ADSP-2111KG-66 Analog Devices, ADSP-2111KG-66 Datasheet - Page 24

• Manufacturer Part Number: ADSP-2111KG-66
• Description: ADSP-2100 Family DSP Microcomputers
• Manufacturer: Analog Devices

ADSP-21xx
SPECIFICATIONS (ADSP-2111)
TEST CONDITIONS
Figure 20 shows voltage reference levels for ac measurements.
Figure 20. 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
output disable time (t
t
interval from when a reference signal reaches a high or low
voltage level to when the output voltages have changed by 0.5 V
from the measured output high or low voltage.
DECAY
, as shown in Figure 21. The time t
OUTPUT
INPUT
DIS
) is the difference of t
V
V
OH
OL
(MEASURED)
(MEASURED)
REFERENCE
SIGNAL
Figure 22. Equivalent Device Loading for AC Measurements
(Except Output Enable/Disable)
OUTPUT
OUTPUT
MEASURED
t
DECAY
1.5V
PIN
2.0V
0.8V
3.0V
1.5V
0.0V
TO
OUTPUT STOPS
t
MEASURED
MEASURED
t
DIS
DRIVING
Figure 21. Output Enable/Disable
50pF
is the
V
V
and
OH
OL
(MEASURED) – 0.5V
(MEASURED) +0.5V
–24–
I
I
OL
OH
The decay time, t
C
approximated by the following equation:
from which
is calculated. If multiple pins (such as the data bus) are dis-
abled, the measurement value is that of the last pin to stop
driving.
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
when 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 21. If multiple pins (such as the data bus)
are enabled, the measurement value is that of the first pin to
start driving.
L
, and the current load, i
HIGH-IMPEDANCE STATE.
TEST CONDITIONS CAUSE
THIS VOLTAGE LEVEL TO BE
APPROXIMATELY 1.5V.
+1.5V
OUTPUT STARTS
1.0V
2.0V
DRIVING
t
DECAY
ENA
t
DIS
t
DECAY
, is dependent on the capacitative load,
= t
L
MEASURED
, on the output pin. It can be
V
V
OH
OL
C
L
(MEASURED)
(MEASURED)
E NA
i
– t
0.5 V
L
) is the interval from
DECAY
REV. B