Analog Devices TigerSHARC ADSP-TS201S, Specifications

Page: 37 / 48

ADSP-TS201S
Rev. C | Page 37 of 48 | December 2006
TEST CONDITIONS
The ac signal specifications (timing parameters) appear in
Table 29 on Page 28 . These include output disable time, output
enable time, and capacitive loading. The timing specifications
for the DSP apply for the voltage reference levels in
Figure 34 .
Output Disable Time
Output pins are considered to be disabled when they stop driv-
ing, go into a high impedance state, and start to decay from their
output high or low voltage. The time for the voltage on the bus
to decay by
Δ
V is dependent on the capacitive load, C
L
and the
load current, I
L
. This decay time can be approximated by the fol-
lowing equation:
The output disable time t
DIS
is the difference between
t
MEASURED_DIS
and t
DECAY
as shown in Figure 35 . The time
t
MEASURED_DIS
is the interval from when the reference signal
switches to when the output voltage decays
Δ
V from the mea-
sured output high or output low voltage. t
DECAY
is calculated
with test loads C
L
and I
L
, and with
Δ
V equal to 0.4 V.
Figure 31. Typical Drive Currents at Strength 5
Figure 32. Typical Drive Currents at Strength 6
Figure 33. Typical Drive Currents at Strength 7
OUTPUT PIN VOLTAGE (V)
0 2.8 0.4 0.8 1.2 1.6 2.0 2.4
O
U
T
P
U
T
P
IN
C
U
R
R
E
N
T
(m
A
)
–11
0
11
V
DD_IO
= 2.38V, +105°C
–22
–33
–44
–66
22
33
44
66
88
STRENGTH 5
V
DD_IO
= 2.5V, +25°C
V
DD_IO
= 2.63V, –40°C
I
OL
I
OH
V
DD_IO
= 2.38V, +105°C
V
DD_IO
= 2.5V, +25°C
V
DD_IO
= 2.63V, –40°C
77
55
–55
–88
–77
OUTPUT PIN VOLTAGE (V)
0 2.8 0.4 0.8 1.2 1.6 2.0 2.4
O
U
T
P
U
T
P
IN
C
U
R
R
E
N
T
(m
A
)
0
10
20
V
DD_IO
= 2.38V, +105°C
–10
–20
–30
–40
–100
30
40
50
60
100
STRENGTH 6
V
DD_IO
= 2.5V, +25°C
V
DD_IO
= 2.63V, –40°C
I
OL
I
OH
V
DD_IO
= 2.38V, +105°C
V
DD_IO
= 2.5V, +25°C
V
DD_IO
= 2.63V, –40°C
70
80
90
–50
–60
–70
–80
–90
OUTPUT PIN VOLTAGE (V)
0 2.8 0.4 0.8 1.2 1.6 2.0 2.4
O
U
T
P
U
T
P
IN
C
U
R
R
E
N
T
(m
A
)
–10
0
10
V
DD_IO
= 2.38V, +105°C
–20
–30
–40
–50
–110
20
30
40
50
110
STRENGTH 7
V
DD_IO
= 2.5V, +25°C
V
DD_IO
= 2.63V, –40°C
I
OL
I
OH
V
DD_IO
= 2.38V, +105°C
V
DD_IO
= 2.5V, +25°C
V
DD_IO
= 2.63V, –40°C
60
70
80
90
100
–60
–70
–80
–90
–100
Figure 34. Voltage Reference Levels for AC Measurements
(Except Output Enable/Disable)
Figure 35. Output Enable/Disable
INPUT
OR
OUTPUT
1.25V 1.25V
t
DECAY
C
L
V
Δ ( )
I
L
⁄
=
REFERENCE
SIGNAL
t
DIS
OUTPUT STARTS
DRIVING
V
OH (MEASURED)
–
⌬
V
V
OL (MEASURED)
+
⌬
V
t
MEASURED_DIS
V
OH (MEASURED)
V
OL (MEASURED)
1.65V
0.85V
HIGH IMPEDANCE STATE.
TEST CONDITIONS CAUSE THIS
VOLTAGE TO BE APPROXIMATELY 1.25V.
OUTPUT STOPS
DRIVING
t
DECAY
t
ENA
t
MEASURED_ENA
t
RAMP