UQQ-12 Datasheet, PDF (13/18 Pages) Murata Manufacturing Co., Ltd. – Wide Input Range Single Output DC-DC Converters

UQQ Series
Wide Input Range Single Output DC-DC Converters
TECHNICAL NOTES
Soldering Guidelines
Murata Power Solutions recommends the specifications below when installing these
converters. These specifications vary depending on the solder type. Exceeding these
specifications 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
Maximum Pot Temperature
270° C. Maximum Pot Temperature
Maximum Solder Dwell Time 7 seconds Maximum Solder Dwell Time
105° C.
250° C.
6 seconds
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 first.
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/specified for input ripple current (also
called input reflected ripple current) and output noise using the circuits and
layout shown in Figures 2 and 3. External input capacitors (CIN in Figure 2)
serve primarily as energy-storage elements.
TO
OSCILLOSCOPE
+
VIN
–
LBUS
CBUS
CURRENT
PROBE ₁
CIN
3
CIN = 33µF, ESR < 700mΩ @ 100kHz
CBUS = 220µF, ESR < 100mΩ @ 100kHz
LBUS = 12µH
+VIN
–VIN
Figure 2. Measuring Input Ripple Current
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, CBUS and LBUS simulate a typical dc voltage bus. Your specific
system configuration may necessitate additional considerations.
In critical applications, output ripple/noise (also referred to as periodic and
random deviations or PARD) can be reduced below specified limits using
filtering techniques, the simplest of which is the installation of additional
external output capacitors. Output capacitors function as true filter 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.
+SENSE ⁷
8
+VOUT
C1
4
–VOUT
5
–SENSE
C2
SCOPE
RLOAD
C1 = 1µF
C2 = 10µF TANTALUM
LOAD 2-3 INCHES (51-76mm) FROM MODULE
Figure 3. Measuring Output Ripple/Noise (PARD)
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MDC_UQQ.D03 Page 13 of 18