Datasheet

Rev. D | Page 50 of 56 | April 2013
ADSP-21371/ADSP-21375
THERMAL CHARACTERISTICS
The processor is rated for performance over the temperature
range specified in Operating Conditions on Page 16.
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 standard JESD51-7 (LQFP_EP). The junction-to-case
measurement complies with MIL- STD-883. All measurements
use a 2S2P JEDEC test board.
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

JT
= junction-to-top (of package) characterization parameter
is the Typical value from Table 42.
P
D
= power dissipation
Values of 
JA
are provided for package comparison and PCB
design considerations. 
JA
can be used for a first order approxi-
mation of T
J
by the equation
where:
T
A
= ambient temperature C
Values of 
JC
are provided for package comparison and PCB
design considerations when an external heatsink is required.
Values of 
JB
are provided for package comparison and PCB
design considerations. Note that the thermal characteristics val-
ues provided in Table 42 are modeled values.
Figure 41. Typical Output Delay or Hold vs. Load Capacitance
(at Ambient Temperature)
LOAD CAPACITANCE (pF)
0 20050 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=0.0488X - 1.5923
T
J
T
CASE

JT
P
D
+=
T
J
T
A

JA
P
D
+=
Table 42. Thermal Characteristics for 208-Lead LQFP
E_PAD (With Exposed Pad Soldered to PCB)
Parameter Condition Typical Unit

JA
Airflow = 0 m/s 17.1 C/W

JMA
Airflow = 1 m/s 14.7 C/W

JMA
Airflow = 2 m/s 14.0 C/W

JC
9.6 C/W

JT
Airflow = 0 m/s 0.23 C/W

JMT
Airflow = 1 m/s 0.39 C/W

JMT
Airflow = 2 m/s 0.45 C/W

JB
Airflow = 0 m/s 11.5 C/W

JMB
Airflow = 1 m/s 11.2 C/W

JMB
Airflow = 2 m/s 11.0 C/W