ADSP-21060 Analog Devices, ADSP-21060 Datasheet - Page 40

• Manufacturer Part Number: ADSP-21060
• Description: ADSP-2106x SHARC DSP Microcomputer Family
• Manufacturer: Analog Devices

Example System Hold Time Calculation
To determine the data output hold time in a particular system,
first calculate t
to be the difference between the ADSP-2106x’s output voltage
and the input threshold for the device requiring the hold time. A
typical ∆V will be 0.4 V. C
data line), and I
data line). The hold time will be t
disable time (i.e., t
ADSP-21060/ADSP-21060L
REFERENCE
V
V
OH (MEASURED)
OL (MEASURED)
SIGNAL
t
DIS
OUTPUT STOPS
DECAY
L
DRIVING
is the total leakage or three-state current (per
DATRWH
using the equation given above. Choose ∆V
t
MEASURED
V
V
OH (MEASURED)
OL (MEASURED)
t
DECAY
L
for the write cycle).
is the total bus capacitance (per
HIGH-IMPEDANCE STATE.
TEST CONDITIONS CAUSE
THIS VOLTAGE TO BE
APPROXIMATELY 1.5V
DECAY
+ V
– V
OUTPUT STARTS
plus the minimum
t
ENA
1.0V
2.0V
DRIVING
V
V
OH (MEASURED)
OL (MEASURED)
Capacitive Loading
Output delays and holds are based on standard capacitive loads:
50 pF on all pins (see Figure 26). The delay and hold specifica-
tions given should be derated by a factor of 1.5 ns/50 pF for
loads other than the nominal value of 50 pF. Figures 29–30,
33–34 show how output rise time varies with capacitance. Fig-
ures 31, 35 show graphically how output delays and holds vary
with load capacitance. (Note that this graph or derating does
not apply to output disable delays; see the previous section
Output Disable Time under Test Conditions.) The graphs of
Figures 29, 30 and 31 may not be linear outside the ranges
shown.
OUTPUT
INPUT OR
PIN
OUTPUT
TO
50pF
1.5V
I
I
OH
OL
+1.5V
1.5V