YM12S05 DC-DC Converter Data Sheet
9.6-14 VDC Input; 0.7525-5.5 VDC Programmable @ 5A
parameters, output ripple and noise, transient
Thermal Derating
response to load step-change, overload and short
circuit.
Load current vs. ambient temperature and airflow
rates are given in Figs. x.1 to x.2 for maximum
temperature of 120 °C. Ambient temperature was
varied between 25 °C and 85 °C, with airflow rates
from 30 to 500 LFM (0.15m/s to 2.5 m/s), and
vertical and horizontal converter mounting.
The figures are numbered as Fig. x.y, where x
indicates the different output voltages, and y
associates with specific plots (y = 1 for the vertical
thermal derating, …). For example, Fig. x.1 will refer
to the vertical thermal derating for all the output
voltages in general.
For each set of conditions, the maximum load
current is defined as the lowest of:
The following pages contain specific plots or
waveforms associated with the converter. Additional
comments for specific data are provided below.
(i) The output current at which any MOSFET
temperature does not exceed a maximum specified
temperature (120°C) as indicated by the
thermographic image, or
Test Conditions
(ii) The maximum current rating of the converter (5A)
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.
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. C
should not exceed 120 °C in order to operate inside
the derating curves.
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.
Efficiency
Figure x.3 shows the efficiency vs. load current plot
for ambient temperature of 25 ºC, airflow rate of 200
LFM (1 m/s) and input voltages of 9.6V, 12V and
14V.
All measurements requiring airflow were made in the
vertical and horizontal wind tunnel facilities using
Infrared (IR) thermography and thermocouples for
thermometry.
Power Dissipation
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
Fig. x.4 shows the power dissipation vs. load current
plot for Ta = 25ºC, airflow rate of 200 LFM (1 m/s)
with vertical mounting and input voltages of 9.6V,
12V and 14V.
Ripple and Noise
operating
temperatures
in
the
application.
Thermographic imaging is preferable; if this
capability is not available, then thermocouples may
be used. . It is recommended the use of AWG #40
gauge thermocouples to ensure measurement
accuracy. Careful routing of the thermocouple leads
will further minimize measurement error. Refer to
The output voltage ripple waveform is measured at
full rated load current. Note that all output voltage
waveforms are measured across a 1 F ceramic
capacitor.
The output voltage ripple and input reflected ripple
current waveforms are obtained using the test setup
shown in Fig. D.
Fig.
C
for optimum measuring thermocouple
locations.
iS
Vin
Vout
1 H
source
inductance
Y-Series
CIN
47F
ceramic
capacitor
1F
ceramic
capacitor
CO
Vout
DC/DC
Converter
47F
ceramic
capacitor
Vsource
GND
GND
Fig. D: Test setup for measuring input reflected ripple
currents, is and output voltage ripple.
Fig. C: Location of the thermocouple for thermal testing.
MCD10132 Rev. 1.1, 21-Jun-10
Page 7 of 24
www.power-one.com
QQ：1902134819 复制
