Datasheet

Rev. 0 | Page 38 of 44 | March 2006
ADSP-21261
ENVIRONMENTAL CONDITIONS
The ADSP-21261 processor is rated for performance over the
commercial temperature range, T
AMB
= 0°C to 70°C.
THERMAL CHARACTERISTICS
Table 32 and Table 33 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
Ψ
JT
= junction-to-top (of package) characterization parameter =
typical value from the tables below
P
D
= power dissipation. See EE Note No. EE-216
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.
Figure 33. Typical Output Delay or Hold vs. Load Capacitance
(at Ambient Temperature)
LOAD CAPACITANCE (pF)
7
012020 40 60 80 100
5
6
4
O
U
T
P
U
T
D
E
L
A
Y
O
R
H
O
L
D
(
n
s
)
3
–4
y = 0.0904x - 2.712
2
0
1
–1
–2
–3
T
J
T
CASE
Ψ
JT
PD×()+=
T
J
T
A
θ
JA
PD×()+=
Table 32. Thermal Characteristics for 136-Ball BGA
1
1
The thermal characteristics values provided in this table are modeled values.
Parameter Condition Typical Unit
θ
JA
Airflow = 0 m/s 31.0 °C/W
θ
JMA
Airflow = 1 m/s 27.3 °C/W
θ
JMA
Airflow = 2 m/s 26.0 °C/W
θ
JC
6.99 °C/W
Ψ
JT
Airflow = 0 m/s 0.16 °C/W
Ψ
JMT
Airflow = 1 m/s 0.30 °C/W
Ψ
JMT
Airflow = 2 m/s 0.35 °C/W
Table 33. Thermal Characteristics for 144-Lead LQFP
1
1
The thermal characteristics values provided in this table are modeled values.
Parameter Condition Typical Unit
θ
JA
Airflow = 0 m/s 32.5 °C/W
θ
JMA
Airflow = 1 m/s 28.9 °C/W
θ
JMA
Airflow = 2 m/s 27.8 °C/W
θ
JC
7.8 °C/W
Ψ
JT
Airflow = 0 m/s 0.5 °C/W
Ψ
JMT
Airflow = 1 m/s 0.8 °C/W
Ψ
JMT
Airflow = 2 m/s 1.0 °C/W