THERMAL CHARACTERISTICS
TQFP Package
The variable P is power in watts. Typical power
supply current (ICC) for the Am186ER and Am188ER
microcontrollers is 3.7 mA per MHz of clock frequency.
The Am186ER and Am188ER microcontrollers are
specified for operation with case temperature ranges
from 0°C to +100°C for a commercial temperature
device. Case temperature is measured at the top
center of the package as shown in Figure 16. The
various temperatures and thermal resistances can be
determined using the equations in Figure 17 with
information given in Table 10.
θJA
θCA
TC
θJC
θJA is the sum of θJC and θCA . θJC is the internal
thermal resistance of the assembly. θCA is the case to
ambient thermal resistance.
θJA = θJC + θCA
Figure 16. 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 17. Thermal Characteristics Equations
Table 10. Thermal Characteristics (°C/Watt)
Airflow
(Linear Feet
per Minute)
θJC
θCA
θJA
Package/Board
0 fpm
7
7
38
32
28
26
46
36
30
28
18
16
14
12
24
22
20
18
45
39
35
33
56
46
40
38
23
21
19
17
30
28
26
24
200 fpm
400 fpm
600 fpm
0 fpm
PQFP/2-Layer
7
7
10
10
10
10
5
200 fpm
400 fpm
600 fpm
0 fpm
TQFP/2-Layer
200 fpm
400 fpm
600 fpm
0 fpm
5
PQFP/4-Layer
to 6-Layer
5
5
6
200 fpm
400 fpm
600 fpm
6
TQFP/4-Layer
to 6-Layer
6
6
Am186TMER and Am188TMER Microcontrollers Data Sheet
61
AMD [ AMD ]
