Intel mcs-48 manual Bus Parameters !Note, Input Waveforms for AC Tests

8251A/S2657

A.C. CHARACTERISTICS

Bus Parameters !(Note 1)

Read Cycle:

SYMBOL	PARAMETER
tAR	Address Stable Before READ (CS, C/O)
tRA	Address Hold Time for READ (CS, C/O)
tRR	READ Pulse Width
tRD	Data Delay from READ
tDF	READ to Data Floating

MIN.	MAX.	UNIT	TEST CONDITIONS
50		ns	Note 2
50		ns	Note 2
250		ns
	250	ns	3, CL = 150 pF
10	100	ns

Write Cycle:

SYMBOL	PARAMETER	MIN.	MAX.	UNIT	TEST CONDITIONS
tAW	Address Stable Before WR ITE	50		ns
tWA	Address Hold Time for WR ITE	50		ns
tww	WRITE Pulse Width	250		ns
tow	Data Set Up Time for WRITE	150		ns
two	Data Hold Time for WRITE	50		ns
tRV	Recovery Time Between WRITES	6		tCY	Note 4

NOTES: 1. AC timings measured VOH = 2.0, VOL = 0.8, and with load circuit of Figure 1.

2.Chip Select (CS) and Command/Oata (C/O) are considered as Addresses.

3.Assumes that Address is valid before RD"

4.This recovery time is for Mode InitialiZ!'tion only. Write Data is allowed only when TxRDY = 1. Recovery Time between Writas for Asynchronous Mode is 8 tCY and for Synchronous Mode is 16 tCY'

Input Waveforms for AC Tests

X			:::x'-____
2 . 4 ----	~::	POINTS
0.45 _ ___oJ
		TEST

9-4 00216A