JFW100G1 Lineage Power, JFW100G1 Datasheet - Page 9

• Manufacturer Part Number: JFW100G1
• Manufacturer: Lineage Power

April 2008
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. For the test configuration in Figure 11, a 33 µF
electrolytic capacitor (ESR < 0.7 ¾ at 100 kHz)
mounted close to the power module helps ensure sta-
bility of the unit. For other highly inductive source
impedances, consult the factory for further application
guidelines.
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., UL1950, CSA C22.2 No. 950-95, and VDE 0805
(EN60950, IEC950).
If the input source is non-SELV (ELV or a hazardous
voltage greater than 60 Vdc and less than or equal to
75 Vdc), for the module’s output to be considered
meeting the requirements of safety extra-low voltage
(SELV), all of the following must be true:
n
n
n
n
Note: Do not ground either of the input pins of the
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 20 A normal-blow fuse in the ungrounded lead.
Lineage Power
The input source is to be provided with reinforced
insulation from any hazardous voltages, including the
ac mains.
One V
both the input and output pins are to be kept floating.
The input pins of the module are not operator acces-
sible.
Another SELV reliability test is conducted on the
whole system, as required by the safety agencies, on
the combination of supply source and the subject
module to verify that under a single fault, hazardous
voltages do not appear at the module’s output.
module without grounding one of the output pins.
This may allow a non-SELV voltage to appear
between the output pin and ground.
I
pin and one V
O
pin are to be grounded, or
dc-dc Converters; 36 to 75 Vdc Input; 2.5 Vdc Output; 25 W to 75 W
Feature Descriptions
Overcurrent Protection
To provide protection in a fault (output overload) condi-
tion, the unit is equipped with internal current-limiting
circuitry and optional delayed shutdown. At the point of
current-limit inception, the unit shifts from voltage con-
trol 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 will
operate normally once the output current is brought
back into its specified range. If the module has the
optional delayed current-limit shutdown, the unit will
operate normally once the output current is brought
back into its specified range, provided the overcurrent
condition is removed before the module shuts down.
The current-limit set point can be reduced by connect-
ing a resistor between the overcurrent trim (OCTRIM)
pin and SENSE(–) pin. The resistor value is derived by
the following equation:
Where:
R
I
I
Remote On/Off
There are two remote on/off signals, a primary refer-
enced signal and a secondary referenced signal. Both
signals must be asserted on for the module to deliver
output power. If either signal is asserted off, the module
will not deliver output power. Both signals have internal
pull-up circuits and are designed to interface with an
open collector pull-down device. Typically, one on/off
signal will be permanently enabled by hardwiring it to
its return while the other on/off signal is used exclu-
sively for control.
rated
trim
cl-adj
R
cl-adj
is the value of an external resistor between the
OCTRIM pin and SENSE(–) pin.
is the output current rating of the module.
(not the output current limit inception).
is the trimmed value of the output current-limit
set point.
=
⎛
⎝
11 I
--------------------------------------------------- -
1.15 I
trim
–
rated
1.15 I
–
I
trim
rated
⎞ kΩ
⎠
9