ZD-02084 Rev. 1.2
www.power-one.com
Page 6 of 12
SSQE48T25015 DC-DC Converter Data Sheet
36-75 VDC Input; 1.5 VDC, 25 A Output
Data Sheet
Protection Features
Input Undervoltage Lockout
Input undervoltage lockout is standard with this
converter. The converter will shut down when the
input voltage drops below a pre-determined voltage.
The input voltage must be typically 34 V for the
converter to turn on. Once the converter has been
turned on, it will shut off when the input voltage
drops typically below 32 V. This feature is beneficial
in preventing deep discharging of batteries used in
telecom applications.
Output Overcurrent Protection (OCP)
The converter is protected against overcurrent or
short circuit conditions. Upon sensing an overcurrent
condition, the converter will switch to constant
current operation and thereby begin to reduce output
voltage. During short circuit, when the output voltage
drops below 50% its nominal value, the converter will
shut down.
Once the converter has shut down, it will attempt to
restart nominally every 200 ms with a very low duty
cycle. The attempted restart will continue indefinitely
until the overload or short circuit conditions are
removed.
Once the output current is brought back into its
specified range, the converter automatically exits the
hiccup mode and continues normal operation.
Output Overvoltage Protection (OVP)
The converter will shut down if the output voltage
across Vout(+) (Pin 8) and Vout(-) (Pin 4) exceeds
the threshold of the OVP circuitry. The OVP circuitry
contains its own reference, independent of the output
voltage regulation loop. Once the converter has shut
down, it will attempt to restart every 200 ms until the
OVP condition is removed.
Overtemperature Protection (OTP)
The
converter
will
shut
down
under
an
overtemperature condition to protect itself from
overheating caused by operation outside the thermal
derating curves, or operation in abnormal conditions
such
as
system
fan
failure.
Converter
will
automatically restart after it has cooled to a safe
operating temperature.
Safety Requirements
The
converters
meet
North
American
and
International safety regulatory requirements per
UL60950 and EN60950. Basic Insulation is provided
between input and output.
The converters have no internal fuse. If required, the
external fuse needs to be provided to protect the
converter from catastrophic failure.
Refer to the
“Input Fuse Selection for DC/DC converters”
selection of the input fuse. Both input traces and the
chassis ground trace (if applicable) must be capable
of conducting a current of 1.5 times the value of the
fuse without opening. The fuse must not be placed
in the grounded input line.
Abnormal
and
component
failure
tests
were
conducted with the input protected by an external
UL-listed fuse, rated 20A.
If a fuse rated greater
than 20A is used, additional testing may be required.
To protect a group of converters with a single fuse,
the rating can be increased from the recommended
value above.
Electromagnetic Compatibility (EMC)
EMC requirements must be met at the end-product
system level, as no specific standards dedicated to
EMC characteristics of board mounted component
DC-DC converters exist. However, Power-One tests
its converters to several system level standards,
primary of which is the more stringent EN55022,
Information
technology
equipment
-
Radio
disturbance characteristics-Limits and methods of
measurement.
An effective internal LC differential filter significantly
reduces input reflected ripple current, and improves
EMC.
With the addition of a simple external filter, all
versions of the SSQE48T25015 converters pass the
requirements of Class B conducted emissions per
EN55022 and FCC requirements. Please contact
Power-One Applications Engineering for details of
this testing.