Datasheet

Rev. B | Page 56 of 68 | March 2013
ADSP-21483/ADSP-21486/ADSP-21487/ADSP-21488/ADSP-21489
THERMAL CHARACTERISTICS
The ADSP-2148x processor is rated for performance over the
temperature range specified in Operating Conditions on
Page 18.
Table 57 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 (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 57.
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.
Figure 45. Typical Output Rise/Fall Time
(20% to 80%, V
DD_EXT
= Min)
Figure 46. Typical Output Rise/Fall Delay
(V
DD_EXT
= Max)
LOAD CAPACITANCE (pF)
6
0
0
10
4
2
RISE AND FALL TIMES (ns)
25 20015050 75 100 125 175
y = 0.0571x + 0.5558
y = 0.0278x + 0.3138
y = 0.0258x + 0.3684
TYPE A DRIVE FALL
TYPE A DRIVE RISE
TYPE B DRIVE RISE
TYPE B DRIVE FALL
8
12
14
y = 0.0747x + 0.5154
LOAD CAPACITANCE (pF)
3
0
3.5
2
1
0.5
1.5
RISE AND FALL DELAY (ns)
2.5
y = 0.0152x + 1.7607
y = 0.0068x + 1.7614
y = 0.0196x + 1.2945
y = 0.0074x + 1.421
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
Figure 47. Typical Output Rise/Fall Delay
(V
DD_EXT
= Min)
LOAD CAPACITANCE (pF)
6
0
0
7
4
2
1
3
RISE AND FALL TIMES DELAY (ns)
125 20010025 17550 75 150
5
y = 0.0256x + 3.5859
y = 0.0116x + 3.5697
8
y = 0.0359x + 2.924
9
y = 0.0136x + 3.1135
TYPE A DRIVE FALL
TYPE A DRIVE RISE
TYPE B DRIVE FALL
TYPE B DRIVE RISE
T
J
T
CASE

JT
P
D
+=
T
J
T
A

JA
P
D
+=