a2f500m3b-1csh484 Actel Corporation, a2f500m3b-1csh484 Datasheet - Page 21

• Manufacturer Part Number: a2f500m3b-1csh484
• Description: Actel
• Manufacturer: Actel Corporation

The 1.76 W power is less than the required 3.00 W. The design therefore requires a heat sink, or the
airflow where the device is mounted should be increased. The design's total junction-to-air thermal
resistance requirement can be estimated by
Determining the heat sink's thermal performance proceeds as follows:
where
A heat sink with a thermal resistance of 5.01°C/W or better should be used. Thermal resistance of heat
sinks is a function of airflow. The heat sink performance can be significantly improved with increased
airflow.
Carefully estimating thermal resistance is important in the long-term reliability of an Actel FPGA. Design
engineers should always correlate the power consumption of the device with the maximum allowable
power dissipation of the package selected for that device.
Note:
Temperature and Voltage Derating Factors
Table 2-7 • Temperature and Voltage Derating Factors for Timing Delays
θ
θ
Array
Voltage
VCC (V)
1.425
1.500
1.575
JA
SA
=
=
=
The junction-to-air and junction-to-board thermal resistances are based on JEDEC standard
(JESD-51) and assumptions made in building the model. It may not be realized in actual
application and therefore should be used with a degree of caution. Junction-to-case thermal
resistance assumes that all power is dissipated through the case.
0.37°C/W
Thermal resistance of the interface material between
the case and the heat sink, usually provided by the
thermal interface manufacturer
Thermal resistance of the heat sink in °C/W
(normalized to T
–40°C
0.81
0.78
0.86
θ
SA
θ
JA(total)
=
J
13.33°C/W 8.28°C/W
= 85°C, worst-case VCC = 1.425 V)
0.91
0.86
0.83
0°C
=
θ
θ
T
------------------ -
JA(TOTAL)
SA
J
–
P
=
T
–
A
EQ
R e v i s i o n 3
θ
Junction Temperature (°C)
JA(TOTAL)
=
7:
=
100°C 70°C
----------------------------------- -
25°C
0.93
0.88
0.85
θ
3.00 W
JC
–
+
–
–
0.37°C/W
θ
θ
CS
JC
Actel SmartFusion Intelligent Mixed Signal FPGAs
–
+
θ
θ
=
CS
SA
70°C
0.98
0.93
0.90
10.00°C/W
=
5.01°C/W
85°C
1.00
0.95
0.91
100°C
1.03
0.97
0.94
EQ 7
EQ 8
EQ 9
2 -9