COM20020-5 Datasheet, PDF (44/58 Pages) SMSC Corporation – Universal Local Area Network Controller with 2K x 8 On-Board RAM

AD0-AD2,
D3-D7
nCS
ALE
nDS
DIR
VALID
t1
t2,
t4
t3
t6
t5
t9
VALID DATA
t7
t8
t10
Parameter
min
max units
t1 Address Setup to ALE Low
t2 Address Hold from ALE Low
t3 nCS Setup to ALE Low
t4 nCS Hold from ALE Low
t5 ALE Low to nDS Low
t6 nDS Low to Valid Data
t7 nDS High to Data High Impedance
t8 Cycle Time (nDS Low to Next Time Low)
t9 DIR Setup to nDS Active
t10 DIR Hold from nDS Inactive
30
nS
10
nS
10
nS
20
nS
15
nS
40
nS
0
20
nS
4T*
nS
10
nS
10
nS
* _{T is the Arbitration Clock Period.}
T is identical to XTAL1 if SLOW ARB = 0,
T is twice XTAL1 period if SLOW ARB = 1
Note 1: The Microcontroller typically accesses the COM20020-5 on every other cycle.
Therefore, the cycle time specified in the microcontroller's datasheet
should be doubled when considering back-to-back COM20020-5 cycles.
FIGURE 10 - MULTIPLEXED BUS, 68XX-LIKE CONTROL SIGNALS; READ CYCLE
44