DSP56011 View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

Manufacturer

DSP56011

24-BIT DVD DIGITAL SIGNAL PROCESSOR

Motorola => Freescale 

SECTION 4

DESIGN CONSIDERATIONS Y THERMAL DESIGN CONSIDERATIONS

An estimation of the chip junction temperature, TJ, in °C can be obtained from the

R equation:

Equation 1: TJ = TA + (PD × RθJA)

A Where:

TA = ambient temperature ˚C

I N RθJA = package junction-to-ambient thermal resistance ˚C/W

PD = power dissipation in package

Historically, thermal resistance has been expressed as the sum of a junction-to-case

thermal resistance and a case-to-ambient thermal resistance:

I M Equation 2: RθJA = RθJC + RθCA

Where:

RθJA = package junction-to-ambient thermal resistance ˚C/W

L RθJC = package junction-to-case thermal resistance ˚C/W

RθCA = package case-to-ambient thermal resistance ˚C/W

ERθJC is device-related and cannot be influenced by the user. The user controls the

thermal environment to change the case-to-ambient thermal resistance, RθCA. For

example, the user can change the air flow around the device, add a heat sink, change

Rthe mounting arrangement on the printed circuit board, or otherwise change the

Pthermal dissipation capability of the area surrounding the device on a printed circuit

board. This model is most useful for ceramic packages with heat sinks; some 90% of

the heat flow is dissipated through the case to the heat sink and out to the ambient

environment. For ceramic packages, in situations where the heat flow is split between

a path to the case and an alternate path through the printed circuit board, analysis of

the device thermal performance may need the additional modeling capability of a

system level thermal simulation tool.

Preliminary Information

MOTOROLA

DSP56011 Technical Data Sheet, Rev. 1

4-1

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