COM20020-5 Datasheet, PDF (49/58 Pages) SMSC Corporation – Universal Local Area Network Controller with 2K x 8 On-Board RAM

A0-A2
VALID
t1
t2
nCS
t3
t4
DIR
t5
t7
t6
nDS
D0-D7
t8
t9
VALID DATA
Parameter
t1 Address Setup to nDS Active
t2 Address Hold from nDS Inactive
t3 nCS Setup to nDS Active
t4 nCS Hold from nDS Inactive
t5 DIR Setup to nDS Active
t6 Cycle Time (nDS Low to Next Time Low)
t7 nDIR Hold from nDS Active
t8 nDS Low to Valid Data
t9 nDS High to Data High Impedence
min
15
10
5**
0
10
4T*
10
0
max units
nS
nS
nS
nS
nS
nS
nS
40
nS
20
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
** nCS may become active after control becomes active, but the access time will
now be 45nS measured from the leading edge of nCS.
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 12A - NON-MULTIPLEXED BUS, 68XX-LIKE CONTROL SIGNALS; READ
CYCLE
49