Datasheet

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UQQ Series
Wide Input Range Single Output DC-DC Converters
MDC_UQQ.D05 Page 13 of 18
Removal of Soldered UQQ’s from Printed Circuit Boards
Should removal of the UQQ from its soldered connection be needed, thor-
oughly de-solder the pins using solder wicks or de-soldering tools. At no time
should any prying or leverage be used to remove boards that have not been
properly de-soldered fi rst.
Input Source Impedance
UQQ converters must be driven from a low ac-impedance input source. The
DC-DC’s performance and stability can be compromised by the use of highly
inductive source impedances. The input circuit shown in Figure 2 is a practical
solution that can be used to minimize the effects of inductance in the input
traces. For optimum performance, components should be mounted close to the
DC-DC converter.
I/O Filtering, Input Ripple Current, and Output Noise
All models in the UQQ Series are tested/specifi ed for input ripple current (also
called input refl ected ripple current) and output noise using the circuits and
layout shown in Figures 2 and 3. External input capacitors (C
IN in Figure 2)
serve primarily as energy-storage elements.
Figure 2. Measuring Input Ripple Current
C
IN
V
IN
C
BUS
L
BUS
C
IN
= 33µF, ESR < 700mΩ @ 100kHz
C
BUS
= 220µF, ESR < 100mΩ @ 100kHz
L
BUS
= 12µH
1
3
+VIN
–VIN
CURRENT
PROBE
TO
OSCILLOSCOPE
+
TECHNICAL NOTES
They should be selected for bulk capacitance (at appropriate frequencies),
low ESR, and high rms-ripple-current ratings. The switching nature of
DC-DC converters requires that dc voltage sources have low ac imped-
ance as highly inductive source impedance can affect system stability.
In Figure 2, C
BUS and LBUS simulate a typical dc voltage bus. Your specifi c
system confi guration may necessitate additional considerations.
In critical applications, output ripple/noise (also referred to as periodic and
random deviations or PARD) can be reduced below specifi ed limits using
ltering techniques, the simplest of which is the installation of additional
external output capacitors. Output capacitors function as true fi lter ele-
ments and should be selected for bulk capacitance, low ESR, and appropri-
ate frequency response.
All external capacitors should have appropriate voltage ratings and be
located as close to the converter as possible. Temperature variations for all
relevant parameters should be taken into consideration. OS-CON
TM
organic
semiconductor capacitors (www.sanyo.com) can be especially effective for
further reduction of ripple/noise. The most effective combination of external
I/O capacitors will be a function of line voltage and source impedance, as
well as particular load and layout conditions.
Figure 3. Measuring Output Ripple/Noise (PARD)
C1
C1 = 1µF
C2 = 10µF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE
C2
R
LOAD
7
8
4
5
SCOPE
+VOUT
–VOUT
+SENSE
–SENSE
Soldering Guidelines
Murata Power Solutions recommends the specifi cations below when installing these
converters. These specifi cations vary depending on the solder type. Exceeding these
specifi cations may cause damage to the product. Your production environment may dif-
fer; therefore please thoroughly review these guidelines with your process engineers.
Wave Solder Operations for through-hole mounted products (THMT)
For Sn/Ag/Cu based solders: For Sn/Pb based solders:
Maximum Preheat Temperature 115° C. Maximum Preheat Temperature 105° C.
Maximum Pot Temperature 270° C. Maximum Pot Temperature 250° C.
Maximum Solder Dwell Time 7 seconds Maximum Solder Dwell Time 6 seconds