A42MX16-PQ208A Datasheet, PDF (19/78 Pages) Actel Corporation – 40MX and 42MX Automotive FPGA Families

40MX and 42MX Automotive FPGA Families
Junction Temperature
The temperature variable in the Designer software refers
to the junction temperature, not the ambient
temperature. This is an important distinction because the
heat generated from dynamic power consumption is
usually hotter than the ambient temperature. EQ 1-3 can
be used to calculate junction temperature.
Junction Temperature = ∆T + T_a (1)
EQ 1-3
Where:
T_a = Ambient Temperature
∆T = Temperature gradient between junction (silicon)
and ambient
∆T = θ_ja * P
P = Power
θ_ja = Junction to ambient of package. θ_ja numbers are
located in the "Package Thermal Characteristics" section.
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 θ_ja are shown with two
different air flow rates.
Maximum junction temperature is 150°C.
A sample calculation of the absolute maximum power
dissipation allowed for a PQFP 160-pin package at
automotive temperature is as follows:
M------a---x---.---j-u----n---c---t--i-o---n-----t--e---m-----p----.-_{θ--(--°j-a-C----)-(-°-–--C---M-/--W--a---)x---.---a---u----t--o---m-----o---t--i--v--e-------t--e---m-----p---.}
=
-1---5---0----°--C------–----1----2---5---°---C--
26.2°C/W
=
0.95W
Table 1-6 • Package Thermal Characteristics
Plastic Packages
Plastic Quad Flat Pack
Plastic Quad Flat Pack
Plastic Quad Flat Pack
Plastic Quad Flat Pack
Plastic Leaded Chip Carrier
Plastic Leaded Chip Carrier
Thin Plastic Quad Flat Pack
Very Thin Plastic Quad Flat Pack
Very Thin Plastic Quad Flat Pack
Pin Count
100
θ_jc
12.0
160
10.0
208
8.0
240
8.5
68
13.0
84
12.0
176
11.0
80
12.0
100
10.0
Still Air
27.8
26.2
26.1
25.6
25.0
22.5
24.7
38.2
35.3
θ_ja
1.0 m/s
200 ft./min.
2.5 m/s
500 ft./min.
23.4
21.2
22.8
21.1
22.5
20.8
22.3
20.8
21.0
19.4
18.9
17.6
19.9
18.0
31.9
29.4
29.4
27.1
Units
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
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