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 is grounded
,
one Vi pin and
one Vo pin shall also be 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 normal-blow fuse with 10A 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 are 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
µ
H, we advise adding a 10 to 100
µ
F 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. Application notes to
assist designers in addressing these issues are pending
to release.
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,
CAN/CSA-C22.2 No. 60950-00 and EN60950: 2000 and
IEC60950-1999, 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:
DS_L36SA3R315_02142007
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