UEI25-120-D48N-C Murata Power Solutions Inc, UEI25-120-D48N-C Datasheet - Page 20

• Manufacturer Part Number: UEI25-120-D48N-C
• Description: CONV DC/DC 25W 12V
• Manufacturer: Murata Power Solutions Inc
• Series: UEI25-120r
• Type: Isolatedr

Specifications of UEI25-120-D48N-C

• Number Of Outputs: 1
• Output: 12V
• Power (watts): 25W
• Mounting Type: Through Hole
• Voltage - Input: 36 ~ 75V
• Package / Case: 6-DIP Module
• 1st Output: 12 VDC @ 2.1A
• Size / Dimension: 1.10" L x 0.96" W x 0.32" H (27.9mm x 24.4mm x 8.1mm)
• Power (watts) - Rated: 25W
• Operating Temperature: -40°C ~ 85°C
• Efficiency: 87.5%
• Approvals: CAN, CSA, EN, IEC, UL
• Output Power: 25.2 W
• Input Voltage Range: 36 V to 75 V
• Input Voltage (nominal): 48 V
• Output Voltage (channel 1): 12 V
• Output Current (channel 1): 2.1 A
• Package / Case Size: 24.38 mm x 27.94 mm x 8.13 mm
• Output Type: DC/DC Converter
• Output Voltage: 12 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• 3rd Output: -
• 2nd Output: -
• 4th Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 811-2222

the ground return of the load circuit. You can however use the positive output
(+Output) as the ground return to effectively reverse the output polarity.
Minimum Output Loading Requirements
These converters employ a synchronous rectifi er design topology. All models
regulate within specifi cation and are stable from 0% load to full load conditions,
unless otherwise specifi ed. Operation under no load will not damage the con-
verter but might, however, slightly increase regulation, output ripple, and noise.
Thermal Shutdown
To protect against thermal over-stress, these converters include thermal shut-
down circuitry. If environmental conditions cause the temperature of the DC/
DC’s to rise above the Operating Temperature Range up to the shutdown tem-
perature, an on-board electronic temperature sensor will power down the unit.
When the temperature decreases below the turn-on threshold, the converter
will automatically restart. There is a small amount of hysteresis to prevent
rapid on/off cycling. CAUTION: If you operate too close to the thermal limits, the
converter may shut down suddenly without warning. Be sure to thoroughly test
your application to avoid unplanned thermal shutdown.
Temperature Derating Curves
The graphs in the performance data 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 acceptable under
increasing forced airfl ow measured in Linear Feet per Minute (“LFM”). Note that
these are AVERAGE measurements. The converter will accept brief increases in tem-
perature and/or current or reduced airfl ow as long as the average is not exceeded.
self which is obviously running at higher temperature than the outside air. Also
note that “natural convection” is defi ned as very low fl ow rates which are not
using fan-forced airfl ow. Depending on the application, “natural convection” is
usually about 30-65 LFM but is not equal to still air (0 LFM).
cycle wind tunnel with calibrated airfl ow. We use both thermocouples and an
infrared camera system to observe thermal performance. As a practical matter,
it is quite diffi cult to insert an anemometer to precisely measure airfl ow in
most applications. Sometimes it is possible to estimate the effective airfl ow if
you thoroughly understand the enclosure geometry, entry/exit orifi ce areas and
the fan fl owrate specifi cations.
Note that the temperatures are of the ambient airfl ow, not the converter it-
Murata Power Solutions makes Characterization measurements in a closed
+OUTPUT
−OUTPUT
Figure 3. Measuring Output Ripple and Noise (PARD)
C1 = 1μF CERAMIC
C2 = 10μF LOW ES
LOAD 2-3 INCHES (51-76mm) FROM MODULE
C1
COPPER STRIP
COPPER STRIP
C2
SCOPE
www.murata-ps.com
R
LOAD
an unplanned Over Temperature shut down. Also, these graphs are all collected
near Sea Level altitude. Be sure to reduce the derating for higher altitude.
Output Overvoltage Protection (OVP)
This converter monitors its output voltage for an over-voltage condition using
an on-board electronic comparator. The signal is optically coupled to the pri-
mary side PWM controller. If the output exceeds OVP limits, the sensing circuit
will power down the unit, and the output voltage will decrease. After a time-out
period, the PWM will automatically attempt to restart, causing the output volt-
age to ramp up to its rated value. It is not necessary to power down and reset
the converter for this automatic OVP-recovery restart.
levels, the OVP circuitry will initiate another shutdown cycle. This on/off cycling
is referred to as “hiccup” mode.
Output Fusing
The converter is extensively protected against current, voltage and temperature
extremes. However, your application circuit may need additional protection. In the
extremely unlikely event of output circuit failure, excessive voltage could be applied
to your circuit. Consider using an appropriate external protection.
Output Current Limiting
As soon as the output current increases to approximately its overcurrent limit,
the DC/DC converter will enter a current-limiting mode. The output voltage will
decrease proportionally with increases in output current, thereby maintaining a
somewhat constant power output. This is commonly referred to as power limiting.
below the rated tolerance. See the Performance/Functional Specifi cations.
Note particularly that the output current may briefl y rise above its rated value.
This enhances reliability and continued operation of your application. If the
output current is too high, the converter will enter the short circuit condition.
Output Short Circuit Condition
When a converter is in current-limit mode, the output voltage will drop as
the output current demand increases. If the output voltage drops too low, the
magnetically coupled voltage used to develop PWM bias voltage will also drop,
thereby shutting down the PWM controller. Following a time-out period, the
PWM will restart, causing the output voltage to begin rising to its appropriate
value. If the short-circuit condition persists, another shutdown cycle will initi-
ate. This on/off cycling is called “hiccup mode.” The hiccup cycling reduces the
average output current, thereby preventing excessive internal temperatures.
Trimming the Output Voltage
The Trim input to the converter allows the user to adjust the output voltage over
the rated trim range (please refer to the Specifi cations). In the trim equations
and circuit diagrams that follow, trim adjustments use a single fi xed resistor
connected between the Trim input and either Vout pin. Trimming resistors should
have a low temperature coeffi cient (±100 ppm/°C or less) and be mounted close
to the converter. Keep leads short. If the trim function is not used, leave the trim
unconnected. With no trim, the converter will exhibit its specifi ed output voltage
accuracy.
CAUTION: If you exceed these Derating guidelines, the converter may have
If the fault condition persists and the output voltage climbs to excessive
Current limiting inception is defi ned as the point at which full power falls
There are two CAUTIONs to observe for the Trim input:
Single Output Isolated 25-Watt DC/DC Converters
07 Apr 2011
UEI25 Series
MDC_UEI25W.A03 Page 20 of 23
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