
DS2250(T)
11 of 20
AC CHARACTERISTICS: EXPANDED
BUS MODE TIMING SPECIFICATIONS                  
(t
A
=0
°
C to70
°
C; V
CC
=5V 
±
 5%)
#
PARAMETER
1
Oscillator Frequency
2
ALE Pulse Width
3
Address Valid to ALE Low
4
Address Hold After ALE Low
5
ALE Low to Valid Instr. In
@ 12 MHz
@ 16 MHz
6
ALE Low to 
PSEN
  Low
7
PSEN
  Pulse Width
8
PSEN
  Low to Valid Instr. In
@ 12 MHz
@ 16 MHz
9
Input Instr. Hold after 
PSEN
  Going High
10
Input Instr. Float after 
PSEN
  Going High
11
Address Hold after 
PSEN
  Going High
12
Address Valid to Valid Instr. In @ 12 MHz
@ 16 MHz
13
PSEN
  Low to Address Float
14
RD
 Pulse Width
15
WR
  Pulse Width
16
RD
 Low to Valid Data In
@ 12 MHz
@ 16 MHz
17
Data Hold after 
RD
 High
18
Data Float after 
RD
 High
19
ALE Low to Valid Data In
@ 12 MHz
@ 16 MHz
20
Valid Addr. to Valid Data In
@ 12 MHz
@ 16 MHz
21
ALE Low to 
RD
 or 
WR
  Low
22
Address Valid to 
RD
 or 
WR
  Low
23
Data Valid to 
WR
  Going Low
24
Data Valid to 
WR
  High
@ 12 MHz
@ 16 MHz
25
Data Valid after 
WR
  High
26
RD
 Low to Address Float
27
RD
 or 
WR
  High to ALE High
SYMBOL
1/t
CLK
t
ALPW
t
AVALL
t
AVAAV
t
ALLVI
MIN
1.0
2t
CLK
 -40
t
CLK
 -40
t
CLK
 -35
MAX
16 (-16)
UNITS
MHz
ns
ns
ns
ns
4t
CLK
 -150
4t
CLK
 -90
t
ALLPSL
t
PSPW
t
PSLVI
t
CLK
 -25
3t
CLK
 -35
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
3t
CLK
 -150
3t
CLK
 -90
t
PSIV
t
PSIX
t
PSAV
t
AVVI
0
t
CLK
 -20
t
CLK
 -8
5t
CLK
 -150
5t
CLK
 -90
t
PSLAZ
t
RDPW
t
WRPW
t
RDLDV
0
6t
CLK
 -100
6t
CLK
 -100
5t
CLK
 -165
5t
CLK
 -105
t
RDHDV
t
RDHDZ
t
ALLVD
0
2t
CLK
 -70
8
CLK
 -150
8t
CLK
 -90
9t
CLK
 -165
9t
CLK
 -105
3t
CLK
 +50
t
AVDV
t
ALLRDL
t
AVRDL
t
DVWRL
t
DVWRH
3t
CLK
 -50
4t
CLK
 -130
t
CLK
 -60
7t
CLK
 -150
7t
CLK
 -90
t
CLK
 -50
t
WRHDV
t
RDLAZ
t
RDHALH
0
t
CLK
 -40
t
CLK
 +50