DS_E48SP12020NRFB_05232011
7
Safety Considerations
The power module must be installed in compliance with
the spacing and separation requirements of the
end-user’s safety agency standard, i.e., UL60950-1,
CAN/CSA-C22.2, No. 60950-1 and EN60950-1+A11 and
IEC60950-1, if the system in which the power module is
to be used must meet safety agency requirements.
Basic insulation based on 75 Vdc input is provided
between the input and output of the module for the
purpose of applying insulation requirements when the
input to this DC-to-DC converter is identified as TNV-2
or SELV. An additional evaluation is needed if the
source is other than TNV-2 or SELV.
When the input source is SELV circuit, the power module
meets SELV (safety extra-low voltage) requirements. If
the input source is a hazardous voltage which is greater
than 60 Vdc and less than or equal to 75 Vdc, for the
module’s output to meet SELV requirements, all of the
following must be met:
The input source must be insulated from the ac
mains by reinforced or double insulation.
The input terminals of the module are not operator
accessible.
If the metal baseplate / heatspreader is grounded
the output must be also grounded.
A SELV reliability test is conducted on the system
where the module is used, in combination with the
module, to ensure that under a single fault,
hazardous voltage does not appear at the module’s
output.
When installed into a Class II equipment (without
grounding), spacing consideration should be given to
the end-use installation, as the spacing between the
module and mounting surface have not been evaluated.
The power module has extra-low voltage (ELV) outputs
when all inputs are ELV.
This power module is not internally fused. To achieve
optimum safety and system protection, an input line fuse
is highly recommended. The safety agencies require a
Fast-acting fuse with 30A maximum rating to be
installed in the ungrounded lead. A lower rated fuse can
be used based on the maximum inrush transient energy
and maximum input current.
Soldering and Cleaning Considerations
Post solder cleaning is usually the final board assembly
process before the board or system undergoes electrical
testing. Inadequate cleaning and/or drying may lower the
reliability of a power module and severely affect the
finished circuit board assembly test. Adequate cleaning
and/or drying is especially important for un-encapsulated
and/or open frame type power modules. For assistance
on appropriate soldering and cleaning procedures,
please contact Delta’s technical support team.
DESIGN CONSIDERATIONS
Input Source Impedance
The impedance of the input source connecting to the
DC/DC power modules will interact with the modules and
affect the stability. A low ac-impedance input source is
recommended. If the source inductance is more than a
few µH, we advise adding a 33 to 100 µF electrolytic
capacitor (ESR < 0.7 Ω at 100 kHz) mounted close to the
input of the module to improve the stability.
Layout and EMC Considerations
Delta’s DC/DC power modules are designed to operate in
a wide variety of systems and applications. For design
assistance with EMC compliance and related PWB layout
issues, please contact Delta’s technical support team. An
external input filter module is available for easier EMC
compliance design. Below is the reference design for an
input filter tested with E48SP12020XXXX to meet class B
in CISSPR 22.
Schematic and Components List
E48SP12020
Vin(-)
Vo(-)
Vin
-
CX
L1
CY1
CY2
Cin
CY
Vo(+)
Vin(+)
LOAD
Cin is 100uF*2 low ESR Aluminum cap;
CX is 2.2uF ceramic cap;
CY1 are 10nF ceramic caps;
CY2 are 10nF ceramic caps;
CY is 1nF ceramic cap;
L1 is common-mode inductor, L1=0.53mH;
Test Result: Vin=48V, Io=20A,
Yellow line is quasi peak mode; Blue line is average mode.
