Datasheet

ADSP-21161N
Rev. C | Page 55 of 60 | January 2013
Capacitive Loading
Output delays and holds are based on standard capacitive loads:
30 pF on all pins (see Figure 36 on Page 54). Figure 38 shows
graphically how output delays and holds vary with load capaci-
tance. (Note that this graph or derating does not apply to output
disable delays; see Output Disable Time on Page 54.) The graphs
of Figure 38, Figure 39, and Figure 40 may not be linear outside
the ranges shown for Typical Output Delay vs. Load Capaci-
tance and Typical Output Rise Time (20% – 80%, V = Min) vs.
Load Capacitance.
ENVIRONMENTAL CONDITIONS
The thermal characteristics in which the DSP is operating influ-
ence performance.
Thermal Characteristics
The ADSP-21161N is packaged in a 225-ball chip scale package
ball grid array (CSP_BGA). The ADSP-21161N is specified for a
case temperature (T
CASE
). To ensure that the T
CASE
data sheet
specification is not exceeded, a heatsink and/or an air flow
source may be used. Use the center block of ground pins
(CSP_BGA balls: F6-10, G6-10, H6-10, J6-10, K6-10) to provide
thermal pathways to the printed circuit board’s ground plane. A
heatsink should be attached to the ground plane (as close as pos-
sible to the thermal pathways) with a thermal adhesive.
where:
• T
CASE
= Case temperature (measured on top surface
of package)
• T
AMB
= Ambient temperature °C
• PD = Power dissipation in W (this value depends upon the
specific application; a method for calculating PD is shown
under Power Dissipation).
•

CA
= Value from Table 39.
Figure 38. Typical Output Delay or Hold vs. Load Capacitance (at Max Case
Temperature)
Figure 39. Typical Output Rise/Fall Time (20% – 80%, V
DDEXT
= Max)
Figure 40. Typical Output Rise/Fall Time (20% – 80%, V
DDEXT
= Min)
LOAD CAPACITANCE – pF
25
–5
02103 0 60 90 120 150 180
20
15
10
5
NOMINAL
Y=0.0835X - 2.42
O
U
T
P
U
T
D
E
L
A
Y
O
R
H
O
L
D
–
n
s
LOAD CAPACITANCE – pF
16.0
8.0
0
0 20020 40 60 80 100 120 140 160 180
14.0
12.0
4.0
2.0
10.0
6.0
FALL TIME
RISETIME
Y = 0.0743X+1.5613
R
I
S
E
A
N
D
F
A
L
L
T
I
M
E
S
–
n
s
(
0
.
6
9
4
V
T
O
2
.
7
7
V
,
2
0
%
T
O
8
0
%
)
Y = 0.0414X + 2.0128
LOAD CAPACITANCE – pF
16.0
8.0
0
020020 40 60 80 100 120 140 160 180
14.0
12.0
4.0
2.0
10.0
6.0
FALL TIME
RISETIME
Y=0.0773X+1.4399
R
I
S
E
A
N
D
F
A
L
L
T
I
M
E
S
–
n
s
(
0
.
6
9
4
V
T
O
2
.
7
7
V
,
2
0
%
T
O
8
0
%
)
Y = 0.0417X + 1.8674
Table 39. Airflow Over Package Versus 
CA
Airflow (Linear Ft./Min.) 0 200 400

CA
(°C/W)
JC
1
1
= 6.8°C/W.
17.9 15.2 13.7
T
CASE
T
AMB
PD 
CA
+=