AM186ES Advanced Micro Devices, AM186ES Datasheet - Page 62

• Manufacturer Part Number: AM186ES
• Description: microcontrollers provide a low-cost/ high-performance solution for embedded system designers who wish to use the x86 architecture.
• Manufacturer: Advanced Micro Devices

Typical Ambient Temperatures
The typical ambient temperature specifications are
based on the following assumptions and calculations:
The commercial operating range of the Am186ER and
Am188ER microcontrollers is a case temperature T
0 to 100 degrees Centigrade. T
center of the package. An increase in the ambient
temperature causes a proportional increase in T
The 50-MHz microcontroller is specified as 3.3 V, plus
or minus 10%. Therefore, 3.6 V is used for calculating
t y p i c a l p o w e r c o n s u m p t i o n o n t h e 5 0 - M H z
microcontroller.
Typical power supply current (I
estimated at 3.7 mA per MHz of microcontroller clock
rate.
Typical power consumption can be calculated using the
following formula:
(Watts) = (3.7 mA/MHz) 50 MHz (3.6 V/1000)
Table 11 shows the variables that are used to calculate
the typical power consumption value for each version
of the Am186ER and Am188ER microcontrollers.
Table 11. Typical Power Consumption Calculation
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 following formulas from Figure 17 and the
variables in Table 10.
By using the maximum case rating T
power consumption value from Table 11, and
Table 10, the junction temperature T
by using the following formula from Figure 17.
T
Table 12 shows T
Am186ER and Am188ER microcontrollers. The
Speed/Pkg/Board column 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).
62
J
= T
MHz
50
40
33
25
C
+ (P
P = MHz I
JC
Typical I
)
J
values for the various versions of the
CC
3.7
3.7
3.7
3.7
Volts / 1000
CC
Am186
C
CC
is measured at the top
Volts
3.6
3.6
3.6
3.6
TM
) in normal usage is
J
ER and Am188
can be calculated
C
, the typical
Power (P)
in Watts
Typical
0.662
0.522
0.432
0.342
JC
C
.
from
C
TM
of
ER Microcontrollers Data Sheet
By using T
consumption value from Table 11, and a
Table 10, the typical ambient temperature T
calculated using the following formula from Figure 17.
T
For example, T
2-layer board and 0 fpm airflow is calculated as follows:
T
T
In this calculation, T
from Table 11, and
13.
T
board and 200 fpm airflow is calculated as follows:
T
T
See Table 16 for the result of this calculation.
Table 13 through Table 16 and Figure 18 through
F i g u r e 2 1 s h o w T
assumptions and calculations for a range of
with airflow from 0 linear feet per minute to 600 linear
feet per minute.
Speed/
Pkg/
Board
50/P2
50/T2
50/P4–6
50/T4–6
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
A
A
A
A
A
A
Table 12. Junction Temperature Calculation
= T
= 104.6 – (0.662 45)
= 74.81
for a 33-MHz TQFP design with a 4-layer to 6-layer
= 102.6 – (0.432 28)
= 90.5
J
– (P
J
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
from Table 12, the typical power
JA
T
A
C
)
for a 50-MHz PQFP design with a
T
J
JA
J
= T
A
comes from Table 12, P comes
comes from Table 10. See Table
C
b a s e d o n t h e p r e c e d i n g
0.662
0.662
0.662
0.662
0.522
0.522
0.522
0.522
0.432
0.432
0.432
0.432
0.342
0.342
0.342
0.342
+ (P
P
JC
)
10
10
10
10
7
5
6
7
5
6
7
5
6
7
5
6
JC
JA
value from
A
JA
104.6
106.6
103.3
104.0
103.7
105.2
102.6
103.1
103.0
104.3
102.2
102.6
102.4
103.4
101.7
102.1
can be
T
values
J