com20020-5 Standard Microsystems Corp., com20020-5 Datasheet - Page 47

• 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.

AD0-AD2,
D3-D7
nCS
ALE
nWR
FIGURE 11A - MULTIPLEXED BUS, 80XX-LIKE CONTROL SIGNALS; WRITE CYCLE
*
Note 1:
**
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 2:
t1
t2
t3
t4
t5
t6
t7
t8
Any cycle occurring after a write to Address Pointer Low Register requires a
next nWR.
Address Setup to ALE Low
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.
minimum of 4T from the trailing edge of nWR to the leading edge of the
Address Hold from ALE Low
nCS Setup to ALE Low
nCS Hold from ALE Low
ALE Low to nWR Low
Valid Data Setup to nWR High
Cycle Time (nWR Low to Next Time Low)**
Data Hold from nWR High
t1
t3
VALID
Parameter
t2,
t4
t5
47
VALID DATA
t6
min
4T*
30
10
30
10
10
20
15
t8
max
t7
Note 2
units
nS
nS
nS
nS
nS
nS
nS
nS
t8**