SmartFusion Customizable System-on-Chip (cSoC)
Revision 10 2-7
Thermal Characteristics
Introduction
The temperature variable in the SoC Products Group Designer software refers to the junction
temperature, not the ambient, case, or board temperatures. This is an important distinction because
dynamic and static power consumption will cause the chip's junction temperature to be higher than the
ambient, case, or board temperatures. EQ 1 through EQ 3 give the relationship between thermal
resistance, temperature gradient, and power.
EQ 1
EQ 2
EQ 3
where
JA
= Junction-to-air thermal resistance
JB
= Junction-to-board thermal resistance
JC
= Junction-to-case thermal resistance
T
J
= Junction temperature
T
A
= Ambient temperature
T
B
= Board temperature (measured 1.0 mm away from the
package edge)
T
C
= Case temperature
P = Total power dissipated by the device
Table 2-6 • Package Thermal Resistance
Product
JA
JC
JB
UnitsStill Air 1.0 m/s 2.5 m/s
A2F200M3F-FG256 33.7 30.0 28.3 9.3 24.8 °C/W
A2F200M3F-FG484 21.8 18.2 16.7 7.7 16.8 °C/W
A2F200M3F-CS288 26.6 20.2 18.1 7.3 9.4 °C/W
A2F200M3F-PQG208I 38.5 34.6 33.1 0.7 31.6 °C/W
JA
T
J
A
–
P
------------------
=
JB
T
J
T
B
–
P
-------------------
=
JC
T
J
T
C
–
P
-------------------
=
