DS87C520_1 Datasheet, PDF (29/42 Pages) Dallas Semiconductor – EPROM/ROM High-Speed Micro

AC ELECTRICAL CHARACTERISTICS
PARAMETER
SYMBOL
33 MHz
MIN MAX
Oscillator Freq. (Ext. Osc.)
1/t_CLCL
0
33
(Ext. Crystal)
1
33
ALE Pulse Width
t_LHLL
40
Port 0 Address Valid to ALE
Low
t_AVLL
10
Address Hold after ALE Low
t_LLAX1
10
ALE Low to Valid Instruction In t_LLIV
56
ALE Low to PSEN Low
t_LLPL
10
PSEN Pulse Width
t_PLPH
55
PSEN Low to Valid Instr. In
t_PLIV
41
Input Instruction Hold after
PSEN
t_PXIX
0
Input Instruction Float after
t_PXIZ
26
PSEN
Port 0 Address to Valid Instr. In
t_AVIV
71
Port 2 Address to Valid Instr. In t_AVIV2
81
PSEN Low to Address Float
t_PLAZ
0
DS87C520/DS83C520
VARIABLE CLOCK
MIN
MAX
0
33
1
33
1.53t_CLCL-
5
0.5t_CLCL-5
UNITS
MHz
ns
ns
0.5t_CLCL-5
ns
2.5t_CLCL-20 ns
0.5t_CLCL-5
ns
2t_CLCL-5
ns
2t_CLCL-20
ns
0
ns
t_CLCL-5
ns
3t_CLCL-20
ns
3.5t_CLCL-25 ns
0
ns
NOTES FOR AC ELECTRICAL CHARACTERISTICS:
All parameters apply to both commercial and industrial temperature range operation unless otherwise
noted. All signals characterized with load capacitance of 80 pF except Port 0, ALE, PSEN , RD and WR
with 100 pF. Interfacing to memory devices with float times (turn off times) over 25 ns may cause
contention. This will not damage the parts, but will cause an increase in operating current. Specifications
assume a 50% duty cycle for the oscillator. Port 2 and ALE timing will change in relation to duty cycle
variation.
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