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R ea d O peration
DATA LINES
I/O DIRECTION
PCTL LINE
PFLG LINE
t1
100 s
As with the Write operation, the 3499A/B/C begins by testing PFLG for a
low state, indicating that the data is valid. When PFLG is low, the
3499A/B/C sets PCTL low and waits for PFLG to go high. The 3499A/B/C
will set PCTL high to indicate that it has completed the data read operation.
Data on the data bus must remain valid until after the 3499A/B/C sets
PCTL high.
DATA VALID
LATCHED
t2
t3
t4
45 s
50 s
40 s
35 s
Chapter 4 Features and Functions
Digital I/O Operation
t1 = T im e fro m ou tp u t
d isa b le to I/O lin e
h ig h (1 0 0 s m in im u m )
t2 = T im e fro m I/O lin e
h igh to ch eck for
P F L G lo w
(4 5 s m in im u m )
t3 = T im e fro m P F L G low
to ch eck fo r P C T L
lo w (5 0 s m in im u m )
t4 = T im e fro m P C T L low
to ch eck P F L G
h ig h (4 0 s m in im u m )
t5
t5 = T im e fro m P F L G
h ig h t o P C T L h igh
a n d d a ta la tch ed
(3 5 s m in im u m )
4
4
91
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