TS615

Printed Circuit Board Layout Considerations

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6 Printed Circuit Board Layout Considerations

In the ADSL frequency rangey, printed circuit board parasites can affect the closed-loop performance.

The use of a proper ground plane on both sides of the PCB is necessary to provide low inductance and a

low resistance common return. The most important factors affecting gain flatness and bandwidth are

stray capacitance at the output and inverting input. To minimize capacitance, the space between signal

lines and ground plane should be maximized. Feedback component connections must be as short as

possible in order to decrease the associated inductance which affects high-frequency gain errors. It is

very important to choose the smallest possible external components—for example, surface mounted

devices (SMD)—in order to minimize the size of all DC and AC connections.

6.1 Thermal information

The TS615 is housed in an exposed-pad plastic package. As described in Figure 55, this package has a

lead frame upon which the dice is mounted. This lead frame is exposed as a thermal pad on the

underside of the package. The thermal contact is direct with the dice. This thermal path provides an

excellent thermal performance.

The thermal pad is electrically isolated from all pins in the package. It must be soldered to a copper area

of the PCB underneath the package. Through these thermal paths within this copper area, heat can be

Figure 55. Exposed-pad package

Figure 56. Evaluation board

1

Cross Section View

Bottom View

Side View

DICE

1

Cross Section View

Bottom View

Side View

DICE