Data Sheet

ADCA3280

APPLICATIONS INFORMATION

analog.com

Rev. 0 | 13 of 18

THERMAL CONSIDERATIONS

The ADCA3280 is packaged in an industry-standard 9-terminal, 9

mm x 8 mm LGA_CAV package. The thermal resistance from θJC

is 3.2°C/W at 24 V, where the case is defined by the exposed pad

on the bottom of the package. For the best thermal performance,

it is recommended to add as many thermal vias as possible under

the exposed pad of the LGA_CAV. Thermal transfer is maximized

when the amount of copper under the exposed pad is maximized.

A solid copper slug captured in the PCB can also be used in

place of vias to provide additional thermal benefits; however, this

slug is not required for typical operation. The array of vias under

the ADCA3280 must interface to an external heat sink such as a

pedestal on the system chassis.

SOLDERING INFORMATION AND

RECOMMENDED PCB LAND PATTERN

Figure 22 shows the recommended land pattern for the ADCA3280.

To minimize thermal impedance, the exposed pad on the 9 mm ×

8 mm LGA_CAV is soldered to a ground plane. To improve thermal

dissipation, 188 thermal vias are arranged in an array under the

exposed pad. The array consists of alternating rows of 13 vias and

12 vias, maximizing the number of vias within the area. The area

under the exposed pad is also tied to ground on the bottom layer

of the PCB. If multiple ground layers exist, tie these layers together

by the vias. The external layer of the PCB must be a minimum of 1

oz. copper. The minimum average plated hole wall thickness of the

vias must not be less than 0.001 inches. Additional copper and vias

extending beyond the top and bottom of the ADCA3280 package

can provide a small additional thermal benefit.

Figure 23 shows the recommended solder dispense pattern for

the ADCA3280. The pads are fully covered with solder, while the

thermal pad has 40% coverage broken into squares to minimize

solder voiding.

For further information on optimizing the thermal performance while

using the ADCA3280, refer to the AN-1604 Application Note, Ther-

mal Management Calculations for RF Amplifiers in LFCSP and

Flange Packages.

Figure 22. Recommended PCB Layout (Dimensions Shown in Millimeters)