THS6022 Datasheet, PDF (30/38 Pages) Texas Instruments – 250-mA DUAL DIFFERENTIAL LINE DRIVER

THS6022
250-mA DUAL DIFFERENTIAL LINE DRIVER
SLOS225C – SEPTEMBER 1998 – REVISED JANUARY 2000
APPLICATION INFORMATION
PCB design considerations (continued)
1. Place 6 holes in the area of the thermal pad. These holes should be 13 mils in diameter. They are kept small
so that solder wicking through the holes is not a problem during reflow.
2. Additional vias may be placed anywhere along the thermal plane outside of the thermal pad area. This will
help dissipate the heat generated from the THS6022. These additional vias may be larger than the 13 mil
diameter vias directly under the thermal pad. They can be larger because they are not in the thermal-pad
area to be soldered, therefore, wicking is generally not a problem.
3. Connect all holes to the internal ground plane.
4. When connecting these holes to the ground plane, do not use the typical web or spoke via connection
methodology. Web connections have a high thermal resistance connection that is useful for slowing the heat
transfer during soldering operations. This makes the soldering of vias that have plane connections easier.
However, in this application, low thermal resistance is desired for the most efficient heat transfer. Therefore,
the holes under the THS6022 package should make their connection to the internal ground plane with a
complete connection around the entire circumference of the plated through hole.
5. The top-side solder mask should leave exposed the terminals of the package and the thermal pad area with
its 6 holes. The bottom-side solder mask should cover the 6 holes of the thermal pad area. This eliminates
the solder from being pulled away from the thermal pad area during the reflow process.
6. Apply solder paste to the exposed thermal pad area and all of the operational amplifier terminals.
7. With these preparatory steps in place, the THS6022 is simply placed in position and run through the solder
reflow operation as any standard surface-mount component. This results in a part that is properly installed.
The actual thermal performance achieved with the THS6022 in its PowerPAD package depends on the
application. In the example above, if the size of the internal ground plane is approximately 3 inches × 3 inches,
+ ǒ Ǔ ^{then the expected thermal coefficient, θJA, is about 37.5°C/W. For a given θJA, the maximum power dissipation}
is shown in Figure 60 and is calculated by the following formula:
PD
TMAX –TA
q_JA
Where:
P_D = Maximum power dissipation of THS6022 (watts)
T_MAX = Absolute maximum junction temperature (150°C)
T_A = Free-ambient air temperature (°C)
θ_JA = θ_JC + θ_CA
θ_JC = Thermal coefficient from junction to case ( 2.07°C/W)
θ_CA = Thermal coefficient from case to ambient air
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