ADSP-BF549_15 Datasheet, PDF (93/102 Pages) Analog Devices – Blackfin Embedded Processor

ADSP-BF542/ADSP-BF544/ADSP-BF547/ADSP-BF548/ADSP-BF549
132
128
124
FALL TIME
120
116
112
108
0
50
100
150
200
250
LOAD CAPACITANCE (pF)
Figure 85. Typical Fall Time (10% to 90%) vs. Load Capacitance for
Driver E at V_DDEXT = 2.7 V
124
120
116
FALL TIME
112
108
104
100
0
50
100
150
200
250
LOAD CAPACITANCE (pF)
Figure 86. Typical Fall Time (10% to 90%) vs. Load Capacitance for
Driver E at V_DDEXT = 3.65 V
THERMAL CHARACTERISTICS
To determine the junction temperature on the application
printed circuit board use
TJ = TCASE + _JT  PD
where:
T_J =junction temperature (°C)
T_CASE = case temperature (°C) measured by customer at top cen-
ter of package.
_JT = from Table 64
P_D = power dissipation. (See Table 17 on Page 38 for a method
to calculate P_D.)
Values of _JA are provided for package comparison and printed
circuit board design considerations. _JA can be used for a first
order approximation of T_J by the equation
TJ = TA + _JA  PD
where:
T_A = ambient temperature (°C)
Table 64 lists values for _JC and _JB parameters. These values are
provided for package comparison and printed circuit board
design considerations. Airflow measurements in Table 64 com-
ply with JEDEC standards JESD51-2 and JESD51-6, and the
junction-to-board measurement complies with JESD51-8. The
junction-to-case measurement complies with MIL-STD-883
(Method 1012.1). All measurements use a 2S2P JEDEC
testboard.
Table 64. Thermal Characteristics, 400-Ball CSP_BGA
Parameter
θ_JA
θ_JB
θ_JC
ψ_JT
Condition
0 linear m/s air flow
1 linear m/s air flow
2 linear m/s air flow
0 linear m/s air flow
1 linear m/s air flow
2 linear m/s air flow
Typical
18.4
15.8
15.0
9.75
6.37
0.27
0.60
0.66
Unit
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
Rev. E | Page 93 of 102 | March 2014