AX2000-1CS896 datasheet(20/226 Pages) ACTEL

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Axcelerator Family FPGAs

2- 6

v2.7

Thermal Characteristics

Introduction

The temperature variable in Actel’s Designer software refers to the junction temperature, not the ambient

temperature. This is an important distinction because dynamic and static power consumption cause the chip junction

temperature to be higher than the ambient temperature. EQ 2-1 can be used to calculate junction temperature.

TJ = Junction Temperature = ΔT + Ta

EQ 2-1

Where:

ΔT = θ

ja * P

EQ 2-2

Where:

Package Thermal Characteristics

The device junction-to-case thermal characteristic is

jc, and the junction-to-ambient air characteristic is θja. The

thermal characteristics for

ja are shown with two different air flow rates. θjc values are provided for reference. The

absolute maximum junction temperature is 125

°C.

The maximum power dissipation allowed for commercial- and industrial-grade devices is a function of θja. A sample

calculation of the absolute maximum power dissipation allowed for an 896-pin FBGA package at commercial

temperature and still air is as follows:

The maximum power dissipation allowed for Military temperature and Mil-Std 883B devices is specified as a function

jc.

Ta = Ambient Temperature

ΔT = Temperature gradient between junction

(silicon) and ambient

P= Power

= Junction to ambient of package.

ja numbers

are located under Table 2-6 on page 2-6.

Table 2-6 • Package Thermal Characteristics

Package Type

Pin Count

ja Still Air

ja 1.0m/s

ja 2.5m/s

Units

Chip Scale Package (CSP)

180

N/A

57.8

51.0

°C/W

Plastic Quad Flat Pack (PQFP)

208

8.0

23.5

20.9

°C/W

Plastic Ball Grid Array (PBGA)

729

2.2

13.7

10.6

9.6

°C/W

Fine Pitch Ball Grid Array (FBGA)

256

3.0

26.6

22.8

21.5

°C/W

Fine Pitch Ball Grid Array (FBGA)

324

3.0

25.8

22.1

20.9

°C/W

Fine Pitch Ball Grid Array (FBGA)

484

3.2

20.5

17.0

15.9

°C/W

Fine Pitch Ball Grid Array (FBGA)

676

3.2

16.4

13.0

12.0

°C/W

Fine Pitch Ball Grid Array (FBGA)

896

2.4

13.6

10.4

9.4

°C/W

Fine Pitch Ball Grid Array (FBGA)

1152

1.8

12.0

8.9

7.9

°C/W

Ceramic Quad Flat Pack (CQFP)1

208

2.0

19.8

18.0

°C/W

Ceramic Quad Flat Pack (CQFP)1

352

2.0

17.9

16.1

14.7

°C/W

Ceramic Column Grid Array (CCGA)2

624

6.5

8.9

8.5

°C/W

Notes:

θjc for the 208-pin and 352-pin CQFP refers to the thermal resistance between the junction and the bottom of the package.

θjc for the 624-pin CCGA refers to the thermal resistance between the junction and the top surface of the package. Thermal

resistance from junction to board (

jb) for CCGA 624 package is 3.4°C/W.

Maximum Power Allowed

Max. junction temp. (

°C) Max. ambient temp. (°C)

–

ja(°C/W)

---------------------------------------------------------------------------------------------------------------------------------------

125

°C70°C

–

13.6

°C/W

------------------------------------

4.04 W

AX2000-1CS896 Datasheet(PDF) 20 Page - Actel Corporation

AX2000-1CS896 Datasheet(HTML) 20 Page - Actel Corporation

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