UWE Series
Wide Input, Isolated
Eighth-Brick DC/DC Converters
Soldering Guidelines
Undervoltage Shutdown limit. Subsequent re-start will not occur until the input
is brought back up to the Start-Up Threshold. This built in hysteresis prevents
any unstable on/off situations from occurring at a single input voltage.
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. Be cautious when there is high atmo-
spheric humidity. We strongly recommend a mild pre-bake (100° C. for 30 minutes). Your
production environment may differ; therefore please thoroughly review these guidelines
Start-Up Time
The VIN to VOUT Start-Up Time is the interval of time between the point at which
the ramping input voltage crosses the Start-Up Threshold and the fully loaded
output voltage enters and remains within its specified accuracy band. Actual
measured times will vary with input source impedance, external input/output
capacitance, and load. The UWE Series implements a soft start circuit that
limits the duty cycle of its PWM controller at power up, thereby limiting the
input inrush current.
with your process engineers.
Wave Solder Operations for through-hole mounted products (THMT)
For Sn/Ag/Cu based solders:
Maximum Preheat Temperature
Maximum Pot Temperature
Maximum Solder Dwell Time
For Sn/Pb based solders:
Maximum Preheat Temperature
Maximum Pot Temperature
Maximum Solder Dwell Time
115° C.
270° C.
7 seconds
The On/Off Control to VOUT start-up time assumes the converter has its
nominal input voltage applied but is turned off via the On/Off Control pin. The
specification defines the interval between the point at which the converter is
turned on and the fully loaded output voltage enters and remains within its
specified accuracy band. Similar to the VIN to VOUT start-up, the On/Off Control
to VOUT start-up time is also governed by the internal soft start circuitry and
external load capacitance.
105° C.
250° C.
6 seconds
Absolute Maximum Ratings
Input Voltage
Q12 Models - Volts, max. continuous
Volts, transient, 100 mSec
Q48 Models - Volts, max. continuous
0-36 VDC
0-50 VDC
0-75 VDC
The difference in start up time from VIN to VOUT and from On/Off Control to
VOUT is therefore insignificant.
Volts, transient, 100 mSec
On/Off Control
0-100 VDC
-0.7 V. min to +15V max.
Input Source Impedance
UWE 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. For optimum performance, compo-
nents should be mounted close to the DC/DC converter. If the application
has a high source impedance, low VIN models can benefit from increased
external input capacitance.
Input Reverse Polarity Protection
Output Overvoltage
See Fuse section.
Vout nom. +20ꢀ max.
Output Current (Note 7)
Devices can
Current-limited.
withstand sustained short circuit
without damage.
Overtemperature Protection
Device includes electronic over-
temperature shutdown protection
under normal operation.
-55 to +125° C.
I/O Filtering, Input Ripple Current, and Output Noise
Storage Temperature
Lead Temperature
All models in the UWE Converters are tested/specified for input reflected ripple
current and output noise using the specified external input/output components/
circuits and layout as shown in the following two figures.
See soldering specifications
Absolute maximums are stress ratings. Exposure of devices to greater than any of these
conditions may adversely affect long-term reliability. Proper operation under conditions
other than those listed in the Performance/Functional Specifications Table is not implied or
recommended.
External input capacitors (CIN in Figure 2) serve primarily as energy-storage
elements, minimizing line voltage variations caused by transient IR drops in
conductors from backplane to the DC/DC. Input caps 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 impedance 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.
TECHNICAL NOTES
Input Fusing
Certain applications and/or safety agencies may require the installation of
fuses at the inputs of power conversion components. Fuses should also be
used if the possibility of sustained, non-current-limited, input-voltage polarity
reversals exist. For MPS UWE DC/DC Converters, you should use slow-blow
type fuses, installed in the ungrounded input supply line. Refer to the specifica-
tions for fuse values.
TO
CURRENT
PROBE
OSCILLOSCOPE
+INPUT
LBUS
+
All relevant national and international safety standards and regulations must
be observed by the installer. For system safety agency approvals, the convert-
ers must be installed in compliance with the requirements of the end-use
safety standard, e.g., IEC/EN/UL60950-1.
VIN
CBUS
CIN
–
–INPUT
CIN = 33μF, ESR < 700mΩ @ 100kHz
CBUS = 220μF, ESR < 100mΩ @ 100kHz
LBUS = 12μH
Input Undervoltage Shutdown and Start-Up Threshold
Under normal start-up conditions, devices will not begin to regulate until
the ramping-up input voltage exceeds the Start-Up Threshold Voltage. Once
operating, devices will not turn off until the input voltage drops below the
Figure 2. Measuring Input Ripple Current
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Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000
MDC_UWE Series.A17 Page 9 of 20
