MMPF0200 datasheet(105/114 Pages) NXP

105 / 114 page

NXP Semiconductors

105

PF0200

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 that provides 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 Functional block requirements and behaviors for more details on thermal management.

MMPF0200 Datasheet(PDF) 105 Page - NXP Semiconductors