OKL-T/6-W5 Series
Programmable Output 6-Amp
iLGA
SMT PoLs
For best performance, we recommend installing a low-ESR capacitor
immediately adjacent to the converter’s input terminals. The capacitor
should be a ceramic type such as the Murata GRM32 series or a polymer
type. Initial suggested capacitor values are 10 to 22 μF, rated at twice the
expected maximum input voltage. Make sure that the input terminals do
not go below the undervoltage shutdown voltage at all times. More input
bulk capacitance may be added in parallel (either electrolytic or tantalum)
if needed.
Recommended Output Filtering
The converter will achieve its rated output ripple and noise with no
additional external capacitor. However, the user may install more exter-
nal output capacitance to reduce the ripple even further or for improved
dynamic response. Again, use low-ESR ceramic (Murata GRM32 series)
or polymer capacitors. Initial values of 10 to 47 μF may be tried, either
single or multiple capacitors in parallel. Mount these close to the converter.
Measure the output ripple under your load conditions.
Use only as much capacitance as required to achieve your ripple and
noise objectives. Excessive capacitance can make step load recovery
sluggish or possibly introduce instability. Do not exceed the maximum rated
output capacitance listed in the specifications.
Input Ripple Current and Output Noise
All models in this converter series are tested and specified for input
reflected ripple current and output noise using designated external input/
output components, circuits and layout as shown in the figures below. The
Cbus and Lbus components simulate a typical DC voltage bus. Please note
that the values of Cin, Lbus and Cbus will vary according to the specific
converter model.
TO
OSCILLOSCOPE
COPPER STRIP
+OUTPUT
C1
C2
SCOPE
R
LOAD
-OUTPUT
COPPER STRIP
C1 = 1μF CERAMIC
C2 = 10μF CERAMIC
LOAD 2-3 INCHES (51-76mm) FROM MODULE
Figure 5: Measuring Output Ripple and Noise (PARD)
Minimum Output Loading Requirements
All models regulate within specification and are stable under no load to full
load conditions. Operation under no load might however slightly increase
output ripple and noise.
Temperature Derating Curves
The graphs in the next section illustrate typical operation under a variety of
conditions. The Derating curves show the maximum continuous ambient air
temperature and decreasing maximum output current which is accept-
able under increasing forced airflow measured in Linear Feet per Minute
(“LFM”). Note that these are AVERAGE measurements. The converter will
accept brief increases in current or reduced airflow as long as the average
is not exceeded.
Note that the temperatures are of the ambient airflow, not the converter
itself which is obviously running at higher temperature than the outside
air. Also note that very low flow rates (below about 25 LFM) are similar to
“natural convection”, that is, not using fan-forced airflow.
Murata Power Solutions makes Characterization measurements in a
closed cycle wind tunnel with calibrated airflow. We use both thermo-
couples and an infrared camera system to observe thermal performance.
CURRENT
PROBE
+INPUT
L
BUS
C
BUS
C
IN
V
IN
+
–
+
–
-INPUT
C
IN
= 2 x 100μF, ESR < 700mΩ @ 100kHz
C
BUS
= 1000μF, ESR < 100mΩ @ 100kHz
L
BUS
= 1μH
Figure 4: Measuring Input Ripple Current
In figure 5, the two copper strips simulate real-world printed circuit
impedances between the power supply and its load. In order to minimize
circuit errors and standardize tests between units, scope measurements
should be made using BNC connectors or the probe ground should not
exceed one half inch and soldered directly to the test circuit.
www.murata-ps.com
13 May 2010
email: sales@murata-ps.com
MDC_OKL-T/6-W5 Series.A02
Page 6 of 15
MURATA-PS [ MURATA POWER SOLUTIONS INC. ]
