Datasheet

Table 42 airflow measurements comply with JEDEC standards
JESD51-2 and JESD51-6 and the junction-to-board measure-
ment complies with JESD51-8. Test board design complies with
JEDEC standards JESD51-7 (MQFP). The junction-to-case
measurement complies with MIL- STD-883. All measurements
use a 2S2P JEDEC test board.
The ADSP-21371 processor is rated for performance over the
temperature range specified in Operating Conditions on
Page 15.
O
O
O
U
U
T
T
P
D
D
E
L
L
A
Y
R
H
(
n
s
)
THERMAL CHARACTERISTICS
To determine the junction temperature of the device while on
the application PCB, use:
where:
T
J
= junction temperature °C
T
CASE
= 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 Table 42.
P
D
= power dissipation
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 heatsink is required.
ADSP-21371
Values of θ
JB
are provided for package comparison and PCB
design considerations. Note that the thermal characteristics val-
10
0 20050 100 150
Y = 0.0488X - 1.5923
ues provided in Table 42 are modeled values.
8
Table 42. Thermal Characteristics for 208-Lead MQFP
6
4
2
0
-2
-4
Parameter Condition Typical Unit
θ
JA
Airflow = 0 m/s 30.82 °C/W
θ
JMA
Airflow = 1 m/s 27.53 °C/W
θ
JMA
Airflow = 2 m/s 26.22 °C/W
θ
JC
14.04 °C/W
Ψ
JT
Airflow = 0 m/s 2.0 °C/W
Ψ
JMT
Airflow = 1 m/s 2.65 °C/W
Ψ
JMT
Airflow = 2 m/s 3.12 °C/W
LOAD CAPACITANCE (pF)
Figure 39. Typical Output Delay or Hold vs. Load Capacitance
(at Ambient Temperature)
T
J
= T
CASE
+ ( Ψ
JT
× P
D
)
T
J
= T
A
+ ( θ
JA
× P
D
)
Rev. 0 | Page 45 of 48 | June 2007