ON/OFF
V I (+)
V I (-)