HBC48T25120 Datasheet, PDF (8/16 Pages) Power-One – HBC48T25120 DC-DC Converter Data Sheet

HBC48T25120 DC-DC Converter Data Sheet
36-75 VDC Input; 12 VDC @ 25 A Output
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 horizontal mountings,
efficiency, startup and shutdown 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, comprised of two-ounce copper, were used to
provide traces for connectivity to the converter.
The lack of metallization 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 derating
temperatures in the application. Thermographic
imaging is preferable; if this capability is not
available, then thermocouples may be used. The use
of AWG #40 thermocouples is recommended to
ensure measurement accuracy. Careful routing of
the thermocouple leads will further minimize
measurement error. Refer to Fig. H and Fig. I for the
optimum thermocouple locations.
Thermal Derating
Load current vs. ambient temperature and airflow
rates are given in Fig. 1 and Fig. 2 for horizontal
converter mountings, with and without baseplate
option. Ambient temperature was varied between 25
°C and 85 °C, with airflow rates from 30 to 400 LFM
(0.15 to 2.0 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 as indicated by
a thermocouple measurement, or
(ii) The output current at which the base plate
temperature does not exceed a maximum
specified temperature of 110 °C as indicated by
thermocouple measure, or
(iii) The nominal rating of the converter (25 A).
During normal operation, derating curves with
maximum FET temperature less or equal to 125 °C
should not be exceeded. Temperature at the
thermocouple location shown in Fig. H and I should
not exceed 125 °C and 110°C respectively in order
to operate inside the derating curves.
Efficiency
Fig. 3 shows the efficiency vs. load current plot for
an ambient temperature of 25 ºC, airflow rate of 300
LFM (1.5 m/s) with horizontal 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.
Power Dissipation
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 75 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.
Startup
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 Figs. 7-8, respectively.
MCD10127 Rev. 1.1, 09-Jun-10
Page 8 of 16
www.power-one.com