com20020-5 Standard Microsystems Corp., com20020-5 Datasheet - Page 49

• Manufacturer Part Number: com20020-5
• Description: Com20020-5 Ulanc Universal Local Area Network Controller With 2k X 8 On-board Ram
• Manufacturer: Standard Microsystems Corp.

A0-A2
DIR
nDS
D0-D7
nCS
FIGURE 12A - NON-MULTIPLEXED BUS, 68XX-LIKE CONTROL SIGNALS; READ
*
**
Note 1:
now be 45nS measured from the leading edge of nCS.
nCS may become active after control becomes active, but the access time will
t1
t3
t4
t6
T is the Arbitration Clock Period.
T is identical to XTAL1 if SLOW ARB = 0,
T is twice XTAL1 period if SLOW ARB = 1
t2
t5
t7
t8
t9
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.
Address Setup to nDS Active
nCS Setup to nDS Active
Address Hold from nDS Inactive
nCS Hold from nDS Inactive
DIR Setup to nDS Active
Cycle Time (nDS Low to Next Time Low)
nDIR Hold from nDS Active
nDS Low to Valid Data
nDS High to Data High Impedence
t1
t5
t3
Parameter
t8
CYCLE
49
VALID
t6
VALID DATA
min
15
10
10
4T*
10
0
5**
0
max
40
20
t9
t7
t2
t4
units
nS
nS
nS
nS
nS
nS
nS
nS
nS