NQB-420DWA-AN Datasheet, PDF (24/36 Pages) CUI INC – FULLY REGULATED ADVANCED BUS CONVERTERS

CUI Inc │ SERIES: NQB-D │ DESCRIPTION: FULLY REGULATED ADVANCED BUS CONVERTERS
date 02/20/2013 │ page 24 of 36
Output Voltage Regulation
The NQB products are designed to be fully regulated
within the plotted area. Operating outside this area is not
recommended.
are found in the output section for each model. The
product is tested in a sealed box test set up with ambient
temperatures 85, 55 and 25°C.
13.4
13.2
13.0
12.8
12.6
12.4
12.2
12.0
35 45 55 65 75
Vin [V]
Vin range: 36-75Vdc
13.4
13.2
13.0
12.8
12.6
12.4
12.2
12.0
35 40 45 50 55 60 65
Vin [V]
Vin range:40-60Vdc
Thermal Consideration
General
The product is designed to operate in different thermal
environments and sufficient cooling must be provided
to ensure reliable operation. For products mounted on
a PWB without a heat sink attached, cooling is achieved
mainly by conduction, from the pins to the host board,
and convection, which is dependant on the airflow across
the product. Increased airflow enhances the cooling of
the product. The Output Current Derating graph found in
the output section for each model provides the available
output current vs. ambient air temperature and air velocity
at V_I =53 V.
The product is tested on a 254 x 254 mm, 35 µm (1 oz),
16-layer test board mounted vertically in a wind tunnel
with a cross-section of 608 x 203 mm.
Definition of product operating temperature
The product operating temperature is used to monitor the
temperature of the product, and proper thermal conditions
can be verified by measuring the temperature at positions
P1, P2, P3 and P4. The temperature at these positions (T_P1,
T_P2, T_P3, T_P4) should not exceed the maximum temperatures
in the table below. The number of measurement points
may vary with different thermal design and topology.
Temperatures above maximum T_P1, measured at the
reference point P1 (T_P3 / _P3 for base plate versions) are not
allowed and may cause permanent damage.
Position
P1
P2
P3
P4
Description
Max temperature
PWB (reference point, open
frame)
T_P1=125º C
Opto-coupler
T_P2=105º C
PWB (reference point for
base-plate version)
T_P3=125º C
Primary MOSFET
T_P4=125º C
For products with base plate used in a sealed box/cold
wall application, cooling is achieved mainly by conduction
through the cold wall. The Output Current Derating graphs
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