X24128
Guidelines for Calculating Typical Values of Bus
Pull-Up Resistors
SYMBOL TABLE
WAVEFORM
INPUTS
OUTPUTS
120
V
I
CC Max.
R
=
=1.8KΩ
Min.
Must be
steady
Will be
steady
100
80
OL Min.
t
R
R
=
MAX.
May change
from Low to
High
Will change
from Low to
High
C
BUS
Max.
60
40
20
0
Resistance
May change
from High to
Low
Will change
from High to
Low
Min.
Resistance
Don’t Care:
Changes
Allowed
Changing:
State Not
Known
20 40 60 80
0
100 120
N/A
Center Line
is High
Impedance
Bus Capacitance (pF)
Characteristics subject to change without notice. 13 of 16
REV 1.1 9/8/00
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