UVQ-12/10-D48P-C Murata Power Solutions Inc, UVQ-12/10-D48P-C Datasheet - Page 18

• Manufacturer Part Number: UVQ-12/10-D48P-C
• Description: DC/DC TH 10A 48-12V Q-Brick
• Manufacturer: Murata Power Solutions Inc
• Series: UVQr

Specifications of UVQ-12/10-D48P-C

• Dc / Dc Converter O/p Type: Single
• No. Of Outputs: 1
• Input Voltage: 36V To 75V
• Power Rating: 120W
• Output Voltage: 12V
• Output Current: 10A
• Approval Bodies: EN / IEC / UL
• Supply Voltage: 48V
• Rohs Compliant: Yes
• Product: Isolated
• Output Power: 120 W
• Input Voltage Range: 36 V ot 75 V
• Input Voltage (nominal): 48 V
• Number Of Outputs: 1
• Output Voltage (channel 1): 12 V
• Output Current (channel 1): 10 A
• Isolation Voltage: 2.25 KV
• Package / Case Size: Quarter Brick
• Lead Free Status / Rohs Status: Details

UVQ Series Aluminum Heatsink
The UVQ series converter baseplate can be attached either to an enclosure
wall or a heatsink to remove heat from internal power dissipation. The discus-
sion below concerns only the heatsink alternative. The UVQ’s are available
with a low-profi le extruded aluminum heatsink kit, models HS-QB25-UVQ,
HS-QB50-UVQ, and HS-QB100-UVQ. This kit includes the heatsink, thermal
mounting pad, screws and mounting hardware. See the assembly diagram
below. Do not overtighten the screws in the tapped holes in the converter. This
kit adds excellent thermal performance without sacrifi cing too much compo-
nent height. See the Mechanical Outline Drawings for assembled dimensions.
If the thermal pad is fi rmly attached, no thermal compound (“thermal grease”)
is required.
When assembling these kits onto the converter, include ALL kit hardware to
assure adequate mechanical capture and proper clearances. Thread relief is
0.090" (2.3mm).
www.cd4power.com
Figure 7. Model UVQ Heatsink Assembly Diagram
®
Low-Profi le, Isolated Quarter-Brick 2.5-40 Amp DC/DC Converters
Thermal Performance
The HS-QB25-UVQ heatsink has a thermal resistance of 12 degrees Celsius
per Watt of internal heat dissipation with “natural convection” airfl ow (no
fans or other mechanical airfl ow) at sea level altitude. This thermal resistance
assumes that the heatsink is fi rmly attached using the supplied thermal pad
and that there is no nearby wall or enclosure surface to inhibit the airfl ow. The
thermal pad adds a negligible series resistance of approximately 0.5°C/Watt
so that the total assembled resistance is 12.5°C/Watt.
Be aware that we need to handle only the internal heat dissipation, not the full
power output of the converter. This internal heat dissipation is related to the
effi ciency as follows:
Effi ciency of course varies with input voltage and the total output power.
Please refer to the Performance Curves.
Since many applications do include fans, here is an approximate equation to
calculate the net thermal resistance:
Where,
RΘ [at airfl ow] is the net thermal resistance (in °C/W) with the amount of
airfl ow available and,
RΘ [natural convection] is the still air total path thermal resistance or in this
case 12.5°C/Watt and,
“Airfl ow in LFM” is the net air movement fl ow rate immediately at the converter.
This equation simplifi es an otherwise complex aerodynamic model but is
a useful starting point. The “Airfl ow Constant” is dependent on the fan and
enclosure geometry. For example, if 200 LFM of airfl ow reduces the effective
natural convection thermal resistance by one half, the airfl ow constant would
be 0.005. There is no practical way to publish a “one size fi ts all” airfl ow
constant because of variations in airfl ow direction, heatsink orientation,
adjacent walls, enclosure geometry, etc. Each application must be determined
empirically and the equation is primarily a way to help understand the cooling
arithmetic.
This equation basically says that small amounts of forced airfl ow are quite
effective removing the heat. But very high airfl ows give diminishing returns.
Conversely, no forced airfl ow causes considerable heat buildup. At zero
airfl ow, cooling occurs only because of natural convection over the heatsink.
Natural convection is often well below 50 LFM, not much of a breeze.
While these equations are useful as a conceptual aid, most users fi nd it very
diffi cult to measure actual airfl ow rates at the converter. Even if you know
the velocity specifi cations of the fan, this does not usually relate directly to
the enclosure geometry. Be sure to use a considerable safety margin doing
thermal analysis. If in doubt, measure the actual heat sink temperature with
a calibrated thermocouple, RTD or thermistor. Safe operation should keep the
heat sink below 100°C.
Power Dissipation [Pd] = Power In – Power Out [1]
Power Out / Power In = Effi ciency [in %] / 100 [2]
Power Dissipation [Pd] = Power In x (1 –Effi ciency%/100) [3]
Power Dissipation [Pd] = Power Out x (1 / (Effi ciency%/100) - 1) [4]
RΘ [at airfl ow] = RΘ [natural convection] / (1 + (Airfl ow in LFM) x
[Airfl ow Constant]) [5]
UVQ Series
UVQ Series
Page 18 of 20