TS68C429AMFBSLASHC datasheet(9/43 Pages) ATMEL

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TS68C429A

2120A–HIREL–08/02

Power Considerations

The average chip-junction temperature, T

J, in °C can be obtained from:

J = TA + (PD ⋅ θJA)(1)

A = Ambient Temperature, °C

JA = Package Thermal Resistance, Junction-to-Ambient, °C/W

D = PINT + PI/O

INT = ICC x VCC, Watts—Chip Internal Power

I/O = Power Dissipation on Input and Output Pins—User Determined

For most applications P

I/O < PINT and can be neglected.

An approximate relationship between P

D and TJ (if PI/O is neglected) is:

D = K: (TJ + 273)

(2)

Solving equations (1) and (2) for K gives:

K = P

D ⋅ (TA + 273) + θJA ⋅ PD

(3)

where K is a constant pertaining to the particular part K can be determined from equa-

tion (3) by measuring P

D (at equilibrium) for a known TA. Using this value of K, the

values of P

D and TJ can be obtained by solving equations (1) and (2) iteratively for any

value of T

The total thermal resistance of a package (

JA) can be separated into two components,

JC and θCA, representing the barrier to heat flow from the semiconductor junction to the

package (case), surface (

JC) and from the case to the outside ambient (θCA). These

terms are related by the equation:

JA = θJC + θCA

(4)

JC is device related and cannot be influenced by the user. However, θCA is user depen-

dent and can be minimized by such thermal management techniques as heat sinks,

ambient air cooling and thermal convection. Thus, good thermal management on the

part of the user can significantly reduce

CA so that θJA approximately equals θJC. Substi-

tution of

JC for θJA in equation (1) will result in a lower semiconductor junction

temperature.

Mechanical and

Environment

The microcircuits shall meet all mechanical environmental requirements of either MIL-

STD-883 for class B devices or DESC devices.

Marking

The document where are defined the marking are identified in the related reference doc-

uments. Each microcircuit are legibly and permanently marked with the following

information as minimum:

•Atmel logo

•

Manufacturer’s part number

•

Class B identification

•

Date-code of inspection lot

•

ESD identifier if available

•

Country of manufacturing

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