Datasheet

Rev. G | Page 38 of 48 | December 2012
ADSP-21261/ADSP-21262/ADSP-21266
ENVIRONMENTAL CONDITIONS
The ADSP-2126x processor is rated for performance under T
AMB
environmental conditions specified in the Operating Condi-
tions on Page 14.
THERMAL CHARACTERISTICS
Table 38 and Table 39 airflow measurements comply 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. All measure-
ments 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 38 and Table 39 (
JMT
indicates
moving air).
P
D
= power dissipation. See Estimating Power Dissipation for
ADSP-21262 SHARC DSPs (EE-216) for more information.
Values of 
JA
are provided for package comparison and PCB
design considerations (
JMA
indicates moving air). 
JA
can be
used for a first order approximation 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 heat sink is required.
Figure 33. Typical Output Delay or Hold vs. Load Capacitance
(at Ambient Temperature)
LOAD CAPACITANCE (pF)
020050 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
+=
Table 38. Thermal Characteristics for 136-Ball BGA
Parameter Condition Typical Unit

JA
Airflow = 0 m/s 31.0 C/W

JMA
Airflow = 1 m/s 27.3 °C/W

JMA
Airflow = 2 m/s 26.0 °C/W

JC
6.99 °C/W

JT
Airflow = 0 m/s 0.16 °C/W

JMT
Airflow = 1 m/s 0.30 °C/W

JMT
Airflow = 2 m/s 0.35 °C/W
Table 39. Thermal Characteristics for 144-Lead LQFP
Parameter Condition Typical Unit

JA
Airflow = 0 m/s 32.5 °C/W

JMA
Airflow = 1 m/s 28.9 °C/W

JMA
Airflow = 2 m/s 27.8 °C/W

JC
7.8 °C/W

JT
Airflow = 0 m/s 0.5 °C/W

JMT
Airflow = 1 m/s 0.8 °C/W

JMT
Airflow = 2 m/s 1.0 °C/W
T
J
T
A

JA
P
D
+=