DS87C520-QNL Datasheet, PDF (32/43 Pages) Maxim Integrated Products – EPROM/ROM High-Speed Microcontrollers

DS87C520/DS83C520 EPROM/ROM High-Speed Microcontrollers
AC ELECTRICAL CHARACTERISTICS (Note 1)
PARAMETER
Oscillator
Frequency
External Oscillator
External Crystal
ALE Pulse Width
Port 0 Address Valid to ALE Low
Address Hold after ALE Low
ALE Low to Valid Instruction In
ALE Low to PSEN Low
PSEN Pulse Width
PSEN Low to Valid Instruction In
Input Instruction Hold after PSEN
Input Instruction Float after PSEN
Port 0 Address to Valid Instruction In
Port 2 Address to Valid Instruction In
PSEN Low to Address Float
SYMBOL
1/t_CLCL
t_LHLL
t_AVLL
t_LLAX1
t_LLIV
t_LLPL
t_PLPH
t_PLIV
t_PXIX
t_PXIZ
t_AVIV1
t_AVIV2
t_PLAZ
33 MHz
MIN MAX
0
33
1
33
40
10
(Note 2)
43
4
55
37
0
26
59
68
(Note 2)
VARIABLE CLOCK
MIN
0
MAX
33
1
33
1.5t_CLCL-5
0.5t_CLCL-5
(Note 2)
0.5t_CLCL-11
2t_CLCL-5
0
2.5t_CLCL-33
2t_CLCL-24
t_CLCL-5
3t_CLCL-32
3.5t_CLCL-38
(Note 2)
UNITS
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Note 1:
Note 2:
All parameters apply to both commercial and industrial temperature range operation unless otherwise noted.
Specifications to -40°C are guaranteed by design and are not production tested. AC electrical characteristics are not
100% tested, but are characterized and guaranteed by design. All signals characterized with load capacitance of 80pF
except Port 0, ALE, PSEN, RD, and WR with 100pF. Interfacing to memory devices with float times (turn off times)
over 25ns 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.
Address is driven strongly until ALE falls, and is then held in a weak latch until overdriven externally.
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