National Instruments 653X user manual t t t t t

Chapter 3 Timing Diagrams
© National Instruments Corporation 3-3 653X User Manual
during, or after the REQ edge. If STARTRIG is asserted too close to the REQ edge, it may
not be recognized until the next REQ edge. To avoid this uncertainty, you can observe an
optional setup time of 15 ns, in other words, assert STARTRIG at least 15ns before the
start of the REQ pulse.
The STARTRIG signal is synchronized to the REQ edge using a flip-flop.
Because of this synchronization flip-flop, there is a one REQ-pulse delay
after STARTRIG before the data capture begins. There is a possibility of a
two-cycle delay if you do not observe the optional setup time mentioned in
the previous note.
Figure 3-2. External Request Timing Diagram
Parameter Description
tcCycle time
thw Width of low pulse
tpPropagation time to valid output data
tsu Setup time
thHold time
Data Valid
(Output Mode)
Data Valid
(Input Mode)
REQ
t
h
t
su
10 ns
Min
20 ns
Min
t
p
30 ns Max
t
hw
20 ns Min 20 ns Min
t
c
50 ns Min
t
w