a54sx16p Actel Corporation, a54sx16p Datasheet - Page 23

• Manufacturer Part Number: a54sx16p
• Description: Sx Family Fpgas
• Manufacturer: Actel Corporation

Figure 1-11
from 1 MHz to 200 MHz.
Figure 1-11 • Power Dissipation
Junction Temperature (T
The temperature that you select in Designer Series
software is the junction temperature, not ambient
temperature. This is an important distinction because the
heat generated from dynamic power consumption is
usually hotter than the ambient temperature. Use the
equation below to calculate junction temperature.
Where:
T
ΔT = Temperature gradient between junction (silicon)
ΔT =
a
Junction Temperature = ΔT + T
= Ambient Temperature
θ
ja
and ambient
× P
Maximum Power Allowed
shows the characterized power dissipation numbers for the shift register design using frequencies ranging
1200
1000
800
600
400
200
0
0
a
=
20
J
)
Max. junction temp. (°C) – Max. ambient temp. (°C)
------------------------------------------------------------------------------------------------------------------------------------
40
60
EQ 1-13
80
θ
ja
Frequency MHz
(°C/W)
v3.2
100
P
θ
Package Thermal Characteristics
The device junction to case thermal characteristic is θ
and the junction to ambient air characteristic is θ
thermal characteristics for θ
different air flow rates.
The maximum junction temperature is 150 °C.
A sample calculation of the absolute maximum power
dissipation allowed for a TQFP 176-pin package at
commercial temperature and still air is as follows:
ja
120
= Power
= Junction to ambient of package.
Consumption section
located in the
section.
140
160
calculated
=
180
"Package Thermal Characteristics"
150°C – 70°C
-----------------------------------
28°C/W
200
from
ja
are shown with two
=
Estimating
2.86 W
SX Family FPGAs
θ
ja
numbers are
EQ 1-14
ja
Power
. The
1-19
jc
,