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AM186 数据表(PDF) 62 Page - Advanced Micro Devices |
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AM186 数据表(HTML) 62 Page - Advanced Micro Devices |
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62 / 112 page ![]() 62 Am186TMER and Am188TMER Microcontrollers Data Sheet DRAF T 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 TC of 0 to 100 degrees Centigrade. TC is measured at the top center of the package. An increase in the ambient temperature causes a proportional increase in TC. The 50-MHz microcontroller is specified as 3.3 V, plus or minus 10%. Therefore, 3.6 V is used for calculating t y pical po w e r consu mpti on on t he 50- MH z microcontroller. Typical power supply current (ICC) in normal usage is 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 TC, the typical power consumption value from Table 11, and θ JC from Table 10, the junction temperature TJ can be calculated by using the following formula from Figure 17. TJ = TC + (P ⋅ θJC) Table 12 shows TJ values for the various versions of the 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). Table 12. Junction Temperature Calculation By using TJ from Table 12, the typical power consumption value from Table 11, and a θ JA value from Table 10, the typical ambient temperature TA can be calculated using the following formula from Figure 17. TA = TJ – (P ⋅ θJA) For example, TA for a 50-MHz PQFP design with a 2-layer board and 0 fpm airflow is calculated as follows: TA = 104.6 – (0.662 ⋅ 45) TA = 74.81 In this calculation, TJ comes from Table 12, P comes from Table 11, and θ JA comes from Table 10. See Table 13. TA for a 33-MHz TQFP design with a 4-layer to 6-layer board and 200 fpm airflow is calculated as follows: TA = 102.6 – (0.432 ⋅ 28) TA = 90.5 See Table 16 for the result of this calculation. Table 13 through Table 16 and Figure 18 through Fi g u r e 21 s h ow TA 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. P = MHz ⋅ I CC ⋅ Volts / 1000 Typical Power (P) in Watts MHz Typical ICC Volts 50 3.7 3.6 0.662 40 3.7 3.6 0.522 33 3.7 3.6 0.432 25 3.7 3.6 0.342 Speed/ Pkg/ Board TJ = TC + (P ⋅ θ JC) TJ TC P θ JC 50/P2 100 0.662 7 104.6 50/T2 100 0.662 10 106.6 50/P4–6 100 0.662 5 103.3 50/T4–6 100 0.662 6 104.0 40/P2 100 0.522 7 103.7 40/T2 100 0.522 10 105.2 40/P4–6 100 0.522 5 102.6 40/T4–6 100 0.522 6 103.1 33/P2 100 0.432 7 103.0 33/T2 100 0.432 10 104.3 33/P4–6 100 0.432 5 102.2 33/T4–6 100 0.432 6 102.6 25/P2 100 0.342 7 102.4 25/T2 100 0.342 10 103.4 25/P4–6 100 0.342 5 101.7 25/T4–6 100 0.342 6 102.1 |
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