Data Sheet

ADCA3270

Rev. 0 | Page 11 of 14

APPLICATIONS INFORMATION

ADCA3270 TEMPERATURE SENSE MONITOR

The ADCA3270 has an internally mounted, negative temperature

coefficient (NTC) thermistor that, when used as the bottom of a

resistive voltage divider, provides an output voltage that is

LGA_CAV package. When configured as shown in Figure 16,

what is shown in Figure 17.

NTC

ADCA3270

3.3kΩ

5V

REFERENCE

8

Figure 16. Recommended NTC Configuration

95

90

85

80

75

65

70

60

55

50

45

40

35

30

25

20

0.6

0.8

1.0

1.4

1.6

1.8

1.2

2.0

2.2

2.4

THERMAL CONSIDERATIONS

The ADCA3270 is packaged in a thermally efficient, 9-terminal

chip array small outline no lead cavity [LGA_CAV]. The

by the exposed paddle on the bottom of the package. For the

best thermal performance, it is recommended that as many

thermal vias as possible be added under the exposed paddle of

the LGA_CAV package. For optimal performance, it is

recommended that these vias be filled with a paste that has high

thermal conductivity. It is also recommended that the array of

vias under the ADCA3270 interface to an external heat sink

such as a pedestal on the system chassis.

SOLDERING INFORMATION AND RECOMMENDED

PCB LAND PATTERN

Figure 18 shows the recommended land pattern for the

ADCA3270. To minimize thermal impedance, the exposed

paddle on the 9.00 mm × 8.00 mm LGA_CAV is soldered to a

ground plane along with Pin 2, Pin 3, and Pin 6. To improve

thermal dissipation, 188 thermal vias are arranged in an array

under the exposed paddle. The array consists of alternating

rows of 13 vias and 12 vias, maximizing the number of vias

within the area. The area under the paddle 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 2 oz. copper. The minimum

average plated hole wall thickness of the vias must not be less

than 0.001 inch, and it is recommended that the vias be filled

with a conductive paste, such as Tatsuta AE3030, and plated

over. The full recommended PCB footprint design is shown in

Figure 19.

Figure 18. Recommended Land Pattern

For further information on optimizing the thermal performance

while using the ADCA3270, refer to the AN-1604 Application

Note, Thermal Management Calculations for RF Amplifiers in

LFCSP and Flange Packages.