ADP172ACBZ-2.1-R7 datasheet(15/17 Pages) AD

15 / 17 page

Data Sheet

ADP172

APPLICATIONS INFORMATION

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Rev. F | 15 of 17

Figure 35. 0 mm2 of PCB Copper, TA = 50°C

In cases where board temperature is known, use the thermal

characterization parameter, ΨJB, to estimate the junction tempera-

ture rise (see Figure 36). Maximum junction temperature (TJ) is

calculated from the board temperature (TB) and power dissipation

(PD) using the following formula:

TJ=TB+ PD×ψJB

(5)

The typical value of ΨJB is 58°C/W for the 4-ball WLCSP package.

Figure 36. TA = 85°C

PRINTED CIRCUIT BOARD LAYOUT

CONSIDERATIONS

Heat dissipation from the package can be improved by increasing

the amount of copper attached to the pins of the ADP172. However,

as can be seen from Table 6, a point of diminishing returns is

eventually reached, beyond which an increase in the copper size

does not yield significant heat dissipation benefits.

Place the input capacitor as close as possible to the VIN and

GND pins. Place the output capacitor as close as possible to the

VOUT and GND pins. Use of 0402 or 0603 size capacitors and

resistors achieves the smallest possible footprint solution for boards

on which area is limited.

Figure 37. Example ADP172 PCB Layout

ADP172ACBZ-2.1-R7 Datasheet(PDF) 15 Page - Analog Devices