P R E L I M I N A R Y
THERMAL CHARACTERISTICS
TQFP Package
The variable P is power in watts. Power supply current
(ICC) is in mA per MHz of clock frequency.
The Am186ED microcontroller is specified for
operation with case temperature ranges from 0°C to
+100°C for a commercial device. Case temperature is
measured at the top center of the package as shown in
Figure 13. The various temperatures and thermal
resistances can be determined using the equations in
Figure 14 with information given in Table 11.
θJA
θCA
TC
θJC
The total thermal resistance is θJA; θJA is the sum of
θJC, the internal thermal resistance of the assembly,
and θCA, the case to ambient thermal resistance.
θJA = θJC + θCA
Figure 13. Thermal Resistance(°C/Watt)
θJA = θJC + θCA
P=ICC freq (MHz) VCC
TJ=TC+( P θJC
TJ=TA+ ( P θJA
)
)
TC=TJ–( P θJC
TC=TA+( P θCA
)
)
TA=TJ–( P θJA
)
TA=TC–( P θCA
)
Figure 14. Thermal Characteristics Equations
Table 11. Thermal Characteristics (°C/Watt)
Airflow
(Linear Feet
Package/Board
per Minute)
θJA
45
39
35
33
56
46
40
38
23
21
19
17
30
28
26
24
θJC
7
θCA
38
32
28
26
46
36
30
28
18
16
14
12
24
22
20
18
PQFP/2-Layer
0 fpm
200 fpm
400 fpm
600 fpm
0 fpm
7
7
7
TQFP/2-Layer
10
10
10
10
5
200 fpm
400 fpm
600 fpm
0 fpm
PQFP/4-Layer
to 6-Layer
200 fpm
400 fpm
600 fpm
0 fpm
5
5
5
TQFP/4-Layer
to 6-Layer
6
200 fpm
400 fpm
600 fpm
6
6
6
Am186ED/EDLV Microcontrollers
51
AMD [ AMD ]
