adsp-2165ks-80 Analog Devices, Inc., adsp-2165ks-80 Datasheet - Page 20

• Manufacturer Part Number: adsp-2165ks-80
• Description: Dsp Microcomputers With Rom
• Manufacturer: Analog Devices, Inc.

SPECIFICATIONS
ADSP-2162/ADSP-2164/ADSP-2166
TEST CONDITIONS
Figure 18 shows voltage reference levels for ac measurements.
Figure 18. Voltage Reference Levels for AC Measurements
(Except Output Enable/Disable)
Output Disable Time
Output pins are considered to be disabled when they have
stopped driving and started a transition from the measured
output high or low voltage to a high impedance state. The out-
put disable time (t
as shown in Figure 19. The time t
when a reference signal reaches a high or low voltage level to
when the output voltages have changed by 0.5 V from the mea-
sured output high or low voltage.
The decay time, t
C
proximated by the following equation:
from which
is calculated. If multiple pins (such as the data bus) are disabled,
the measurement value is that of the last pin to stop driving.
ADSP-216x
L
, and the current load, i
OUTPUT
INPUT
DECAY
DIS
t
DIS
) is the difference of t
t
, is dependent on the capacitative load,
DECAY
= t
L
MEASURED
, on the output pin. It can be ap-
C
L
MEASURED
i
– t
0 5 .
L
DECAY
V
MEASURED
is the interval from
V
V
DD
2
DD
2
and t
DECAY
,
–20–
Output Enable Time
Output pins are considered to be enabled when they have made
a transition from a high-impedance state to when they start
driving. The output enable time (t
a reference signal reaches a high or low voltage level to when the
output has reached a specified high or low trip point, as shown
in Figure 19. If multiple pins (such as the data bus) are enabled,
the measurement value is that of the first pin to start driving.
REFERENCE
OUTPUT
(MEASURED)
(MEASURED)
SIGNAL
Measurements (Except Output Enable/Disable)
Figure 20. Equivalent Device Loading for AC
V
V
OUTPUT
OH
OL
OUTPUT STOPS
Figure 19. Output Enable/Disable
t
t
PIN
MEASURED
TO
DIS
DRIVING
50pF
V
V
HIGH-IMPEDANCE STATE. TEST CONDITIONS CAUSE
THIS VOLTAGE LEVEL TO BE APPROXIMATELY 1.5V.
OH
OL
t
DECAY
(MEASURED) +0.5V
(MEASURED) – 0.5V
ENA
I
I
OH
OL
) is the interval from when
OUTPUT STARTS
1.0V
2.0V
DRIVING
t
ENA
V
DD
2
V
(MEASURED)
V
(MEASURED)
OH
OL
REV. 0