Chapter 4
Connecting the Signals
4-36
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Figures 4-28 and 4-29 show the input and output timing requirements for
WFTRIG.
Figure 4-28.
WFTRIG Input Signal Timing
Figure 4-29.
WFTRIG Output Signal Timing
UPDATE* Signal
Any PFI pin can externally input the UPDATE* signal, which is available
as an output on the PFI5/UPDATE* pin.
As an input, UPDATE* is configured in the edge-detection mode. You can
select any PFI pin as the source for UPDATE* and configure the polarity
selection for either rising or falling edge. The selected edge of UPDATE*
updates the outputs of the DACs. To use UPDATE*, you must set the DACs
to posted-update mode.
As an output, UPDATE* reflects the actual update pulse connected to
the DACs, even if the updates are externally generated by another PFI.
The output is an active low pulse with a pulse width of 300 to 350 ns.
This output is set to high-impedance at startup.
Rising-Edge
Polarity
Falling-Edge
Polarity
t
w
= 10 ns minimum
t
w
t
w
= 50 to 100 ns
t
w