Triggering on Waveforms
3–70 TDS 684A, TDS 744A, & TDS 784A User Manual
Positive setup time always leads the clock edge; positive hold time always
follows the clocking edge. Setup time always leads the hold time by at least 2 ns
(TS + TH ≥ 2 ns). Attempting to set either time to reduce the 2 ns limit adjusts the
other time to maintain the limit.
Data (Ch1) transition occurs
within 10 ns after the clock
violating hold time limit.
The oscilloscope recognizes the
violation and triggers at the clock edge.
Cursors measure the setup/hold
violation zone which equals setup
time + hold time (30 ns).
Figure 3–42: Triggering on a Setup/Hold Time Violation
In most cases, you will enter positive values for both setup and hold time.
Positive values set the oscilloscope to trigger if the data source is still settling
inside the setup time before the clock or if it switches inside the hold time after
the clock. You can skew this “setup/hold violation zone” that the setup and hold
times form by entering negative values. See Figure 3–38 on page 3–63.
To Set Mode and Holdoff. Mode and holdoff can be set for all standard trigger
types and classes. To set mode and holdoff, refer to To Set Mode & Holdoff on
page 3–59. To learn more about trigger mode and holdoff, see the descriptions
Trigger Modes and Trigger Holdoff on page 3–51.
Triggering on Pulses
The TDS Oscilloscope can trigger on glitch or runt pulses, or it can trigger based
on the width or slew rate of a pulse. These capabilities makes the oscilloscope
suitable for such tasks as unattended monitoring for, and capturing of, a power
supply glitch or GO/NO GO slew rate testing of operational amplifiers. This