MMPF0100Z datasheet(120/128 Pages) NXP

120 / 128 page

120

NXP Semiconductors

PF0100Z

TYPICAL APPLICATIONS

7.3.2

Estimation of junction temperature

An estimation of the chip junction temperature TJ can be obtained from the equation:

TJ = TA + (RθJA x PD)

with:

TA = Ambient temperature for the package in °C

RθJA = Junction to ambient thermal resistance in °C/W

PD = Power dissipation in the package in W

The junction to ambient thermal resistance is an industry standard value provideing a quick and easy estimation of thermal performance.

Unfortunately, there are two values in common usage: the value determined on a single layer board RθJA and the value obtained on a four

layer board RθJMA. Actual application PCBs show a performance close to the simulated four layer board value although this may be

somewhat degraded in case of significant power dissipated by other components placed close to the device.

At a known board temperature, the junction temperature TJ is estimated using the following equation

TJ = TB + (RθJB x PD) with

TB = Board temperature at the package perimeter in °C

RθJB = Junction to board thermal resistance in °C/W

PD = Power dissipation in the package in W

When the heat loss from the package case to the air can be ignored, acceptable predictions of junction temperature can be made.

See 6 Functional block requirements and behaviors, page 17 for more details on thermal management.

MMPF0100Z Datasheet(PDF) 120 Page - NXP Semiconductors