QME48T20120-NGB0 POWER ONE, QME48T20120-NGB0 Datasheet - Page 8

• Manufacturer Part Number: QME48T20120-NGB0
• Description: Module DC-DC 1-OUT 12V 20A 8-Pin Quarter-Brick
• Manufacturer: POWER ONE
• Type: Step Downr

Specifications of QME48T20120-NGB0

• Package: 8Quarter-Brick
• Output Current: 20 A
• Output Voltage: 12 V
• Input Voltage: 48 V
• Number Of Outputs: 1
• Switching Regulator: Yes

Characterization
Test Conditions
General Information
The converter has been characterized for many
operational aspects, to include thermal derating
(maximum load current as a function of ambient
temperature and airflow) for vertical and horizontal
mountings,
parameters, output ripple and noise, transient
response to load step-change, overload, and short
circuit.
The following pages contain specific plots or
waveforms associated with the converter. Additional
comments for specific data are provided below.
soldered to a test board, specifically a 0.060” thick
printed wiring board (PWB) with four layers. The top
and bottom layers were not metalized. The two inner
layers, comprised of two-ounce copper, were used to
provide traces for connectivity to the converter.
The lack of metalization on the outer layers as well
as the limited thermal connection ensured that heat
transfer from the converter to the PWB was
minimized. This provides a worst-case but consistent
scenario for thermal derating purposes.
All measurements requiring airflow were made in the
vertical and horizontal wind tunnel using Infrared (IR)
thermography and thermocouples for thermometry.
Ensuring components on the converter do not
exceed their ratings is important to maintaining high
reliability. If one anticipates operating the converter
at or close to the maximum loads specified in the
derating curves, it is prudent to check actual
operating
Thermographic
capability is not available, then thermocouples may
be used. The use of AWG #40 gauge thermocouples
is recommended to ensure measurement accuracy.
Careful routing of the thermocouple leads will further
minimize measurement error. Refer to Fig. H for the
optimum measuring thermocouple location.
ZD-01742 Rev 3.4, 21-Jan-10
All data presented were taken with the converter
Fig. H: Location of the thermocouple for thermal testing.
temperatures
efficiency,
imaging
startup
is
in
preferable;
the
and
application.
shutdown
if
www.power-one.com
QME48T20120 DC-DC Converter Data Sheet
this
36-75 VDC Input; 12 VDC @ 20 A Output
Load current vs. ambient temperature and airflow
rates are given in Fig. 1 and Fig. 2 for vertical and
horizontal converter mountings. Ambient temperature
was varied between 25 °C and 85 °C, with airflow
rates from 30 to 500 LFM (0.15 to 2.5 m/s).
For each set of conditions, the maximum load current
was defined as the lowest of:
(i) The output current at which any FET junction
temperature does not exceed a maximum specified
temperature of 125 °C
thermographic image, or
(ii) The nominal rating of the converter (20 A).
During
maximum FET temperature less or equal to 125 °C
should not be exceeded. Temperature at the
thermocouple location shown in Fig. H should not
exceed 125 °C in order to operate inside the derating
curves.
Fig. 3 shows the efficiency vs. load current plot for
ambient temperature of 25 ºC, airflow rate of 300 LFM
(1.5 m/s) with vertical mounting and input voltages of
36 V, 48 V and 72 V. Also, a plot of efficiency vs. load
current, as a function of ambient temperature with
Vin = 48 V, airflow rate of 200 LFM (1 m/s) with
vertical mounting is shown in Fig. 4.
Fig. 5 shows the power dissipation vs. load current
plot for Ta = 25 ºC, airflow rate of 300 LFM (1.5 m/s)
with vertical mounting and input voltages of 36 V, 48 V
and 72 V. Also, a plot of power dissipation vs. load
current, as a function of ambient temperature with
Vin = 48 V, airflow rate of 200 LFM (1 m/s) with
vertical mounting is shown in Fig. 6.
Output
transient using the ON/OFF pin for full rated load
currents (resistive load) are shown without and with
external load capacitance in Figs. 7-8, respectively.
Fig. 11 show the output voltage ripple waveform,
measured at full rated load current with a 10 µF
tantalum and 1 µF ceramic capacitor across the
output. Note that all output voltage waveforms are
measured across a 1 µF ceramic capacitor.
The input reflected ripple current waveforms are
obtained using the test setup shown in Fig 12. The
corresponding waveforms are shown in Figs. 13-14.
Thermal Derating
Efficiency
Power Dissipation
Startup
Ripple and Noise
normal
voltage
operation,
waveforms,
as
derating
during
indicated
Data Sheet
curves
the
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