FLT007A0 Lineage Power, FLT007A0 Datasheet - Page 5

• Manufacturer Part Number: FLT007A0
• Manufacturer: Lineage Power

Specifications of FLT007A0

• Operating Temperature Min Deg. C: -40C
• Operating Temperature Max Deg. C: 85C
• Rad Hardened: No
• Lead Free Status / RoHS Status: Not Compliant

Data Sheet
March 26, 2008
Application Guidelines
Conducted noise on the input power lines can occur
as either differential-mode or common-mode noise
currents. Differential-mode noise is measured
between the two input lines, and is found mostly at
the low frequency end of the spectrum. This noise
shows up as noise at the fundamental switching
frequency and its
harmonics. Common-mode noise is measured
between the input lines and ground and is mostly
broadband noise above 10 MHz. The high-frequency
nature of common-mode noise is mostly due to the
high-speed switching transitions of power train
components.
Either or both types of noise may be covered in
a specification, as well as a combination of the two.
Differential-mode noise is best attenuated using a
filter composed of line-to-line capacitors (X caps) and
series inductance, provided by either a discrete
inductor or the leakage inductance of a common-
mode choke. In addition to the differential filtering
provided by the filter
module, it is recommended that an electrolytic
capacitor be located at the converter side of the filter
to provide additional attenuation of low-frequency
differential noise and to provide a low source
impedance for the converter, preventing input filter
oscillations and load transient
induced input voltage dips.
Open-frame DC/DC converter modules and the older
metal-cased DC/DC converter modules require
slightly different filtering arrangements. The
FLT007A0 series of modules are optimized for the
newer open-frame series of modules, but can also be
used with older metal-case modules. The main
differences in filtering recommendations between the
two types of modules are in common-mode filtering,
as explained below.
Filtering Open-Frame DC/DC
Converter Modules
For filtering open-frame DC/DC converter modules,
the recommended circuit is shown in Fig. 5. In
addition to the input electrolytic filter capacitor C1
(recommended value is a minimum of 100uF and
approximately 1uF/W at power levels above 100W),
common-mode filtering capacitors C2 and C3 should
be connected between the input and outputs as
shown. Suitable values for common-mode capacitors
C2 and C3 are in the range between 1000pF to 0.1μF
are usually indicated in the DC/DC converter data
sheet. These capacitors need to be rated for the
isolation voltage desired between the input and output
sides of the DC/DC converter module. The
recommended power layout of the modules showing
LINEAGE
POWER
75Vdc Input Voltage Maximum, 7A Output Current Maximum
FLT007A0/FLT007A0-SR Input Filter Modules
where the two common-mode capacitors are to be
placed is shown in Fig. 6.
Filtering Metal-Case DC/DC Converter
Modules
For metal-case DC/DC converter modules with a case
pin, a different filtering arrangement and layout is
recommended. Figure 7 shows the schematic
diagram of the recommended circuit. The main
difference with open-frame module is the use of an
isolated shield plane located underneath the module
which is connected through capacitors C2 through C5
to the input and output connections of the module.
The shield plane along with the case of the module
serves as a Faraday shield helping reduce EMI. The
corresponding layout for metal-case modules is
shown in Fig. 8.
Figure 5. Schematic diagram showing
recommended connection of the FLT007A0
filter module with open-frame DC/DC converter
modules.
Figure 6. Diagram showing recommended
layout of the FLT007A0 filter module with open-
frame DC/DC converter modules.
Input
VI(+)
VI(-)
V
V
IN
IN
CHASSIS
GROUND
+
−
CHASSIS GROUND
GND
V
V
FLT007A0
MODULE
IN
MODULE
IN
+
−
FILTER
V
V
O
O
+
−
C
1
C1
V
V
I
+
I
−
CONVERTER
VI(+)
CONVERTER
VI(-)
MODULE
DC/DC
DC/DC
C2
C
C3
C
2
3
V
V
O
O
VO(+)
VO(-)
+ PLANE
− PLANE
V
V
O
O
+
−
Load
5