QTS48T25120 DC-DC Series Data Sheet
300-Watt Quarter-Brick Bus Converter
based standards, one of the following requirements
must be met in the system design:
Safety Considerations
•
If the voltage source feeding the module is SELV
or TNV, the output of the converter may be
grounded or ungrounded.
The QTS48T25120 converter features 2000 Volt DC
isolation from input to output. The input-to-output
resistance is greater than 10MΩ. This converter is
provided with functional insulation between input and
output circuits according to all IEC60950 based
standards. Nevertheless, if the system using the
converter needs to receive safety agency approval,
certain rules must be followed in the design of the
system. In particular, all of the creepage and
clearance requirements of the end-use safety
requirements must be observed. These documents
include UL60950 - CSA60950-00 and EN60950,
although other or additional requirements may be
needed for specific applications.
•
If the voltage source feeding the module is ELV,
the output of the converter may be considered
SELV only if the output is grounded per the
requirements of the standard.
•
This information is provided for guidance only
and the user is responsible for any design
considerations regarding safety.
Thermal Considerations
The QTS48T25120 converter is designed for natural
or forced convection cooling.
The maximum
The QTS48T25120 converter has no internal fuse.
The external fuse must be provided to protect the
system from catastrophic failure as shown in Figure
2. The fuse with a rating not greater than 10A is
recommended. The user can select a lower rating
fuse based upon the highest inrush transient at the
maximum input voltage and the maximum input
current of the converter, which occurs at the
minimum input voltage. 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, if any.
allowable output current of the converter is
determined by meeting the derating criteria for all
components used in the converter. For example, the
maximum semiconductor junction temperature is not
allowed to exceed 125°C to ensure reliable long-term
operation of the converter. Contact Power-One for
the complete list of the derating criteria.
The graph in figure 3 shows the maximum output
current of the QTS48T25120 converter at different
ambient temperatures under both natural and forced
(transverse airflow direction, from pin 1 to pin 3)
convection.
For example, the QTS48T25120 operating at 48Vin,
70°C can deliver up to 21A reliably with 200LFM
forced air.
In order for the output of the QTS48T25120
converter to be considered as SELV (Safety Extra
Low Voltage) or TNV-1, according to all IEC60950
MAY 31, 2005 revised to JUN 15, 2006
Page 5 of 8
www.power-one.com
