WPA60R48DC Datasheet, PDF (5/31 Pages) Murata Power Solutions Inc. – 60 Watt Dual Output Quarter Brick DC/DC Converter

APPLICATION NOTES
Input Under-Voltage Shutdown
Performance Characterization
The nominal input voltage for the WPA60C is 48Vdc.
At an input voltage of 32.5Vdc nominal the unit will
shutdown on an input under-voltage condition. At an
input voltage less than 32.5V the under-voltage sensing
circuit will send a signal to the PWM causing it to go
into idle mode. This will result in no output from the
converter, protecting the unit from a high input current
condition. When the input voltage returns to a level
above 32.5V the unit will return to normal operation. The
unit will typically turn on at an input voltage of 34.5V
nominal as indicated on the Product Data Sheet. This
is due to hysterisis designed into the protective circuit to
prevent excessive cycling of the converter.
Thermal Derating
Maximum ouput current vs. ambient temperature
at various airflow rates has been determined for
each model of the WPA60C. From these graphs,
the combination of maximum ambient temperature
and minimum airflow for select output current
combinations can be determined. Each model was
analyzed for maximum allowable output power over
an ambient temperature range of 0 to 85^oC and for
airflows up to 600LFM. In each case the maximum
allowable power at a given airflow and ambient
temperature is defined as the point at which a known
component reaches its individual temperature limit.
Over-Current Protection
To protect against fault or short-circuit conditions on the
output, each module is equipped with current-limiting
circuitry designed to provide continuous protection. After
reaching the current limit point (typically 20% above the
rated output current), the voltage will range between its
rated value and zero, depending upon the amount of
overload. The unit will remain in operation continuously
during this period down to a short-circuit condition.
Once the short or overload has been eliminated, the
output voltage will return to normal without cycling the
input power.
Safety
The WPA60C meets safety requirements per UL/
CUL 60950 and VDE to EN60950. Additionally, the
converter meets CISPR22/ EN55022/ FCC15J Class B
specs for EMI levels with external filtering.
Efficiency
Efficiency data for each model was determined
as a function of Load Current and Input Voltage.
Efficiency vs. Load Current was measured at an
ambient temperature of 25^oC, an airflow of 300LFM
with an input voltage of 48Vdc. Efficiency vs. Input
Voltage was measured at an ambient temperature of
25^oC, an airflow of 300LFM and rated load. Graphs
for each model are provided in their respective
section.
Start-Up, ON/OFF and Transient Response
For each model, waveforms are provided showing
output voltage response and timing to input voltage
power up/down, Remote ON/OFF state change and
load current transient responses. Separate traces
are provided showing the on/off timing sequence
of the two outputs relative to one another. Output
voltage transient responses are provided for step
load changes of 50% - 100% of rated load current
and 100% - 50% of rated load. Waveforms for each
model are provided in their respective section.
Product: www.cd4power.com
WPA60R48DC REV A: RoHS 08/2006
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