ADSP-BF538_07 Datasheet, PDF (51/56 Pages) Analog Devices – Blackfin® Embedded Processor

135
130
125
FALL TIME
120
115
110
100
0
50
100
150
200
250
LOAD CAPACITANCE (pF)
Figure 50. Typical Output Fall Times (10% to 90%) vs. Load
Capacitance for Driver E at V_DDEXT = 2.7 V (MIN)
124
120
116
FALL TIME
112
108
104
100
0
50
100
150
200
250
LOAD CAPACITANCE (pF)
Figure 51. Typical Output Fall Times (10% to 90%) vs. Load
Capacitance for Driver E at V_DDEXT = 3.6 V (MAX)
THERMAL CHARACTERISTICS
To determine the junction temperature on the application
printed circuit board use:
T_J = T_CASE + (Ψ_JT × P_D)
where:
T_J = Junction temperature (؇C)
T_CASE = Case temperature (؇C) measured by customer at top
center of package.
Ψ_JT = From Table 35
P_D = Power dissipation (see Power Dissipation on Page 48 for
the method to calculate P_D)
ADSP-BF538/ADSP-BF538F
Values of θ_JA are provided for package comparison and printed
circuit board design considerations. θ_JA can be used for a first
order approximation of T_J by the equation:
T_J = T_A + (θ_JA × P_D)
where:
T_A = Ambient temperature (؇C)
Values of θ_JC are provided for package comparison and printed
circuit board design considerations when an external heatsink is
required.
Values of θ_JB are provided for package comparison and printed
circuit board design considerations.
In Table 35, airflow measurements comply with JEDEC stan-
dards 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 test board.
Table 35. Thermal Characteristics BC-316 Without Flash
Parameter
θ_JA
θ_JMA
θ_JMA
θ_JC
Ψ_JT
Ψ_JT
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
21.6
18.8
18.1
5.36
0.13
0.25
0.25
Unit
؇C/W
؇C/W
؇C/W
؇C/W
؇C/W
؇C/W
؇C/W
Table 36. Thermal Characteristics BC-316 With Flash
Parameter
θ_JA
θ_JMA
θ_JMA
θ_JC
Ψ_JT
Ψ_JT
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
20.9
18.1
17.4
5.01
0.12
0.24
0.24
Unit
؇C/W
؇C/W
؇C/W
؇C/W
؇C/W
؇C/W
؇C/W
Rev. 0 | Page 51 of 56 | May 2007