Datasheet

ULS 100-Watt Series
Sixteenth-brick DOSA-Compatible,
Isolated DC-DC Converters
MDC_ULS-100 Series.A09 Page 16 of 28
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Functional Specifi cation Notes
➀ All specifi cations are typical unless noted. Ambient temperature =
+25°Celsius, V
IN is nominal, output current is maximum rated nominal.
External output capacitance is 1 µF multilayer ceramic paralleled with
10µF electrolytic. All caps are low ESR. These capacitors are necessary for
our test equipment and may not be needed in your application.
Testing must be kept short enough that the converter does not appreciably
heat up during testing. For extended testing, use plenty of airfl ow. See
Derating Curves for temperature performance. All models are stable and
regulate within spec without external cacacitance.
➁ Input Ripple Current is tested and specifi ed over a 5-20 MHz bandwidth
and uses a special set of external fi lters only for the Ripple Current speci-
fi cations. Input fi ltering is C
IN = 33 µF, CBUS = 220 µF, LBUS = 12µH. Use
capacitor rated voltages which are twice the maximum expected voltage.
Capacitors must accept high speed AC switching currents.
➂ Note that Maximum Current Derating Curves indicate an average current
at nominal input voltage. At higher temperatures and/or lower airfl ow, the
converter will tolerate brief full current outputs if the average RMS current
over time does not exceed the Derating curve. All Derating curves are
presented at sea level altitude. Be aware of reduced power dissipation
with increasing density altitude.
➃ Mean Time Before Failure (MTBF) is calculated using the Telcordia
(Belcore) SR-332 Method 1, Case 3, Issue 1, ground fi xed conditions. Oper-
ating temperature = +25°C, full output load, natural air convection.
➄ The output may be shorted to ground indefi nitely with no damage. The
Output Short Circuit Current shown in the specifi cations is an average con-
sisting of very short bursts of full rated current to test whether the output
circuit can be repowered.
➅ The On/Off Control is normally driven from a switch or relay. An open
collector/open drain transistor may be used in saturation and cut-off
(pinch-off) modes. External logic may also be used if voltage levels are
fully compliant to the specifi cations.
➆ Regulation specifi cations describe the deviation as the input line voltage
or output load current is varied from a nominal midpoint value to either
extreme (50% load).
➇ Do not exceed maximum power ratings, Sense limits or output overvoltage
when adjusting output trim values.
➈ At zero output current, Vout may contain components which slightly
exceed the ripple and noise specifi cations.
➉ Output overload protection is non-latching. When the output overload
is removed, the output will automatically recover.
All models are fully operational and meet published specifi cations,
including “cold start” at –40°C.
The converter will shut off if the input falls below the undervoltage thresh-
old. It will not restart until the input exceeds the Input Start Up Voltage.
Short circuit shutdown begins when the output voltage degrades approxi-
mately 2% from the selected setting.
Output noise may be further reduced by installing an external fi lter. See
the Application Notes. Use only as much output fi ltering as needed and no
more. Larger caps (especially low-ESR ceramic types) may slow transient
response or degrade dynamic performance. Thoroughly test your applica-
tion with all components installed.
To avoid damage or unplanned shutdown, do not sink appreciable reverse
output current.
A fast blow fuse must be installed in series with +Vin to avoid damage to
the converter in the event that the source voltage is accidentally applied to
the converter with reverse polarity.
Although extremely unlikely, failure of the internal components of this
product may expose external application circuits to dangerous voltages,
currents, temperatures or power levels. Please thoroughly verify all appli-
cations before committing them to service. Be sure to include appropri-
ately rated FUSES (see specifi cations and Application Notes) to reduce the
risk of failure.
If Sense is not wired to an external load, connect sense pins to their
respective Vout pins. Do not leave sense unconnected.
The switching frequencies of these converters are fi xed; see individual
specifi cations for model details.
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