40MX and 42MX FPGA Families
1- 26
R e v i sio n 1 1
Package Thermal Characteristics
The device junction-to-case thermal characteristic is
θ
jc, and the junction-to-ambient air characteristic is
θ
ja. The thermal characteristics for θja are shown with two different air flow rates.
The maximum junction temperature is 150
°C.
Maximum power dissipation for commercial- and industrial-grade devices is a function of
θ
ja.
A sample calculation of the absolute maximum power dissipation allowed for a TQ176 package at
commercial temperature and still air is given in
EQ 2.EQ 2
The maximum power dissipation for military-grade devices is a function of
θ
jc. A sample calculation of the
absolute maximum power dissipation allowed for CQFP 208-pin package at military temperature and still
EQ 3
Maximum Power Allowed
Max. junction temp. (
°C) Max. ambient temp. (°C)
–
θ
ja(°C/W)
------------------------------------------------------------------------------------------------------------------------------------------
150
°C70°C
–
28
°C/W
-------------------------------------
2.86 W
=
Maximum Power Allowed
Max. junction temp. (
°C) Max. ambient temp. (°C)
–
θ
jc(°C/W)
------------------------------------------------------------------------------------------------------------------------------------------
150
°C125°C
–
6.3
°C/W
----------------------------------------
3.97 W
=
Table 1-21 Package Thermal Characteristics
Plastic Packages
Pin Count
θ
jc
θ
ja
Units
Still Air
1.0 m/s
200 ft/min.
2.5 m/s
500 ft/min.
Plastic Quad Flat Pack
100
12.0
27.8
23.4
21.2
°C/W
Plastic Quad Flat Pack
160
10.0
26.2
22.8
21.1
°C/W
Plastic Quad Flat Pack
208
8.0
26.1
22.5
20.8
°C/W
Plastic Quad Flat Pack
240
8.5
25.6
22.3
20.8
°C/W
Plastic Leaded Chip Carrier
44
16.0
20.0
24.5
22.0
°C/W
Plastic Leaded Chip Carrier
68
13.0
25.0
21.0
19.4
°C/W
Plastic Leaded Chip Carrier
84
12.0
22.5
18.9
17.6
°C/W
Thin Plastic Quad Flat Pack
176
11.0
24.7
19.9
18.0
°C/W
Very Thin Plastic Quad Flat Pack
80
12.0
38.2
31.9
29.4
°C/W
Very Thin Plastic Quad Flat Pack
100
10.0
35.3
29.4
27.1
°C/W
Plastic Ball Grid Array
272
3.0
18.3
14.9
13.9
°C/W
Ceramic Packages
Ceramic Quad Flat Pack
208
2.0
22.0
19.8
18.0
°C/W
Ceramic Quad Flat Pack
256
2.0
20.0
16.5
15.0
°C/W