M1AFS600-PQ208 Datasheet, PDF (259/334 Pages) Microsemi Corporation – Fusion Family of Mixed Signal FPGAs

Fusion Family of Mixed Signal FPGAs
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 EQ 7:
_ja(total) = -^T---^J----_P^–-----T----^A- = -¹---⁰---⁰--₃--^°-_.-^C-₀---₀--–---_W-⁷----⁰---^°--^C--- = 10.00°C/W
Determining the heat sink's thermal performance proceeds as follows:
_JA(TOTAL) = _JC + _CS + _SA
EQ 7
where
EQ 8
_JA = 0.37°C/W
= Thermal resistance of the interface material between
the case and the heat sink, usually provided by the
thermal interface manufacturer
_SA = Thermal resistance of the heat sink in °C/W
_SA = _JA(TOTAL) – _JC – _CS
EQ 9
_SA = 13.33°C/W – 8.28°C/W – 0.37°C/W = 5.01°C/W
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 Microsemi 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: 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.
Temperature and Voltage Derating Factors
Table 3-7 • Temperature and Voltage Derating Factors for Timing Delays
(normalized to T_J = 70°C, Worst-Case VCC = 1.425 V)
Array Voltage
VCC (V)
–40°C
Junction Temperature (°C)
0°C
25°C
70°C
85°C
1.425
0.88
0.93
0.95
1.00
1.02
1.500
0.83
0.88
0.90
0.95
0.96
1.575
0.80
0.85
0.87
0.91
0.93
100°C
1.05
0.99
0.96
Revision 4
3-9