UHE-1.2/10000-D12-C Murata Power Solutions Inc, UHE-1.2/10000-D12-C Datasheet - Page 13

• Manufacturer Part Number: UHE-1.2/10000-D12-C
• Description: DC/DC TH 10A 12-1.2V XHE
• Manufacturer: Murata Power Solutions Inc
• Series: UHEr

Specifications of UHE-1.2/10000-D12-C

• Product: Isolated
• Output Power: 12 W
• Input Voltage Range: 9 V to 18 V
• Input Voltage (nominal): 12 V
• Number Of Outputs: 1
• Output Voltage (channel 1): 1.2 V
• Output Current (channel 1): 10 A
• Isolation Voltage: 1.5 KV
• Package / Case Size: 1.6 in X 2 in
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

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 imped-
ance can affect system stability. In Figure 2, C
dc voltage bus. Your specifi c system confi guration may necessitate additional
considerations.
random deviations or PARD) may be reduced below specifi ed limits using fi lter-
ing techniques, the simplest of which is the installation of additional external
output capacitors. These output caps function as true fi lter elements and
should be selected for bulk capacitance, low ESR and appropriate 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 also be taken carefully into consideration.
of line voltage and source impedance, as well as particular load and layout
conditions. Our Applications Engineers can recommend potential solutions and
discuss the possibility of our modifying a given device's internal fi ltering to
meet your specifi c requirements. Contact our Applications Engineering Group
for additional details.
between the power supply and its load. In order to minimize measurement errors,
scope measurements should be made using BNC connectors, or the probe
ground should be less than ½ inch and soldered directly to the fi xture.
In critical applications, output ripple/noise (also referred to as periodic and
The most effective combination of external I/O capacitors will be a function
In Figure 3, the two copper strips simulate real-world pcb impedances
V
OSCILLOSCOPE
IN
–
+
C
C
L
+OUTPUT
–OUTPUT
TO
BUS
+SENSE
IN
BUS
–SENSE
= 33μF, ESR < 700m
Figure 3. Measuring Output Ripple/Noise (PARD)
= 12μH
= 220μF, ESR < 100m
Figure 2. Measuring Input Ripple Current
C
BUS
C1 = 0.47μF CERAMIC
C2 = NA
LOAD 2-3 INCHES (51-76mm) FROM MODULE
L
BUS
C1
COPPER STRIP
COPPER STRIP
@ 100kHz
CURRENT
@ 100kHz
PROBE
C
IN
C2
BUS
and L
SCOPE
+INPUT
–INPUT
BUS
simulate a typical
www.murata-ps.com
R
LOAD
Floating Outputs
Since these are isolated DC/DC converters, their outputs are "fl oating" with
respect to their input. Designers will normally use the –Output (pin 7) as the
ground/return of the load circuit. You can, however, use the +Output (pin 6) as
ground/return to effectively reverse the output polarity.
Minimum Output Loading Requirements
UHE converters employ a synchronous-rectifi er design topology and all models
regulate within spec and are stable under no-load to full load conditions.
Operation under no-load conditions however might slightly increase the output
ripple and noise.
Thermal Shutdown
These UHE converters are equipped with thermal-shutdown circuitry. If envi-
ronmental conditions cause the internal temperature of the DC/DC converter to
rise above the designed operating temperature, a precision temperature sensor
will power down the unit. When the internal temperature decreases below the
threshold of the temperature sensor, the unit will self start. See Performance/
Functional Specifi cations.
Output Overvoltage Protection
UHE output voltages are monitored for an overvoltage condition via magnetic
feedback. The signal is coupled to the primary side and if the output voltage
rises to a level which could be damaging to the load, the sensing circuitry will
power down the PWM controller causing the output voltages to decrease. Fol-
lowing a time-out period the PWM will restart, causing the output voltages to
ramp to their appropriate values. If the fault condition persists, and the output
voltages again climb to excessive levels, the overvoltage circuitry will initiate
another shutdown cycle. This on/off cycling is referred to as "hiccup" mode.
comparator which is optically coupled to the primary side thus allowing tighter
and more precise control.
Current Limiting
As soon as the output current increases to 10% to 50% above its rated value,
the DC/DC converter will go into a current-limiting mode. In this condition, the
output voltage will decrease proportionately with increases in output current,
thereby maintaining somewhat constant power dissipation. This is commonly
referred to as power limiting. Current limit inception is defi ned as the point at
which the full-power output voltage falls below the specifi ed tolerance. See
Performance/Functional Specifi cations. If the load current, being drawn from
the converter, is signifi cant enough, the unit will go into a short circuit condition
as specifi ed under “Performance.”
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 primary side voltages will also
drop, thereby shutting down the PWM controller. Following a time-out period,
the PWM will restart causing the output voltages to begin ramping to their
appropriate values. If the short-circuit condition persists, another shutdown
cycle will be initiated. This on/off cycling is referred to as “hiccup” mode. The
hiccup cycling reduces the average output current, thereby preventing internal
temperatures from rising to excessive levels. The UHE is capable of enduring
an indefi nite short circuit output condition.
Contact MPS for an optional output overvoltage monitor circuit using a
2-10 Amp, 12-30 Watt DC/DC Converters
28 Mar 2011 MDC_UHE_12-30W Series.B16 Page 13 of 16
Isolated, High Effi ciency, 1.6" × 2"
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UHE Series