Intel MCS48 User Manual page 327

8255A/8255A-5
A.C.
CHARACTERISTICS
T A =
0°C
to
70°C;
V
Cc
= + 5V
±5%;
GND
=
OV
Bus Parameters
Read:
NOTE:
The
8255A-5 specifica-
tions
are not
final.
Some
parametric
limits
are sub-
ject
to
change.
PARAMETER
8255A
8255A-5
SYMBOL MIN.
MAX. MIN.
MAX. UNIT
*AR
Address
Stable
Before
R
EAD
ns
*RA
Address
Stable After
READ
ns
*RR
READ
Pulse
Width
300
300 ns
tRD
Data Valid
From
READ!
1
!
250
200
ns
tDF
Data
Float After
READ
10
150 10
100
ns
tRV
Time Between
READs
and/or
WR
ITEs
850
850 ns
Write:
PARAMETER
8255A 8255A-5
SYMBOL MIN.
MAX.
MIN.
MAX.
UNIT
*AW
Address Stable Before
WRITE
ns
*WA
Address Stable After
WR
ITE 20
20 ns
t
W W
WRITE
Pulse
Width
400 300 ns
*DW
Data Valid to
WR
ITE
(T.E.)
100
100
ns
*WD
Data Valid After
WRITE
30 30 ns
Other Timings:
PARAMETER
8255A 8255A-5
SYMBOL
MIN.
MAX.
MIN.
MAX. UNIT
t\/VB
WR
=
1
to
Output!
1] 350
350
ns
t|R
Peripheral
Data Before
RD
ns
*HR
Peripheral Data After
RD
ns
T-AK
ACK
Pulse
Width 300
300
ns
tST
STB
Pulse
Width 500 500
ns
tps
Per.
Data Before T.E. of
STB
ns
tPH Per.
Data After T.E. of
STB
180
180
ns
tAD
ACK
=
0toOutputl 1
l
300
300
ns
l KD
ACK
=
1
to
Output
Float
20 250 20
250
ns
tWOB
WR
=
1
toOBF =
0l
1
l
650 650
ns
*AOB
ACK
=
0toOBF = iHl
350
350
ns
tSiB
STB
=
to
IBF =
1H1
300 300
ns
tRIB
RD =
1
to
IBF
=
0l
1
]
300 300
ns
*RIT
RD
=
0to INTR =
0l 1
'
400 400
ns
tSIT
STB =
1
to
INTR =
1I 1
'
300
300
ns
UlT
ACK=
1
to
INTR
=
1I
1
1
350 350
ns
tWIT
WR
= 0to INTR =
0l 1
l
850 850
ns
Notes:
1.
Test Conditions:
8255A:
C|_
= 100pF; 8255A-5:
C|_
= 150pF.
2.
Period
of
Reset
pulse
must be
at
least
50/us during or after
power
on.
Subsequent
Reset pulse can be
500
ns min.
8-37
00744A