A3PN015-QNG68 Datasheet, PDF (19/114 Pages) Microsemi Corporation – ProASIC3 nano Flash FPGAs

ProASIC3 nano Flash FPGAs
Thermal Characteristics
Introduction
The temperature variable in the 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 to be higher than the ambient temperature.
EQ 1 can be used to calculate junction temperature.
T_J = Junction Temperature = T + T_A
where:
T_A = Ambient Temperature
T = Temperature gradient between junction (silicon) and ambient T = _ja * P
_ja = Junction-to-ambient of the package. _ja numbers are located in Table 2-5.
P = Power dissipation
EQ 1
Package Thermal Characteristics
The device junction-to-case thermal resistivity is _jc and the junction-to-ambient air thermal resistivity is
_ja. The thermal characteristics for _ja are shown for two air flow rates. The absolute maximum junction
temperature is 100°C. EQ 2 shows a sample calculation of the absolute maximum power dissipation
allowed for a 484-pin FBGA package at commercial temperature and in still air.
Maximum Power Allowed = ^M-----^a----^x---^.---^j--^u---ⁿ---^c---^t--ⁱ-^o----ⁿ-----^t-^e----^m-----^p---^.-----⁽-_-^--_j-^C_a---₍-⁾--_--–_C----^M-_/-_W---^a---₎-^x---^.---^a---^m-----^b----ⁱ-^e---ⁿ----^t---^t--^e---^m-----^p---^.----⁽--^---^C----⁾- = ^{1----0--2-0--0--}--.-C5----_-^–--C---7-/--W0----^---C-- = 1.463 W^·
EQ 2
Table 2-5 • Package Thermal Resistivities
Package Type
Quad Flat No Lead (QFN)
Device Pin Count
All devices
48
_jc
TBD
_ja
Still Air 200 ft./min.
TBD
TBD
500 ft./min. Units
TBD
C/W
68
TBD TBD
TBD
TBD
C/W
100
TBD TBD
TBD
TBD
C/W
Very Thin Quad Flat Pack (VQFP) All devices 100
10.0 35.3
29.4
27.1
C/W
Temperature and Voltage Derating Factors
Table 2-6 • Temperature and Voltage Derating Factors for Timing Delays
(normalized to T_J = 70°C, VCC = 1.425 V)
Junction Temperature (°C)
Array Voltage VCC (V)
–40°C
–20°C
0°C
25°C
70°C
1.425
0.968
0.973
0.979
0.991
1.000
1.500
0.888
0.894
0.899
0.910
0.919
1.575
0.836
0.841
0.845
0.856
0.864
85°C
1.006
0.924
0.870
100°C
1.013
0.930
0.875
Revision 11
2-5