THS6002_16 Datasheet, PDF (31/46 Pages) Texas Instruments – DUAL DIFFERENTIAL LINE DRIVERS AND RECEIVERS

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THS6002
DUAL DIFFERENTIAL LINE DRIVERS AND RECEIVERS
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SLOS202E− JANUARY 1998− REVISED MARCH 2007
APPLICATION INFORMATION
PCB design considerations (continued)
D Proper power supply decoupling − Use a minimum of a 6.8-µF tantalum capacitor in parallel with a 0.1-µF
ceramic capacitor on each supply terminal. It may be possible to share the tantalum among several
amplifiers depending on the application, but a 0.1-µF ceramic capacitor should always be used on the
supply terminal of every amplifier. In addition, the 0.1-µF capacitor should be placed as close as possible
to the supply terminal. As this distance increases, the inductance in the connecting etch makes the capacitor
less effective. The designer should strive for distances of less than 0.1 inches (2,54 mm) between the device
power terminal and the ceramic capacitors.
Because of its power dissipation, proper thermal management of the THS6002 is required. Although there are
many ways to properly heatsink this device, the following steps illustrate one recommended approach for a
multilayer PCB with an internal ground plane.
1. Prepare the PCB with a top side etch pattern as shown in Figure 57. There should be etch for the leads as
well as etch for the thermal pad.
2. Place five holes in the area of the thermal pad. These holes should be 13 mils (0,33 mm) in diameter. They
are kept small so that solder wicking through the holes is not a problem during reflow.
3. Place four more holes under the package, but outside the thermal pad area. These holes are 25 mils
(0,635 mm) in diameter. They may be larger because they are not in the area to be soldered so that wicking
is not a problem.
4. Connect all nine holes, the five within the thermal pad area and the four outside the pad area, to the internal
ground plane.
5. 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 THS6002 package should make their connection to the internal ground plane with a
complete connection around the entire circumference of the plated through hole.
6. The top-side solder mask should leave exposed the terminals of the package and the thermal pad area with
its five holes. The four larger holes outside the thermal pad area, but still under the package, should be
covered with solder mask.
7. Apply solder paste to the exposed thermal pad area and all of the operational amplifier terminals.
8. With these preparatory steps in place, the THS6002 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.
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