SMSC COM20020 manual NON-MULTIPLEXED BUS, 80XX-LIKE Control Signals Write Cycle

A0-A2

t1

nCS

t3

nWR

D0-D7

VALID

t2

t4

t5

	Note 2
t6	t5**
	t7
VALID DATA

	Parameter	min	max units
t1	Address Setup to nWR Active	15	nS
t2	Address Hold from nWR Inactive	10	nS
t3	nCS Setup to WR Active	5	nS
t4	nCS Hold from nWR Inactive	0	nS
t5	Cycle Time (nWR Low to Next Time Low)**	4T*	nS
t6	Valid Data Setup to nWR High	30**	nS
t7	Data Hold from nWR High	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

**nCS may become active after control becomes active, but the data setup time will now be 30 nS measured from the later of nCS falling or Valid Data available.

Note 1: The Microcontroller typically accesses the COM20020 on every other cycle. Therefore, the cycle time specified in the microcontroller's datasheet should be doubled when considering back-to-back COM20020 cycles.

Note 2: Any cycle occurring after a write to the Address Pointer Low Register requires a minimum of 4T from the trailing edge of nWR to the leading edge of the next nWR.

FIGURE 13 - NON-MULTIPLEXED BUS, 80XX-LIKE CONTROL SIGNALS; WRITE CYCLE

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