A3PE1500-FGG484 Datasheet, PDF (19/162 Pages) Microsemi Corporation – ProASIC3E Flash Family FPGAs with Optional Soft ARM Support

ProASIC3E Flash Family FPGAs
Thermal Characteristics
Introduction
The temperature variable in 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 110°C. EQ 2 shows a sample calculation of the absolute maximum power dissipation
allowed for an 896-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--1---10---3-^--.-C6---_--–-C----7/--W-0---^---C-- = 5.88 W
EQ 2
Table 2-5 • Package Thermal Resistivities
Package Type
Plastic Quad Flat Package (PQFP)
_ja
Pin Count
_jc
Still Air 200 ft./min. 500 ft./min. Units
208
8.0
26.1
22.5
20.8
C/W
Plastic Quad Flat Package (PQFP) with
208
3.8
16.2
13.3
embedded heat spreader
11.9
C/W
Fine Pitch Ball Grid Array (FBGA)
256
3.8
26.9
22.8
21.5
C/W
484
3.2
20.5
17.0
15.9
C/W
676
3.2
16.4
13.0
12.0
C/W
896
2.4
13.6
10.4
9.4
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)
Array Voltage
VCC (V)
–40°C
Junction Temperature (°C)
0°C
25°C
70°C
1.425
0.87
0.92
0.95
1.00
1.500
0.83
0.88
0.90
0.95
1.575
0.80
0.85
0.87
0.92
85°C
1.02
0.97
0.93
100°C
1.04
0.98
0.95
Revision 13
2-5