National Instruments AT E Series SCANCLK Signal

Chapter4 ConnectingSignals

ATE Series User Manual 4-40 ni.com

Eitherthe 20 MHz or 100 kHz internal timebase generates the SISOURCE

signalu nless you select some external source. Figure 4-23 shows the

timing requirements for the SISOURCE signal.

Figure4-23. SISOURCESignal Timing

SCANCLK Signal

SCANCLKis an output-only signal that generates a pulse with theleading

edgeoccurring approximately 50 to 100 ns after an A/D conversion begin s.

Thepolarity of this output is software selectable but is typically configured

so thata low-to-highleading edge can clock external AI multiplexers

indicating when the input signal has been sampled and can be removed.

This signal has a 400 to 500 ns pulse width and is software enabled.

Figure 4-24 shows the timing for the SCANCLK signal.

Note When using NI-DAQ,SCANCLK polarity is low-to-high and cannot be changed

programmatically.

Figure4-24. SCANCLKSignal Timing

tw=23 ns minimum

tp=50 ns minimum

tw=400 to 500 ns

td=50to100ns

CONVERT*

SCANCLK