NQ16W50SMA16 Datasheet, PDF (11/13 Pages) SynQor Worldwide Headquarters – SMT Surface Mount

Technical Specification
Input: 6.0 - 16.0V
Outputs: 0.75 - 5.0V
Current: 16A
Package: SMT
Thermal Performance (SMA16): While impossible to be
exact, a simplified thermal model for the mounted converter is
detailed below.
Figure I: Thermal Model for NQ16 Surface Mount
• Rt_J-Pcb models the conduction of heat from the converter's
hottest junction to the converter's PCB at large. It is about
3^oC/W for converters running at higher output voltage, and
about 4^oC/W for lower voltage converters.
• Rt_Pcb-Amb models the power dissipation from converter PCB
to the air stream. It ranges from about 15^oC/W at 400LFM to
about 25^oC/W 100LFM.
• Rt_Pcb-Feet expresses the thermal path from the converter's
PCB though its mounting feet; it is about 3^oC/W.
• Rt_spread models the heat spreading on the PCB to which the
converter is mounted and is largely dependent upon the con-
struction and layout of that PCB.
• T_mount is the temperature of that PCB in the greater vicinity of
the converter.
As is evident, the values for Rt_spread and T_mount will have
great effect upon the thermal operation of the converter. With
Rt_Pcb-Amb being 5 to 8 times as large as Rt_Pcb-Feet, in most
applications these converters will be predominantly cooled via
thermal conduction through their feet. Airflow and T_Amb will
have only a minimal cooling effect.
• Rt_spread should be minimized. Attach the converter to large
copper planes, on multiple layers, with multiple vias near the
mounting feet.
• T_mount should also be minimized. Place the converter far
enough away from other sources of heat on the PCB so that it
is as cool as practical.
• If operation near derating limits is even suspected, thermal per-
formance should be verified with the unit mounted in its intend-
ed manner and powered in circuit with all neighboring circuit-
ry active. Attach a thermocouple to the converter's hotspot as
shown in Figures 4, 6, and 8 in the Performance Curves sec-
tion.
SURFACE MOUNT INFORMATION
PCB Layout Considerations: SynQor recommends that the
customer use a non-solder mask defined pad design. The mini-
mum recommended pad size is 0.074" x 0.122" (1.88mm x
3.1mm) and the maximum pad size is 0.095" x 0.140" (2.41mm
x 3.56mm), see the mechanical diagram on page 2.
Interconnection to internal power planes is typically required.
This can be accomplished by placing a number of vias between
the SMT pad and the relevant plane. The number and location
of the vias should be determined based on electrical resistance,
current and thermal requirements. "Via-in-pad" design should be
avoided in the SMT pads. Solder mask should be used to elimi-
nate solder wicking into the vias.
Pick and Place: The NiQor surface mount modules are
designed for automated assembly using standard SMT pick and
place equipment. The modules have a centrally located inductor
component with a flat surface area to be used for component
pick-up. The units use open frame construction and have a low
mass that is within the capability of standard pick and place
equipment. Those modules however have a larger mass than
most conventional SMT components and so variables such as
nozzle size, tip style, handling speed, and placement pressure
should be optimized for best results. A conformal tipped place-
ment nozzle design is recommended. Coplanarity of better than
0.004" (0.1mm) is achieved through the SMT NiQor's terminal
design.
Product # NQ16W50SMA16
Phone [phone]
www.synqor.com
Doc.# 005-2NS12WE Rev. A 11/26/07
Page 11