AM188ES-40KCW Datasheet, PDF (56/102 Pages) Advanced Micro Devices – High Performance, 80C186-/80C188-Compatible and 80L186-/80L188-Compatible, 16-Bit Embedded Microcontrollers

PRELIMINARY
Typical Ambient Temperatures
The typical ambient temperature specifications are
based on the following assumptions and calculations:
The commercial operating range of the Am186ES and
Am188ES microcontrollers is a case temperature T_C of
0 to 100 degrees Centigrade. T_C is measured at the top
center of the package. An increase in the ambient
temperature causes a proportional increase in T_C.
The 40-MHz microcontroller is specified as 5.0 V plus
or minus 5%. Therefore, 5.25 V is used for calculating
typical power consumption on the 40-MHz
microcontroller.
Microcontrollers up to 33 MHz are specified as 5.0 V
plus or minus 10%. Therefore, 5.5 V is used for
calculating typical power consumption up to 33 MHz.
Typical power supply current (I_CC) in normal usage is
estimated at 5.9 mA per MHz of microcontroller clock
rate.
Typical power consumption (watts) = (5.9 mA/MHz)
times microcontroller clock rate times voltage divided
by 1000.
Table 11 shows the variables that are used to calculate
the typical power consumption value for each version
of the Am186ES and Am188ES microcontrollers.
Table 11. Typical Power Consumption
Calculation
P = MHz ⋅ I_CC ⋅ Volts / 1000
MHz
Typical I_CC
Volts
40
5.9
5.25
33
5.9
5.5
25
5.9
5.5
20
5.9
5.5
Typical
Power (P) in
Watts
1.239
1.07085
0.81125
0.649
Thermal resistance is a measure of the ability of a
package to remove heat from a semiconductor device.
A safe operating range for the device can be calculated
using the formulas from Figure 14 and the variables in
Table 10.
By using the maximum case rating T_C, the typical
power consumption value from Table 11, and θ_JC from
Table 10, the junction temperature T_J can be
calculated by using the following formula from Figure
14.
T_J = T_C + (P ⋅ θ_JC)
Table 12 shows T_J values for the various versions of
the Am186ES and Am188ES microcontrollers. The
column titled Speed/Pkg/Board in Table 12 indicates
the clock speed in MHz, the type of package (P for
PQFP and T for TQFP), and the type of board (2 for 2-
layer and 4-6 for 4-layer to 6-layer).
Table 12. Junction Temperature Calculation
Speed/
Pkg/
Board
40/P2
40/T2
40/P4-6
40/T4-6
33/P2
33/T2
33/P4-6
33/T4-6
25/P2
25/T2
25/P4-6
25/T4-6
20/P2
20/T2
20/P4-6
20/T4-6
T_J
108.673
112.39
106.195
107.434
107.49595
110.7085
105.35425
106.4251
105.67875
108.1125
104.05625
104.8675
104.543
106.49
103.245
103.894
⋅ T_J = T_{C +} (P θ_JC)
T_C
P
θ_JC
100
1.239
7
100
1.239
10
100
1.239
5
100
1.239
6
100 1.07085
7
100 1.07085
10
100 1.07085
5
100 1.07085
6
100 0.81125
7
100 0.81125
10
100 0.81125
5
100 0.81125
6
100
0.649
7
100
0.649
10
100
0.649
5
100
0.649
6
By using T_J from Table 12, the typical power
consumption value from Table 11, and a θ_JA value from
Table 10, the typical ambient temperature T_A can be
calculated using the following formula from Figure 14:
T_A = T_J – (P ⋅ θ_JA)
For example, T_A for a 40-MHz PQFP design with a 2-
layer board and 0 fpm airflow is calculated as follows:
T_A = 108.673 – (1.239 ⋅ 45)
T_A = 52.918
In this calculation, T_J comes from Table 12, P comes
from Table 11, and θ_JA comes from Table 10. See Table
13.
T_A for a 33-MHz TQFP design with a 4-layer to 6-layer
board and 200 fpm airflow is calculated as follows:
T_A = 106.4251 – (1.07085 ⋅ 28)
T_A = 76.4413
See Table 16 for the result of this calculation.
Table 13 through Table 16 and Figure 15 through
Figure 18 show T_A based on the preceding
assumptions and calculations for a range of θ_JA values
with airflow from 0 linear feet per minute to 600 linear
feet per minute.
56
Am186/188ES and Am186/188ESLV Microcontrollers