SQ24X03150 Power-One, SQ24X03150 Datasheet - Page 7

• Manufacturer Part Number: SQ24X03150
• Description: Sq24t/s03150 Dc-dc Converter 19-36 Vdc Input; 15 Vdc Output @ 3.3 A
• Manufacturer: Power-One

Characterization
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
mounting,
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.
Test Conditions
All data presented were taken with the converter
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, comprising 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
vertical and horizontal wind tunnels using Infrared
(IR)
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. Power-One recommends the use of AWG
#40 gauge thermocouples to ensure measurement
accuracy. Careful routing of the thermocouple leads
will further minimize measurement error. Refer to
Figure H for optimum measuring thermocouple
location.
Thermal Derating
Load current vs. ambient temperature and airflow
rates are given in Fig. 1 to Fig. 4 for through-hole
and surface mount version. Ambient temperature
was varied between 25°C and 85°C, with airflow
JAN 21, 2004 revised to AUG 23, 2006
thermography
efficiency,
temperatures
imaging
and
start-up
is
in
thermocouples
preferable;
the
and
application.
shutdown
if
SQ24T/S03150 DC-DC Converter Data Sheet
this
for
Page 7 of 15
19-36 VDC Input; 15 VDC Output @ 3.3 A
rates from 30 to 500 LFM (0.15 to 2.5 m/s), and
vertical and horizontal converter mounting.
For each set of conditions, the maximum load
current was defined as the lowest of:
(i) The output current at which either any FET
junction temperature did not exceed a maximum
specified temperature (120 °C) as indicated by the
thermographic image, or
(ii) The nominal rating of the converter (3.3 A).
During normal operation, derating curves with
maximum FET temperature less than or equal to
120 °C should not be exceeded. Temperature on the
PCB at the thermocouple location shown in Fig. H
should not exceed 118 °C in order to operate inside
the derating curves.
Efficiency
Fig. 5 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 18 V, 24 V, and 36 V. Also, a plot of
efficiency vs. load current, as a function of ambient
temperature with Vin = 24 V, airflow rate of 200 LFM
(1 m/s) with vertical mounting is shown in Fig. 6.
Power Dissipation
Fig. 7 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 18 V,
24 V, and 36 V. Also, a plot of power dissipation vs.
load current, as a function of ambient temperature
with Vin = 24 V, airflow rate of 200 LFM (1 m/s) with
vertical mounting is shown in Fig. 8.
Start-up
Output voltage waveforms, during the turn-on
transient using the ON/OFF pin for full rated load
currents (resistive load) are shown without and with
external load capacitance in
respectively.
Ripple and Noise
Fig. 13 shows 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 14. The
corresponding waveforms are shown in Fig. 15 and
Fig. 16.
Fig. 9 and Fig. 10,
www.power-one.com