DS87C520 Maxim, DS87C520 Datasheet - Page 32

• Manufacturer Part Number: DS87C520
• Description: The DS87C520/DS83C520 EPROM/ROM high-speed microcontrollers are fast 8051-compatible microcontrollers
• Manufacturer: Maxim

Note 1:
Note 2:
AC ELECTRICAL CHARACTERISTICS (Note 1)
Oscillator
Frequency
ALE Pulse Width
Port 0 Address Valid to ALE Low
Address Hold after ALE Low
ALE Low to Valid Instruction In
ALE Low to
Input Instruction Hold after
Input Instruction Float after
Port 0 Address to Valid Instruction In
Port 2 Address to Valid Instruction In
PSEN
PSEN
PSEN
Low to Address Float
Pulse Width
Low to Valid Instruction In
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.
PARAMETER
PSEN
External Oscillator
External Crystal
Low
PSEN
PSEN
SYMBOL
1/t
t
t
t
t
t
t
t
LLAX1
t
t
t
t
t
AVIV1
AVIV2
AVLL
LHLL
PLAZ
LLPL
PLPH
PXIX
LLIV
PLIV
PXIZ
CLCL
DS87C520/DS83C520 EPROM/ROM High-Speed Microcontrollers
32 of 43
(Note 2)
MIN
40
10
55
0
1
4
0
33 MHz
(Note 2)
MAX
33
33
43
37
26
59
68
0.5t
1.5t
0.5t
VARIABLE CLOCK
(Note 2)
2t
MIN
CLCL
CLCL
CLCL
CLCL
1
0
0
-5
-11
-5
-5
2.5t
3.5t
2t
3t
(Note 2)
t
MAX
CLCL
CLCL
CLCL
CLCL
CLCL
33
33
-24
-5
-32
-33
-38
UNITS
MHz
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns