Intel MCS48 User Manual page 371

8279/8279-5
A.C.
CHARACTERISTICS
T A
= 0°C
to 70°C,
V
ss
= OV,
(Note
1
)
Bus
Parameters
Read
Cycle:
Symbol
Parameter
8279
Min.
Max.
8279-5
Min. Max. Unit
*AR
Address
Stable Before
READ
50 ns
tRA
Address Hold Time
for
READ
5
ns
tRR
READ
Pulse
Width 420
250
ns
tRD
[21
Data Delay from
READ
300 150
ns
tAD^l Address
to
Data
Valid
450
250 ns
tDF
READ
to Data
Floating 10
100
10 100
ns
tRCY
Read
Cycle Time
1
1
Ms
Write Cycle:
Symbol
Parameter
8279
Min.
Max.
8279-5
Min. Max.
Unit
Uw
Address
Stable Before
WRITE
50
ns
%A
Address Hold Time
for
WRITE
20
ns
t
WW
WRITE
Pulse
Width
400
250
ns
tow Data
Set
Up Time
for
WR
ITE
300 150
ns
twD
Data Hold Time
for
WRITE
40
ns
*WCY
Write Cycle Time
1
1
MS
Notes:
1.
8279,
V CC
=
+5V
±5%;
8279-5,
V cc
= +5V
±10%.
2.
8279,
C
L
= 100pF;
8279-5,
C
L
=
150pF.
Other Timings:
Symbol
Parameter
8279
Min. Max.
8279-5
Min. Max.
Unit
*0W
Clock
Pulse
Width
230
120
nsec
tCY
Clock
Period
500 320
nsec
Keyboard
Scan Time:
5.1msec
Keyboard Debounce Time:
10.3
msec
Key
Scan Time:
80
jusec
Display Scan Time:
10.3
msec
Digit-on
Time:
Blanking Time:
Internal
Clock
Cycle:
480
Msec
1
60
Msec
1
Msec
Input
Waveforms
For
A.C. Tests
8-81
00742A