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8255A18255A·5
A.C. CHARACTERISTICS
TA
=
O°C
to
70°C;
Vcc
=
+5V
±5%;
GND
=
OV
Bus Parameters
Read:
Write:
I
SYMBOL
PARAMETER
tAW
Address Stable Before
WR
ITE
twA
Address Stable
After
WR
ITE
tww
WRITE
Pulse
Width
tow
Data
Valid
to
WR
ITE
(T.E.)
two
Data
Valid
After
WR
ITE
Other
Timings:
SYMBOL
PARAMETER
tws
WR
= 1
to
Output
l1
]
tlR
Peripheral Data Before RD
tHR
Peripheral Data
After
RD
tAK
ACK
Pulse
Width
tST
STB
Pulse
Width
tps
Per.
Data Before
T.E.
of
STB
tpH
Per.
Data
After
T.E.
of
STB
tAO
ACK
= 0
to
Output
l1
]
tKO
ACK
= 1
to
Output
Float
twos
WR
= 1
to
OBF =
011]
tAOS
ACK
= 0
to
OBF
=
1111
tSIB
STB=OtoIBF=1[1]
tRIB
RD = 1
to
IBF = 0[1]
tRIT
RD =
Oto
INTR
= 0[1]
tSIT
STB
= 1
to
INTR
= 1[1]
tAIT
ACK
= 1
to
INTR
= 1[1]
tWIT
WR
=
Oto
INTR
= 0
11
]
I
MIN.
0
20
400
100
30
MIN.
0
0
300
500
0
180
20
Not,.:
1. Test Conditions: 8255A:
CL
=
loopF;8255A·5:
CL
= 150pF.
2.
Period of Reset pulse must be
at
leest
SOl'S
during or after power on.
Subsequent Reset pulse can be
500
ns min.
9-34
8255A
8255A
:~'
MAX.
UNIT
ns
•••
ns
"~,100;i:"'~~"
;:
ns
ns
""'
..
,
:.".
"J:~",
..
'
ns
~"i:.:J:,';:';;).:'\:;:,',:"':::.:,i'i·'
•...
.....
'~,'
.....
MAX.
.
MIN.
UNIT
350
....'
,"
ns
;'e)
i;'
.
...............
,
....
ns
f6>:'.
....
ns
Ft:r··
ns
"'
,"
ns
,c·
,
ns
..
.
ns
300
~.'
ns
250
'20-
25(}
ns
650
650
ns
350
350
ns
300
300
ns
300
300
ns
400
400
ns
300
.300
ns
350
....
3S0
.
ns
850
'
.......
ns
AFN-00744A-18