THS3091 Datasheet, PDF (41/45 Pages) Texas Instruments – HIGH-VOLTAGE, LOW-DISTORTION, CURRENT-FEEDBACK OPERATIONAL AMPLIFIERS

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THS3091, THS3095
SLOS423H – SEPTEMBER 2003 – REVISED DECEMBER 2015
10.3 PowerPAD Design Considerations
The THS309x are available in a thermally-enhanced PowerPAD family of packages. These packages are
constructed using a downset leadframe on which the die is mounted [see Figure 83(a) and Figure 83(b)]. This
arrangement results in the lead frame being exposed as a thermal pad on the underside of the package [see
Figure 83(c)]. Because this thermal pad has direct thermal contact with the die, excellent thermal performance
can be achieved by providing a good thermal path away from the thermal pad. Note that devices such as the
THS309x have no electrical connection between the PowerPAD and the die.
The PowerPAD package allows for both assembly and thermal management in one manufacturing operation.
During the surface-mount solder operation (when the leads are being soldered), the thermal pad can also be
soldered to a copper area underneath the package. Through the use of thermal paths within this copper area,
heat can be conducted away from the package into either a ground plane or other heat-dissipating device.
The PowerPAD package represents a breakthrough in combining the small area and ease of assembly of
surface mount with the, heretofore, awkward mechanical methods of heatsinking.
DIE
Side View (a)
DIE
End View (b)
Thermal
Pad
Bottom View (c)
Figure 83. Views of Thermal Enhanced Package
Although there are many ways to properly heatsink the PowerPAD package, the following steps illustrate the
recommended approach.
0.300
(7,62)
0.100
(2,54)
0.035
(0,89)
0.010
(0,254)
0.026
(0,66)
0.060
(1,52)
0.140
(3,56)
0.060
(1,52)
0.030
(0,732)
0.176
(4,47)
0.050
(1,27)
0.010
(0.254)
vias
0.035
(0,89)
0.080
(2,03)
All Units in inches (millimeters)
Figure 84. DDA PowerPAD PCB Etch and via Pattern
10.3.1 PowerPAD Layout Considerations
1. PCB with a top-side etch pattern is shown in Figure 84. There should be etch for the leads as well as etch for
the thermal pad.
2. Place 13 holes in the area of the thermal pad. These holes should be 0.01 inch (0.254 mm) in diameter.
Keep them small so that solder wicking through the holes is not a problem during reflow.
3. Additional vias may be placed anywhere along the thermal plane outside of the thermal pad area. This helps
dissipate the heat generated by the THS309x IC. These additional vias may be larger than the 0.01-inch
(0.254 mm) diameter vias directly under the thermal pad. They can be larger because they are not in the
thermal pad area to be soldered so that wicking is not a problem.
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