Datasheet

Rev. C | Page 66 of 76 | July 2013
ADSP-21477/ADSP-21478/ADSP-21479
THERMAL CHARACTERISTICS
The processor is rated for performance over the temperature
range specified in Operating Conditions on Page 21.
Table 58 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 (PBGA). The junction-to-case mea-
surement 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 58
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.
Note that the thermal characteristics values provided in
Table 58 are modeled values.
Figure 51. Typical Output Rise/Fall Time (20% to 80%,
V
DD_EXT
= Min)
Figure 52. Typical Output Delay or Hold vs. Load Capacitance
(at Ambient Temperature)
LOAD CAPACITANCE (pF)
6
0
0
10
4
2
RISE AND FALL TIMES (ns)
25 20015050 75 100 125 175
y = 0.0567x + 0.482
y = 0.0367x + 0.4502
y = 0.0314x + 0.5729
TYPE A DRIVE FALL
TYPE A DRIVE RISE
TYPE B DRIVE RISE
TYPE B DRIVE FALL
8
12
14
y = 0.0748x + 0.4601
LOAD CAPACITANCE (pF)
3
0
3.5
2
1
0.5
1.5
RISE AND FALL DELAY (ns)
2.5
y = 0.015x + 1.4889
y = 0.0088x + 1.6008
y = 0.0199x + 1.1083
y = 0.0102x + 1.2726
0 25 20015050 75 100 125 175
TYPE A DRIVE FALL
TYPE A DRIVE RISE
TYPE B DRIVE RISE
TYPE B DRIVE FALL
4
4.5
T
J
T
CASE

JT
P
D
+=
Table 57. Thermal Characteristics for 88-Lead LFCSP_VQ
Parameter Condition Typical Unit

JA
Airflow = 0 m/s 22.6 °C/W

JMA
Airflow = 1 m/s 18.2 °C/W

JMA
Airflow = 2 m/s 17.3 °C/W

JC
7.9 °C/W

JT
Airflow = 0 m/s 0.22 °C/W

JMT
Airflow = 1 m/s 0.36 °C/W

JMT
Airflow = 2 m/s 0.44 °C/W
Table 58. Thermal Characteristics for 100-Lead LQFP_EP
Parameter Condition Typical Unit
θ
JA
Airflow = 0 m/s 18.1 °C/W
θ
JMA
Airflow = 1 m/s 15.5 °C/W
θ
JMA
Airflow = 2 m/s 14.6 °C/W
θ
JC
2.4 °C/W
Ψ
JT
Airflow = 0 m/s 0.22 °C/W
Ψ
JMT
Airflow = 1 m/s 0.36 °C/W
Ψ
JMT
Airflow = 2 m/s 0.50 °C/W
Table 59. Thermal Characteristics for 196-Ball CSP_BGA
Parameter Condition Typical Unit
θ
JA
Airflow = 0 m/s 29.0 °C/W
θ
JMA
Airflow = 1 m/s 26.1 °C/W
θ
JMA
Airflow = 2 m/s 25.1 °C/W
θ
JC
8.8 °C/W
Ψ
JT
Airflow = 0 m/s 0.23 °C/W
Ψ
JMT
Airflow = 1 m/s 0.42 °C/W
Ψ
JMT
Airflow = 2 m/s 0.52 °C/W
T
J
T
A

JA
P
D
+=