ADP2370ACPZ-3.0-R7 datasheet(30/32 Pages) AD

30 / 32 page

ADP2370/ADP2371

Data Sheet

Rev. A | Page 30 of 32

0.2

0.6

0.4

0.8

1.0

TOTAL POWER DISSIPATION (W)

6400mm2

500mm2

100mm2

TJ MAX

105

115

125

135

Figure 89. Junction Temperature vs. Power Dissipation, TA = 85°C

In cases where the board temperature is known, use the thermal

characterization parameter, ΨJB, to estimate the junction temper-

ature rise. Maximum junction temperature (TJ) is calculated

from the board temperature (TB) and power dissipation (PD)

using the formula:

TJ = TB + (PD × ΨJB)

(5)

The typical ΨJB value for the 8-lead, 3 mm × 3 mm LFCSP is

22.2°C/W.

100

120

140

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

TOTAL POWER DISSIPATION (W)

25°C

50°C

65°C

85°C

TJ MAX

Figure 90. Junction Temperature vs. Power Dissipation,

Different Board Temperatures

PCB LAYOUT CONSIDERATIONS

Improve heat dissipation from the package by increasing

the amount of copper attached to the pins of the ADP2370/

ADP2371. However, as listed in Table 8, a point of diminishing

returns is eventually reached, beyond which an increase in the

copper size does not yield significant heat dissipation benefits.

Poor layout can affect the ADP2370/ADP2371 buck performance

causing electromagnetic interference (EMI), poor electromagnetic

compatibility (EMC) performance, ground bounce, and voltage

losses; thus, regulation and stability can be affected. Implement

a good PCB layout to ensure optimum performance by applying

the following rules:

•

Place the inductor, input capacitor, and output capacitor

close to the IC using short tracks. These components carry

high switching frequencies and long, large tracks act like

antennas.

•

Route the output voltage path away from the inductor and

SW node to minimize noise and magnetic interference.

•

Use a ground plane with several vias connected to the

component-side ground to reduce noise interference on

sensitive circuit nodes.

•

Use of 0402-size or 0603-size capacitors achieves the smallest

possible footprint solution on boards where area is limited.

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