Data Sheet

Input
Output
t
MRT
= Minimum Time Between the End of the Second Input Pulse and the Beginning of the Retriggered Output
t
MRT
= 15 ns
t
MRT
t
MIR
t
RT
t
PLH
t
w
Input
Output
t
RT
= t
w
+ t
PLH
= (K × R
T
× C
T
) + t
PLH
Where:
t
MIR
= Minimum Input Retriggering Time
t
PLH
= Propagation Delay
t
RT
= Retrigger Time
t
w
= Output Pulse Duration Before Retriggering
SN54LV123A, SN74LV123A
www.ti.com SCLS393P –APRIL 1998–REVISED OCTOBER 2013
Retriggering Data
The minimum input retriggering time (t
MIR
) is the minimum time required after the initial signal before retriggering
the input. After t
MIR
, the device retriggers the output. Experimentally, it also can be shown that to retrigger the
output pulse, the two adjacent input signals should be t
MIR
apart, where t
MIR
= 0.30 × t
w
. The retrigger pulse
duration is calculated as shown in Figure 13.
Figure 13. Retrigger Pulse Duration
The minimum value from the end of the input pulse to the beginning of the retriggered output should be
approximately 15 ns to ensure a retriggered output (see Figure 14).
Figure 14. Input/Output Requirements
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