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Rev. D
|
Page 48 of 56
|
November 2008
ADSP-21367/ADSP-21368/ADSP-21369
THERMAL CHARACTERISTICS
The ADSP-21367/ADSP-21368/ADSP-21369 processors are
rated for performance over the temperature range specified in
Operating Conditions on Page 16
.
and
airflow measurements comply with
JEDEC standards JESD51-2 and JESD51-6 and the junction-to-
board measurement complies with JESD51-8. Test board design
complies with JEDEC standards JESD51-9 (BGA_ED) and
JESD51-8 (LQFP_EP). The junction-to-case measurement com-
plies with MIL-STD-883. All measurements use a 2S2P JEDEC
test board.
The LQFP-EP package requires thermal trace squares and ther-
mal vias, to an embedded ground plane, in the PCB. Refer to
JEDEC standard JESD51-5 for more information.
To determine the junction temperature of the device while on
the application PCB, use:
where:
T
J
= junction temperature (
°
C)
T
TOP
= case temperature (
°
C) measured at the top center of the
package
Ψ
JT
= junction-to-top (of package) characterization parameter is
the typical value from
and
P
D
= power dissipation (see EE Note EE-299)
Values of
θ
JA
are provided for package comparison and PCB
design considerations.
θ
JA
can be used for a first-order approxi-
mation of T
J
by the equation:
where:
T
A
= ambient temperature (
°
C)
Values of
θ
JC
are provided for package comparison and PCB
design considerations when an external heat sink is required.
This is only applicable when a heat sink is used.
Values of
θ
JB
are provided for package comparison and PCB
design considerations. The thermal characteristics values pro-
vided in
and
are modeled values @ 2 W.
Figure 45. Typical Output Delay or Hold vs. Load Capacitance
(at Junction Temperature)
Figure 46. SDCLK Typical Output Delay or Hold vs. Load Capacitance
(at Junction Temperature)
LOAD CAPACITANCE (pF)
0
200
50
100
150
10
8
O
U
T
P
U
T
D
E
L
A
Y
O
R
H
O
L
D
(n
s
)
-
4
6
0
4
2
-
2
y = 0.04
88
x - 1.592
3
LOAD CAPACITANCE (pF)
6
-
2
0
100
2
0
8
4
R
I
S
E
A
N
D
F
A
L
L
T
IM
E
S
(n
s
)
200
150
50
y = 0.0256x
-
0.021
Table 44. Thermal Characteristics for 256-Ball BGA_ED
Parameter
Condition
Typical
Unit
θ
JA
Airflow = 0 m/s
12.5
°
C/W
θ
JMA
Airflow = 1 m/s
10.6
°
C/W
θ
JMA
Airflow = 2 m/s
9.9
°
C/W
θ
JC
0.7
°
C/W
θ
JB
5.3
°
C/W
Ψ
JT
Airflow = 0 m/s
0.3
°
C/W
Ψ
JMT
Airflow = 1 m/s
0.3
°
C/W
Ψ
JMT
Airflow = 2 m/s
0.3
°
C/W
Table 45. Thermal Characteristics for 208-Lead LQFP EPAD
(With Exposed Pad Soldered to PCB)
Parameter
Condition
Typical
Unit
θ
JA
Airflow = 0 m/s
17.1
°
C/W
θ
JMA
Airflow = 1 m/s
14.7
°
C/W
θ
JMA
Airflow = 2 m/s
14.0
°
C/W
θ
JC
9.6
°
C/W
Ψ
JT
Airflow = 0 m/s
0.23
°
C/W
Ψ
JMT
Airflow = 1 m/s
0.39
°
C/W
Ψ
JMT
Airflow = 2 m/s
0.45
°
C/W
Ψ
JB
Airflow = 0 m/s
11.5
°
C/W
Ψ
JMB
Airflow = 1 m/s
11.2
°
C/W
Ψ
JMB
Airflow = 2 m/s
11.0
°
C/W
T
J
T
TOP
Ψ
JT
P
D
×
(
)
+
=
T
J
T
A
θ
JA
P
D
×
(
)
+
=